RAMSES User's Guide
Contents
1. Character Directory where IC files are stored See section ILES LEN 80 array 4 1 for details 15 3 4 Output parameters This namelist block called OUTPUT_PARAMS is used to set up the frequency and properties of data output to disk Variable name syntax and default value Fortran type Description tend 0 Real Final time of the simulation delta_tout 0 Real Time increment between outputs aend 0 Real Final expansion factor of the simulation delta_tout 0 Real Expansion factor increment between outputs Number of specified output time If tend or aend is not used at least one output time ES G should be given corresponding to the end of the simulation tout 0 0 0 0 0 0 Real array Value of specified output time Value of specified output expansion factor aout 1 1 1 1 1 1 Real array for cosmology runs only aout 1 0 means present epoch or zero redshift Frequency of additional outputs in units of coarse time steps foutput 1 means one out foutput 1000000 Integer put at each time step Specified outputs see above will not be superceded by this parame ter 16 3 5 Boundary conditions This namelist block called BOUNDARY_PARAMS is used to set up boundary conditions on the current simulation If this namelist block is absent periodic boundary conditions are assumed Setting up other types of boundary conditions in RAMSES is quite complex The reader is invited to read the co2. 4 5 Post processing utilities Several post processing codes are available in the current package in directory utils f90 These are very simple pieces of software performing rather basic operations on RAMSES generated outputs Users are encouraged to edit and modify these routines in order to design specific post processing applications We briefly describe them now e amr2map this application reads RAMSES outputs and generates a projected map along one principal axis The output is a binary Fortran image that can be read using any image processing tool e amr2cube this application reads RAMSES outputs and generates a 3D Cartesian cube with only one flow variable represented The output is a binary Fortran file raw data or grafic data or a VTK file that can be read using any data visualization tool e part2map this application reads RAMSES outputs for collisionless particles only and projected the particle distribution along one principal axis The output is a binary Fortran image e part2cube this application reads RAMSES outputs for particles only and generates a CIC interpolated density field The output is a binary Fortran file Each one of these codes is a stand alone application that can be compiled straightforwardly by typing directly for example 90 amr2map f90 o amr2map In directory utils idl you can find a set of IDL routines to be used in order to display AMR data using IDL see http www ittvis com Here is an
3. RAMSES User s Guide Self gravitating fluid dynamics with Adaptive Mesh Refinement using massively parallel computers Irfu E Romain Teyssier saclay Version Issue Version 3 0 Last Update November 6 2008 Contents 1 Introduction Ll About This aides 25 4 424 6 6 4 RoRO Rex Poa eee eh eRe ES L2 Wetting RAMSES noo 44624 448444 284 oh B44 RES EES EAR SS L3 rn fe Ka he a ee Ae EA eR we ek Ee RO 14 Acknowledgements 6 22 65 s o o RR a L5 The DeCILL License 20202002 koe 033m sc eomm ose Boxe Ae a wel 2 Getting started 2 1 Obtaining the package 2 22292 ct eo e Romo OE oe Ro non 2 2 Compiling thecod 2 458 444454646 m e kk RR Ros a e Ro dos 2 3 Executing the test case me sa adaos E e p ls 24 Reading the Log Eijle 2 22222 n hee eee omo RR dms 3 Runtime Parameters 3 1 Global 4 0 1299 asa pae wa Aa ORR ee we a 2 2 AMP 6 how baa Rk eG eh Res Gee d ed vede Poe dox EE GS 3 3 Initial conditions lt 6 24 kooco9 woe ded we ee ee ee LUE e did 34 Output parameters so sa ne caw bbe yo ee Rok WR X ee ee ee 45 Boundary conditions o sas c Taaa suoraa aa 88d ae OR E SOR UR ee a 36 Piydrodynami ssolWwer 04244 ko ok uos RA WDR RR E RC e EDAD UR UR R s a Physical parameters so c omo oh dba A RO ROLE Ee RR EUR s eS Oo Poon SONE cs eoo rl em Re Dum Rex c OR uu A a Ro EUR RE a 39 Rebnemnent strategy oo 224 E o RT A a eo Be EUER IE RSS 4 Cosmological simulations 4 1 Parameter file and
4. ibound_max 0 jbound_max 0 Integer arrays kbound_max 0 Likewise for the upper right and upper corner of each boundary region 17 3 6 Hydrodynamics solver This namelist is called amp HYDRO PARAMS and is used to specify runtime parameters for the Go dunov solver These parameters are quite standard in computational fluid dynamics We briefly describe them now Variable name syntax Fortran type Description and default value yP E gamma 1 4 Real Adiabatic exponent for the perfect gas EOS courant_factor 0 5 Real CFL number for time step control less than 1 A Real Minimum density to prevent floating excep tions ER Real Minimum sound speed to prevent floating ex ceptions Name of the desired Riemann solver Possi Character ble choices are exact acoustic 11 riemann llf LEN 20 hll or hllc for the hydro solver and M Llf h11 roe hlld upwind and hydro for the MHD solver Name of the desired 2D Riemann solver for Character the induction equation MHD only Possi i 2d 11f rap LEN 20 ble choices are upwind llf roe h11 and hlld Maximum number of iterations used in the ex niter riemann 10 Integer act Riemann solver Type of slope limiter used in the Godunov scheme for the piecewise linear reconstruction slope_type 0 First order scheme slope_type 1 MinMod limiter 1 type 2 M en limiter paid Iiac slope_type onCen limit
5. 4 4 Level 4 has 8 grids 8 8 8 Level 5 has 16 grids 16 16 16 Level 6 has 28 grids 28 28 28 Level 7 has 37 grids 37 37 37 Level 8 has 18 grids 18 18 18 Level 9 has 15 grids 15 15 15 Level 10 has 13 grids 13 13 13 Main step 43 mcons 0 00E 00 econs 8 07E 17 epot 0 00E 00 ekin 1 38E 00 Fine step 688 t 2 45001E 01 dt 3 561E 04 a 1 000E 00 mem 7 8 Run completed To save the standard output in a file the user is encouraged to redirect the standard output in a Log File in which all control variables are outputted and stored as well as simulation data for 1D cases only bin ramsesid namelist tubeid nml gt tubeid log To monitor the progress of longer runs you can also redirect standard output to both a log file and the terminal at the same time with bin ramsesid namelist tubeid nml tee tubeld log 86 87 88 89 90 2 4 Reading the Log File We will now briefly describe the structure and the nature of the information available in the Log Files We will use as example the file tube1d log which should contain starting from the top al ah af Illl elfe el at 3f af p e sh ah uut E zi E Lb liek A if dee qu hal AER B E of e al QU uf Zr ST EA Tael ZL _ E E T SENS T MN Mae lll Version 3 0 written by Romain Teyssier CEA DSM DAPNIA SAP c CEA 1999 2007 Working with nproc 1 for ndim 1 Bu
6. 13 3 2 AMR grid This set of parameters called AMR_PARAMS controls the AMR grid global properties Param eters specifying the refinement strategy are described in the amp REFINE PARAMS block which is used only if levelmax gt levelmin Variable name syntax Fortran type Description and default value yP p Minimum level of refinement This parameter levelmin 1 Integer sets the size of the coarse or base grid by n gievelmin Maximum level of refinement If levelmax 1 Integer levelmax levelmin this corresponds to a standard cartesian grid Maximum number of grids or octs that can ngridmax 0 Integer be allocated during the run within each MPI process Maximum number of grids or octs that can be ngridtot 0 Integer allocated during the run for all MPI processes One has in this case ngridmax ngridtot ncpu Maximum number of particles that can be allo Pepe Integer cated during the run within each MPI process Maximum number of particles that can be PEETER Interer allocated during the run for all MPI pro P 8 cesses Obviously one has in this case npartmax nparttot ncpu nexpand 1 Integer Number of mesh expansions mesh smoothing boxlen 1 0 Real Box size in user units 14 3 3 Initial conditions This namelist block called amp INIT PARAMS is used to set up the initial conditions Variable name syntax Fortran type Description and default value yP E Number of independent regions
7. 2 0 2 0 Real arrays Geometry based strategy size and shape of the refined region at each level Variables used to perform interpolation pro longation and averaging restriction interpol E ES interpol_var 0 conservatives p pu pE interpol var 1 primitives p pu pe Type of slope limiter used in the interpolation scheme for newly refined cells or for buffer cells int 1_type 0 No int lati traia Boro interpol type o interpolation 21 interpol type 1 MinMod limiter interpol type 2 MonCen limiter interpol type 3 Central slope no limiter 4 Cosmological simulations In this section we describe in more detail how RAMSES can be used to perform cosmological simulations Useful concepts related to parallel computing or post processing will be introduced and can also be used for non cosmological runs Cosmological simulations are performed by specifying cosmo true in the RUN PARAMS namelist 4 1 Parameter file and initial conditions The first thing to do when performing cosmological simulations is to generate initial con ditions as Gaussian random fields The easiest way is to use the freely available grafic2 code developed by Edmund Bertschinger at MIT see http web mit edu edbert or its parallel version mpgrafic developed by Christophe Pichon and Simon Prunet at IAP see http www projet horizon fr These codes will generate initial conditions according to a given cosmological model and for a gi
8. boxlen25_n128 initfile 4 scratchdir grafic_directories boxlen12p5_n128 The re simulation is now ready to go Those are our last words on cosmological simulations and how to run them using only Parameter Files as Runtime Parameters We now describe how to use RAMSES with more advanced settings 27 5 Advanced simulations For truly innovative scientific applications the user is usually forced to define complex initial conditions to impose time varying boundary conditions or to use more than the 5 standard Euler variables chemical species for example We briefly describe the easiest way to do it in RAMSES 5 1 Patching the code The general philosophy to design advanced RAMSES applications is to patch the code What do we mean by that A few key routines have been designed in RAMSES in a user friendly fashion allowing the user to edit the file modify it according to it needs and recompile the code For that it is recommended to create your own directory for example mypatch in which you will copy the various files you plan to modify In the Makefile you need to specify the complete path of this directory in the PATCH variable as PATCH home foo mypatch The make command will seek for sources files in this directory first compile and link them if present If not it will use the default source files already available in the RAMSES package Virtually any RAMSES source file can be modified to obtain a patched
9. two body collisions 20 3 9 Refinement strategy This namelist REFINE_PARAMS is used to specify refinement parameters controlling the AMR grid generation and evolution during the course of the run It is used only if levelmax gt levelmin Variable name syntax and default value Fortran type Description Quasi Lagrangian strategy mass_sph is used mass_sph 0 0 Real to set a typical mass scale For cosmo runs its value is set automatically Quasi Lagrangian strategy each level is re fined if the baryons mass in a cell ex m refine 1 1 1 Real array ceeds m refine ilevel mass sph or if the number of dark matter particles exceeds m refine ilevel whatever the mass is Jeans refinement strategy each level is refined jeans refine 1 1 Real array if the cell size exceeds the local Jeans length divided by jeans refine ilevel floor d 1d 10 Discontinuity based strategy density velocity floor u 1d 10 Real and pressure floor below which gradients are floor p 1d 10 ignored err grad d 1 0 Discontinuity based strategy density velocity err grad u 1 0 Real and pressure relative variations above which a err grad p 1 0 cell is refined x refine 0 0 0 0 0 0 y_refine 0 0 0 0 0 0 z_refine 0 0 0 0 0 0 gt L Real arrays Geometry based strategy center of the refined region at each level of the AMR grid r_refine 1d10 1d10 a_refine 1 0 1 0 b_refine 1 0 1 0 exp_refine
10. u is an output array containing the volume average of the fluid conservative variables namely p pu pv pw and E in this exact order If more variables are defined using the DNVAR directive then the user should exploit this routine to define them too dx is a single real value containing the cell size for all the cells and nce11 is the number of cells This routine can be used to set the initial conditions directly with Fortran instructions Examples of such instructions can be found in directory patch Another way to define initial conditions in RAMSES is by using input files For the hydro solver these files are always in the grafic format We have already explained how to use the grafic format for cosmological runs For non cosmological runs initial conditions can 28 be defined using the exact same format except that instead of 4 files ic_deltab ic_velbx ic_velby and ic_velbz one now needs 5 files called ic_d ic_u ic_v ic_w and ic_p and containing the fluid primitive variables For collisionless particles the grafic format is used only for cosmological runs for which particles are initially placed at the cell centers of a Cartesian grid For non cosmological runs the particles initial positions velocities and masses are read in an ASCII file in which each line corresponds to one particle and should contain the following particle attributes X y Z VX Vy VZ m 5 4 Boundary conditions As explained in the previous se
11. version of RAMSES that fulfill your needs Usually however only a few routines need to be modified in order to perform advanced simulations These routines will be described now in more detail The corresponding files are stored in various RAMSES subdirectories These are amr units f90 hydro boundana f90 hydro condinit f90 poisson gravana f90 poisson rho_ana f90 hydro cooling fine f90 Of course other routines of RAMSES can be modified at will although potential changes might be more complicated to implement A simple example of patch can be found in the directory patch of the package 5 2 Physical units This very simple routine can be found in directory amr and is called units f90 It is used to set the conversion factors from the user units into the cgs unit system In this routine the user must provide 3 scaling factors namely scale_d for the density units in g cm scale_1 for the length scale in cm and scale_t for the time scale in seconds For self gravity runs since RAMSES assumes G 1 in the Poisson equation it is mandatory to define the time scale as scale_t 1 0 sqrt G scale_d with G 6 67d 8 These scaling factors are stored in the output files and can be used later on during post processing 5 3 Initial conditions This routine can be found in directory hydro and is called condinit f90 It is sel documented The calling sequence is just call condinit x u dx ncell where x is an input array of cell center positions
12. 0 ngridmax 10 Gb for pure hydro runs Because of MPI communications overheads the actual memory used can be slightly higher Note that these numbers are valid for double precision arithmetic For single precision runs using the preprocessor directive DNPRE 4 you can decrease these figures by 40 4 3 Restarting a run As we just discussed it is possible to resume a RAMSES run if the execution has stopped abnormally For that RAMSES uses its output files stored in directories called output_00001 output_00002 output 00003 output 00004 23 Each directory contains all the necessary information for RAMSES to resume the execution The frequency at which these output files are created is specified by parameter foutput in units of coarse time steps If you want to resume the execution starting from output directory number 4 you need to specify the corresponding number in parameter nrestart 4 If you set nrestart 0 the run will start from the beginning as a completely new run When restarting a job you can change almost all run parameters There are however some notable exceptions The number of output times can only be increased and only new output times can be added after the old ones The number of processors used with MPI cannot change If you want to change the number of processes you should start from the very beginning 4 4 Parallel computing We are now ready to address the complex issue of parallel computing with RAM
13. 3 20 pressure_fix 18 r_bubble 19 r_refine 21 region_type 15 riemann2d 18 riemann 18 slope_type 18 smallc 18 smallr 18 t_star 19 tend 16 tout 16 u_bound 17 29 u_region 15 v_bound 17 v_region 15 verbose 13 w_bound 17 w_region 15 x_center 15 x_refine 21 y_center 15 y_refine 21 yield 19 z_ave 19 z_center 15 z_refine 21 z_reion 19 solvers acoustic Riemann solver 18 diff solver 6 exact Riemann solver 18 hllc Riemann solver 18 hlld Riemann solver 18 h11 Riemann solver 18 hydro Riemann solver 18 hydro solver 6 11f Riemann solver 18 33 mhd solver 6 rad solver 6 roe Riemann solver 18 upwind Riemann solver 18 utilities amp directories amr directory 6 22 24 28 amr2cube utility 26 amr2map utility 26 bin directory 6 center grafic utility 27 degrade grafic utility 27 extract grafic utility 27 grafic2 package 22 grafic package 27 29 hydro directory 6 28 30 mpgrafic package 4 22 27 namelist directory 7 9 17 22 output_00001 directory 24 part2cube utility 26 part2map utility 26 patch directory 28 poisson directory 30 ramses directory 6 sod utility 27 utils f90 directory 26 27 utils idl directory 26
14. Do not forget to recompile entirely the code make clean then make with NDIM 2 for 2D cases like sedov2d nml or NDIM 3 for 3D cases such as sedov3d nml In the next section we will describe in more detail the various Runtime Parameters available within RAMSES A 0 0 O a ca cac HT 0 0 0 2 0 4 0 6 0 8 1 0 Level 10 1 0 0 0L 0 4 0 6 0 8 1 0 AA T T 34 0 0 0 2 0 4 0 6 0 8 1 0 Figure 1 Numerical results obtained with RAMSES for the Sod shock tube test symbols compared to the analytical solution red line 10 3 Runtime Parameters The RAMSES parameter file is based on the Fortran namelist syntax The Sod test parameter file is shown below as it should appear if you edit it This is the RAMSES parameter file for Sod s shock tube test 30 31 32 33 34 36 37 38 39 40 Al 42 43 44 46 amp RUN_PARAMS hydro true nsubcycle 3 1 2 amp AMR PARAMS levelmin 3 levelmax 10 ngridmax 2000 nexpand 1 boxlen 1 0 amp BOUNDARY PARAMS nboundary 2 ibound_min 1 1 ibound max 1 1 bound type 1 1 de amp INIT PARAMS nregion 2 region type 1 square region type 2 square x center 0 25 0 75 length x 0 5 0 5 d region 1 0 0 125 u region 0 0 0 0 p_re
15. S block 12 20 amp REFINE PARAMS block 12 14 21 amp RUN_PARAMS block 12 13 22 24 namelist parameters amp log entries J21 19 T2 star 19 50 a refine 21 a spec 19 aend 16 aexp ini 15 angular 13 aout 16 a log entry 9 b refine 21 bound type 17 29 30 boxlen 14 22 cg levelmin 20 cic levelmax 20 cooling 19 30 cosmo 13 22 courant_factor 18 d_bound 17 29 d_region 15 del_star 19 delta_tout 16 econs log entry 9 eps_star 19 epsilon 20 err_grad_d 21 err_grad_p 21 err_grad_u 21 32 eta_sn 19 exp_refine 21 exp_region 15 f_ek 19 f_w 19 filetype 15 22 floor_d 21 floor_p 21 floor_u 21 foutput 16 24 g_star 19 gamma 18 gravity params 20 gravity type 20 haardt madau 19 hilbert 13 hydro 13 ibound max 17 ibound min 17 initfile 15 22 interpol type 21 interpol var 21 isothermal 19 jbound max 17 jbound min 17 jeans refine 21 kbound max 17 kbound min 17 length x 15 length y 15 length z 15 levelmax 9 13 14 21 levelmin 8 13 14 21 22 m refine 21 mass sph 21 mcons log entry 9 metal 19 multiple 15 n star 19 nboundary 17 ncontrol 13 ndebris 19 nexpand 14 ngridmax 14 23 ngridtot 14 23 niter riemann 18 noutput 16 npartmax 14 23 nparttot 14 23 nregion 15 nremap 13 24 nrestart 13 24 nstepmax 13 nsubcycle 13 ordering 13 24 p_bound 17 p_region 15 pic 13 20 planar 13 poisson 1
16. SES It is based on the MPI library through regular calls of MPI communication routines In order to compile and link RAMSES with the MPI library you need first to remove the preprocessor directive DWITHOUTMPI from the compilation options in the Makefile Don t forget to type make clean and then make again In order to launch a parallel RAMSES run type for example mpirun np 4 bin ramses3d namelist sedov3d nml The two key parameters for parallel runs are nremap and ordering both contained in the amp RUN_PARAMS namelist block The first one specifies the frequency at which the code will optimize load balancing by adjusting the domain decomposition in units of coarse time step Since it is a rather costly operation this should not be performed too frequently On the other hand if the AMR grid evolves significantly with time the computational and memory load might be very inhomogeneous across the processors The optimal choice for parameter nremap is therefore application dependent Bear in mind that if nremap gt 10 the associated overhead should be negligible The other important parameter for an efficient parallel computing strategy is ordering This character string specifies the type of domain decomposition you want to use There are 3 possible choices in RAMSES currently implemented hilbert default value planar and angular Each cell in RAMSES is ordered with an integer index according to a given space ordering One of
17. _files amp AMR_PARAMS levelmin 7 22 levelmax 14 ngridtot 2000000 nparttot 3000000 nexpand 1 amp REFINE_PARAMS m_refine 7 8 Parameters ngridtot and nparttot specify the maximum memory allocated for AMR grids and collisionless particles respectively These numbers should be greater than or equal to the actual number of AMR grids and particles used during the course of the simulation ngridtot stands for the total number of AMR grids allocated over all MPI processes The ngridmax parameter can be used equivalently but stands for the local number of AMR grids within each MPI process Obviously one has ngridtot ngridmax ncpu Recall that in RAMSES we call AMR grid or oct a group of 2 42 cells If for some reason during the course of the execution the maximum allowed number of grids or particles has been reached the simulation stops with the message No more free memory Increase ngridmax In this case don t panic just increase ngridmax in the Parameter File and resume the execution starting from the last valid output file 4 2 Memory management These two parameters control the memory allocated by RAMSES It is important to know how much memory in Gb is actually allocated by RAMSES for a given choice of parameters This can be approximated by e 0 7 ngridmax 10 0 7 npartmax 10 Gbytes for pure N body runs e 1 4 ngridmax 10 0 7 npartmax 107 Gb for N body and hydro runs e 1
18. agement and MPI communications while hydro obviously contains all F90 routines dealing with hydrodynamics The first directory you are interested in is the bin directory in which the code will be compiled 2 2 Compiling the code In this bin directory you will find a Makefile The first thing to do is to edit the Makefile and modify the two variables F90 and FFLAGS Several examples corresponding to different Fortran compilers are given The default values are F90 pgf90 FFLAGS Mpreprocess DWITHOUTMPI DNDIM NDIM DSOLVER SOLVER The first variable is obviously the command used to invoke the Fortran compiler In this case this is the Portland Group compiler The second variable contains Fortran flags and preprocessor directives The first directive DWITHOUTMPI when used switches off all MPI routines On the other hand if you don t use this directive the code must be linked to the MPI library We will discuss this point later Theses directives are called Compilation Time Parameters They should be defined within the Makefile Default values are NDIM 1 SOLVER hydro The first variable NDIM sets the dimensionality of the problem The default value is for 1D plan parallel flows Allowed values are 1 2 and 3 The second directive defines the solver which in the current release of RAMSES can be hydro or mhd Other solvers are currently under development such as rad diff and so on There are 3 other preprocessor directive
19. ctions RAMSES can provide boundary conditions of different types periodic default mode reflexive outflow and imposed This is performed in RAMSES using ghost regions in which the fluid variables are set in order to obtain the required boundary Ghost regions are defined in the namelist block BOUNDARY_PARAMS Each region is identified by its position its type and eventually by the value of the fluid variables The exact order with which boundary regions are entered in the namelist block is very important Let us consider the 4 boundary regions shown in figure 3 They are defined by the following namelist block amp BOUNDARY PARAMS nboundary 4 ibound_min 1 1 1 1 ibound_max 1 1 1 1 jbound_min 0 0 1 1 jbound_max 0 0 1 1 bound_type 1 1 1 1 The first region is located in the rectangle defined by coordinate i 1 j 0 while the third region is defined by coordinates 1 lt i lt 1 j 1 The boundary type for all 4 regions is set to reflexive bound_type 1 The fluid variables within the ghost region are there fore taken equal to the values of their symmetric cells with respect to the boundary This is why the order of the ghost regions is so important re gions 1 and 2 are updated first using only the fluid variables within the computational domain Regions 3 and 4 are updated afterwards using the fluid variables within the computational domain but also within regions 1 and 2 In this way a
20. e St phane Colombi and St phanie Courty cooling and atomic physics Yann Rasera star formation post processing Yohan Dubois supernovae feedback e Thomas Guillet multigrid Poisson solver e S bastien Fromang Patrick Hennebelle and Emmanuel Dormy MHD solver e Philippe Wautelet and Philippe S ri s code optimization I would like to thank my collaborators for helping me developing more advanced versions of RAMSES not yet available as complete releases since it is mostly work in progress s Benoit Commercon thermal conduction e Edouard Audit and Dominique Aubert radiative transfer e R mi Abgrall and Richard Saurel multifluid 1 5 The CeCILL License This software is under Copyright of CEA and its author Romain Teyssier This software is governed by the CeCILL license under French law and abiding by the rules of distribution of free software You can use modify and or redistribute the software under the terms of the CeCILL license as circulated by CEA CNRS and INRIA at the following URL http www cecill info As a counterpart to the access to the source code and rights to copy modify and redistribute granted by the license users are provided only with a limited warranty and the software s author the holder of the economic rights and the successive licensors have only limited liability In this respect the user s attention is drawn to the risks associated with loading using modifying and or developing or re
21. er Slope type 3 Multi dimensional MonCen limiter In 1D runs only it is also possible to choose slope type 4 Superbee limiter Slope type 5 Ultrabee limiter Activate hybrid scheme conservative or prim pressure fix false Logical itive for high Mach flows Useful to prevent negative temperatures 18 3 7 Physical parameters This namelist called 4PHYSICS_PARAMS is used to specify physical quantities used in cosmolog ical applications cooling star formation and supernovae feedback We briefly describe them now Variable name syntax and default value cooling false Fortran type Logical Description Activate the cooling and or heating source term in the energy equation isothermal false Logical Enforce isothermal equation of state The con stant temperature is taken equal to the one given by the polytropic equation of state see below metal false Logical Activate metal enrichment advection and cool ing In this case the preprocessor directive DNVAR 6 should be added in the Makefile be fore the compilation haardt_madau false Logical Use the UV background model of Haardt and Madau Default value false corresponds to a simple analytical model with parameters J21 and a_spec J21 0 0 a_spec 1 0 Real Real Normalization for the UV flux of the simple background model Default means no UV Slope for the spectrum of the simple back ground
22. es If bound_type 3 boundary conditions must be imposed also for the gravitational force This is performed by modifying routine gravana f90 in directory poisson If gravity_type gt 0 this routine is also used to specify the gravitational force within the computational domain Note that in this case the fluid is not self gravitating anymore There is another way to impose an external gravity source and in the same time to solve for the Poisson equation This is done using routine rho_ana f90 in directory poisson In this routine again very similar to the previously presented Fortran routines the user can specify the density profile for the external gravity source This density profile will be added to the fluid density as the source term in the Poisson equation 5 6 External thermal sources The final routine that can be easily modified by the user is cooling fine f90 in directory hy dro This routine is used if cooling true or if the polytropic temperature T2_star gt 0 0 In the first case cooling and heating source terms are added to the energy equation and solved by a fully implicit integration scheme In the second case the thermal energy of the fluid is not allowed to be lower than a polytropic Equation Of State for which one has T p T 1 p px All starred parameters can be set within the namelist block amp PHYSICS_PARAMS On the other hand the user might want to modify routine cooling fine f90 in order to im plement more c
23. example of interactive com mands you need to type within your IDL session to watch RAMSES data for example using sedov2d nml IDL gt rd_amr a nout 2 Read AMR data from snapshot nr 2 and store in a IDL gt rd_hydro h nout 2 Read hydro data and store in variable h IDL gt window 0 xs 512 ys 512 Set up a square window IDL gt loadct 33 Load a nice color table IDL gt tv2d a h type 1 log show Plot a density map with the grid Here is another example to plot a density profile from the previous data IDL gt amr2cell a h c Convert AMR data into cell based data IDL gt r sqrt c x 2 c y 2 Compute cell radius IDL gt d c var 0 Compute cell density IDL gt plot r d psym 6 For 3D data you can use a simple raytracing algorithm to project various quantities along one of the box principal axis IDL gt ray3d a h lmin 7 1max 9 zproj ave type 1 log Project the average density along the z axis 26 4 6 Zoom simulations Another interesting cosmological application for RAMSES is the so called zoom technology or re simulation process Let us consider the large scale periodic box simulation we have pre sented in the previous section performed with 128 particles by RAMSES with the grafic files stored in directory scratchdir grafic_files After using the sod application all dark mat ter halos in the final output have been identified One halo is believed to be a good candidate for re simulation A quasi sp
24. gion 1 0 0 1 amp OUTPUT PARAMS noutput 1 tout 0 245 amp HYDRO_PARAMS gamma 1 4 courant_factor 0 8 slope_type 2 scheme muscl amp REFINE PARAMS 11 47 48 49 err_grad_d 0 05 err_grad_u 0 05 err_grad_p 0 05 interpol_var 0 interpol_type 2 This parameter file is organized in namelist blocks Each block starts with amp BLOCK_NAME and ends with the character Within each block you can specify parameter values using standard Fortran namelist syntax There are currently 9 different parameter blocks implemented in RAMSES 4 parameter blocks are mandatory and must always be present in the pa rameter file These are amp RUN_PARAMS amp AMR_PARAMS amp OUTPUT PARAMS and amp INIT PARAMS The 5 other blocks are optional They must be present in the file only if they are rel evant to the current run These are amp BOUNDARY PARAMS HYDRO_PARAMS amp PHYSICS PARAMS amp POISSON_PARAMS and finally amp REFINE PARAMS We now describe each parameter block in more detail 12 3 1 Global parameters This block called amp RUN PARAMS contains the run global control parameters These parameters are now briefly described More thorough explanations will be given in dedicated sections Variable name syntax Fortran type Description and default value T E Activate cosmological super comoving coordi false Logical kad aera NEN nates system and expansion factor co
25. grid MG Unlike the CG solver MG has an initialization overhead cost at every call of the solver but is much more efficient on very big levels with few holes The multigrid solver is therefore used for all coarse levels In addition MG can be used on refined levels in conjuction with CG The parameter cg_levelmin selects the Poisson solver as follows e Coarse levels are solved with MG e Refined levels with lt cg_levelmin are solved with MG e Refined levels with gt cg_levelmin are solved with CG Variable name syntax Fortran type Description and default value N P Type of gravity force Possible choices are gravity type 0 self gravity Poisson solver gravity type 0 Integer gravity type 0 analytical gravity vector gravity type 0O self gravity plus additional analytical density profile Stopping criterion for the iterative Poisson epsilon 1d 4 Real solver residual 2 norm should be lower than epsilon times the right hand side 2 norm Parameters used to define the analytical gravity A e Real array field routine gravana f90 or the analytical S 19505 mass density field routine rho ana 90 Minimum level from which the Conjugate Gra cg levelmin 999 Integer dient solver is used in place of the Multigrid solver Maximum level above which no CIC interpo cic Ye elnaz 999 eds lation is performed for dark matter particles This allows to have very high level of refinement without suffering from
26. herical region must be determined whose size and position are optimized in order to contain all the particles ending up in the final halo A new set of initial conditions must then be generated using mpgrafic providing the same large scale modes than the previous run but allowing now to simulate up to 10247 particles A suite of applications is available in directory utils f90 to perform the extraction of a high resolution region con taining the halo particles only These codes are called center grafic extract grafic and degrade grafic The idea is to center the simulation box on the high resolution region to ex tract a nested collection of rectangular grids around this position with various particle masses The initial conditions data for each box are stored in a different directory The original data centered on the region center can be called boxlen100_n256 where 100 stands for the box size in k Mpc and 128 for the number of particles per box length The nested box hierarchy we obtained using our various utilities is now boxleni00 n128 boxlen50_n128 boxlen25_n128 boxlen12p5_n128 Each of these directories should contain 7 grafic files These names should be now inserted in the Parameter File in the amp INIT PARAMS block as amp INIT PARAMS filetype grafic initfile 1 scratchdir grafic_directories boxlen100_n128 initfile 2 scratchdir grafic_directories boxlen50_n128 initfile 3 scratchdir grafic_directories
27. ilding initial AMR grid Initial mesh structure Level 1 has 1 grids f 1 1 Level 2 has 2 grids 2 2 2 Level 3 has 4 grids 4 4 4 Level 4 has 8 grids 8 8 8 Level 5 has 8 grids 8 8 8 Level 6 has 8 grids 8 8 8 Level 7 has 8 grids 8 8 8 Level 8 has 8 grids 8 8 8 Level 9 has 6 grids 6 6 6 Level 10 has 4 grids 4 4 4 Starting time integration Output 58 cells lev x d u P 4 3 12500E 02 1 000E 00 0 000E 00 1 000E 00 4 9 37500E 02 1 000E 00 0 000E 00 1 000E 00 4 9 06250E 01 1 250E 01 0 000E 00 1 000E 01 4 9 68750E 01 1 250E 01 0 000E 00 1 000E 01 Fine step O t 0 00000E 00 dt 6 603E 04 a 1 000E 00 mem 3 2 Fine step 1 6 60250E 04 dt 4 453E 04 a 1 000E 00 mem 3 2 After the code banner and copyrights the first line indicates that you are currently using 1 processor and 1 space dimension for this run The code then reports that it is building the initial AMR grid The next lines give the current mesh structure The first level of refinement in RAMSES covers the whole computational domain with 2 4 or 8 cells in 1 2 or 3 space dimensions The grid is then further refined up to levelmin which is this case is defined in the parameter file to be levelmin 3 The grid is then further refined 1281 1282 1283 1284 1285 1286 1287 1288 up to levelmax which is in this case levelmax 10 Each line in the Log File indicates the number of octs or grids at each level of
28. in step This Control Line gives information on each Coarse Step namely its current number the current error in mass conservation within the computational box mcons the current error in total energy conservation econs the gravitational potential energy and the fluid total energy kinetic plus thermal This constitutes the basic information contained in the Log File In 1D simulations output data are also written to standard output and thus to the Log File For 2D and 3D output data are stored into unformatted Fortran binary files 1D data are shown using 5 columns level of refinement position of the cell density velocity and pressure as in the following Sod s test example Output 143 cells lev x d u P 5 1 56250E 02 1 000E 00 0 000E 00 1 000E 00 5 4 68750E 02 1 000E 00 0 000E 00 1 000E 00 5 7 81250E 02 1 000E 00 0 000E 00 1 000E 00 5 1 09375E O01 1 000E 00 1 896E 09 1 000E 00 6 1 32812E 01 1 000E 00 2 536E 08 1 000E 00 You can cut and paste the 148 lines into another file and use your favorite data viewer like xmgrace or gnuplot to visualize the results These should be compared to the plots shown on Figure 1 If you have obtained comparable numerical values and levels of refinements your installation is likely to be valid You are encouraged to edit the parameter file tube1d log and play around with other parameter values in order to test the code performances You can also use other Parameter Files in the namelist directory
29. in the compu HERSES GEE tational box used to set up initial flow variables Geometry defining each region square defines a generalized ellipsoidal shape while point de fines a delta function in the flow Character region_type square LEN 10 array x_center 0 y_center 0 z_center 0 Real arrays Coordinates of the center of each region length_x 0 length_y 0 length_z 0 0 0 0 0 0 Real arrays Size in all directions of each region 0 Exponent defining the norm used to com pute distances for the generalized ellip exp region 2 0 Real array soid exp region 2 corresponds to a spheroid exp region 1 to a diamond shape exp region 10 to a perfect square d region 0 u_region 0 0 0 Flow variables in each region density veloc v_region 0 0 Real arrays 0 0 ities and pressure For point regions these variables are used to defined extensive quanti ion 0 gti rie ties mass velocity and specific pressure p_region 0 Character Type of initial conditions file for particles Pos filet ii Sa SO LEN 20 sible choices are ascii or grafic This parameter sets the starting expansion fac aexp_ini 10 0 Real tor for cosmology runs only Default value is read in the IC file grafic or ascii If true each processor reads its own IC file ltiple false Logical hor ab deri n i sup grafic or ascii For parallel runs only
30. initial conditions leen 12 Memory management usioe sw soaa RR E X ec Rmo Xo eee e m RR AS o RESTAN DA E es a oth E ae RR ae ATR ad E a a a4 Parallel computine soa ue Roe oe bee c eo um K A ee NR RE Rin 45 Postprocessing ODER Ge ek a owe RECTOR Wok oe a tl uoo oa go Yo x Xem ovi ome e Ecao oe eee we 5 Advanced simulations D Patching T Ber enie wan b aia aC E heu a se a SEDE wk ee da R a oc ee erc RU RR RA ek ee R RTE ee E S B tal COn HONS ea ak RR K em ROE RR oe ee ee E E uA ba Boundary cOndiboHe A ae xe RR T NRT ee E oe REUS OR T IECUR RA 5 5 External gravity SOUPC B 4 ccoo ceo Romo m a y R 5 6 Externalthermalsources s sea 2 22 lt e o Ro e 6 Publication policy Index 11 13 14 15 16 17 18 19 20 21 22 22 23 23 24 26 27 28 28 28 28 29 30 30 31 32 1 Introduction The RAMSES package is intended to be a versatile platform to develop applications using Adaptive Mesh Refinement for computational astrophysics The current implementation allows solving the Euler equations in presence of self gravity and cooling treated as additional source terms in the momentum and energy equations The RAMSES code can be used on massively parallel architectures when properly linked to the MPI library It can also be used on single processor machines without MPI Output files are generated using native RAMSES Fortran unformatted files A suite of post processing routines is delivered within the p
31. ll cells within boundary regions are properly defined especially in the 4 corners of the computational domain It is possible to define only 2 regions say regions 1 and 2 in figure 3 the orthogonal direction will be considered as periodic For gravity runs the gravitational force is also updated in the ghost regions following the same rules as the velocity vector For the Poisson equation however boundary conditions are either periodic if no ghost regions are defined in the corresponding direction or fp 0 Dirichlet boundary conditions within ghost regions No other types of boundary conditions for the Poisson equation have been implemented such as isolated reflexive and so on If bound type 3 boundary conditions must be imposed by the user The first possibility is to use parameters d bound u bound to set a constant fluid state within the desired 29 Boundary region 3 Boundary Computational Boundary region 1 domain region 2 Boundary region 4 Figure 3 Example of ghost regions used in RAMSES to impose specific boundary conditions ghost region For more advanced applications the user is encouraged to patch the routine boundana f90 within directory hydro This routine is very similar to routine condinit f90 The calling sequence is call boundana x u dx ibound ncell The ghost region number is therefore provided so the user can specify some region dependent fluid conditions 5 5 External gravity sourc
32. model Default value corresponds to a standard quasars OB stars spectrum z_reion 8 5 Real Reionization redshift for the UV background model z_ave 0 0 Real Average metallicity used in the cooling func tion in case metal false t_star 0 0 eps_star 0 0 Real Star formation time scale in Gyr at the den sity threshold or star formation efficiency De fault value of zero means no star formation n_star 0 1 del_star 200 Real Typical interstellar medium physical density or comoving overdensity used as star formation density threshold and as EOS density scale T2_star 0 0 g_star 1 6 eta_sn 0 0 yield 0 1 Real Real Typical interstellar medium polytropic EOS parameters Mass fraction of newly formed stars that ex plode into supernovae Default value of zero means no supernovae feedback f_w 10 0 r_bubble 0 Real Mass loading factor and supernovae bubble ra dius in pc ndebris 1 f_ek 1 Integer Real 19 Use debris particles or grid cells if set to zero to set the blast wave model for supernovae feed back Fraction of the supernovae energy that goes into kinetic energy of the gas 3 8 Poisson solver This namelist amp POISSON PARAMS is used to specify runtime parameters for the Poisson solver It is used only if poisson true or pic true Two different Poisson solvers are available in RAMSES conjugate gradient CG and multi
33. mputing pic false Logical Activate Particle In Cell solver poisson false Logical Activate Poisson solver hydro false Logical Activate hydrodynamics or MHD solver verbose false Logical Activate verbose mode Output file number from which the code loads backup data and resumes the simulation The default value zero is for a fresh start from the nrestart 0 Integer nae beginning You should use the same number of processors than the one used during the previ ous run nstepmax 1000000 Integer Maximum number of coarse time steps t nieke Frequency of screen output for Control Lines to standard output into the Log File Frequency of calls in units of coarse time steps nremap 0 Integer for the load balancing routine for MPI runs only the default value zero meaning never Cell ordering method used in the domain de Character composition of the grid among the processors LEN 128 for MPI runs only Possible values are hilbert planar and angular ordering hilbert Number of fine level sub cycling steps within one coarse level time step Each value corre sponds to a given level of refinement starting from the coarse grid defined by levelmin up nsubcycle 2 2 2 2 2 Integer array to the finest level defined by levelmax For ex ample nsubcycle 1 1 means that levelmin and levelmin 1 are synchronized To enforce single time stepping for the whole AMR hier archy you need to set nsubcycle 1 1 1 1 1
34. omplex thermal modeling of the fluid 30 6 Publication policy The RAMSES code is freely available for non commercial use under the CeCILL License agree ment If a paper is published with simulations performed with RAMSES the authors should cite the following paper in which the RAMSES code was presented for the first time Teyssier Romain Cosmological hydrodynamics with Adaptive Mesh Refinement a new high resolution code called RAMSES Astronomy and Astrophysics 2002 volume 885 page 337 If the same users need some basic help from the author on how to use RAMSES or if the simulations performed have needed from the code s author some small adaptation of the code a small sentence like We thank Romain Teyssier for in the Acknowledgment section will do it If on the other hand the simulations performed requires the code s author to be more deeply involved in the project new developments new simulations from the author s side then co authorship of the paper is asked 31 Index makefile options and flags F90 option 6 FFLAGS option 6 NDIM option 6 9 NPRE option 6 23 NVAR option 6 19 28 NVECTOR option 6 PATCH option 28 WITHOUTMPI option 6 24 namelist blocks amp AMR_PARAMS block 12 14 amp BOUNDARY_PARAMS block 12 17 29 amp HYDRO_PARAMS block 12 18 amp INIT PARAMS block 12 15 22 27 amp OUTPUT PARAMS block 12 16 amp PHYSICS_PARAMS block 12 19 30 amp POISSON PARAM
35. producing the software by the user in light of its specific status of free software that may mean that it is complicated to manipulate and that also therefore means that it is reserved for developers and experienced professionals having in depth IT knowledge Users are therefore encouraged to load and test the software s suitability as regards their requirements in conditions enabling the security of their systems and or data to be ensured and more generally to use and operate it in the same conditions as regards security The fact that you are presently reading this means that you have had knowledge of the CeCILL license and that you accept its terms 2 Getting started In this section we will explain step by step how to get the RAMSES package and install it then how to perform a simple test to check the installation 2 1 Obtaining the package The package can be downloaded from the web site http www dapnia cea fr Projets COAST in the Codes section You will get a tar ball named ramses tar gz The first thing to do is to un tar the archive on your preferred computer s home directory gunzip ramses tar gz tar xvf This will create a new directory named ramses In this directory you will find the following directory list amr bin doc hydro mhd namelist patch pm poisson utils Each directory contains a set of files with a given common purpose For example amr con tains all F90 routines dealing with the AMR grid man
36. projet horizon fr It is freely distributed under the CeCILL software license see section 1 5 and http www cecill info according the French legal system for non commercial use only For commercial use of RAMSES please contact the author be prepared for a massive financial compensation 1 3 Main features RAMSES contains various algorithms designed for e Cartesian AMR grids in 1D 2D or 3D Solving the Poisson equation with a Multi grid and a Conjugate Gradient solver e Using various Riemann solvers Lax Friedrich HLLC exact for adiabatic gas dynamics e Computing collision less particles dark matter and stars dynamics using a PM code e Computing the cooling and heating of a metal rich plasma due to atomic physics processes and an homogeneous UV background Haardt and Madau model e Implementing a model of star formation based on a standard Schmidt law with the tradi tional set of parameters e Implementing a model of supernovae driven winds based on a local Sedov blast wave solution All these features can be used and parameterized using the RAMSES parameter file based on the Fortran namelist format 1 4 Acknowledgements The development of the RAMSES code has been initiated and coordinated by the author The author would like to thank all collaborators who took an active role in the development of this version They are cited in chronological order e Matthias Gonzalez and Dominique Aubert initial conditions
37. refinement The maximum number of grids in each level 1 is equal to 2 7 in 1D to 47 in 2D and to 8 in 3D The numbers inside parentheses give the minimum maximum and average number of grids per processor This is obviously only relevant to parallel runs The code then indicates the time integration starts After outputting the initial conditions to screen the first Control Line appears starting with the words Fine step The Control Line gives information on each Fine Step its current number its current time coordinate its current time step Variable a is for cosmology runs only and gives the current expansion factor The last variable is the percentage of allocated memory currently used by RAMSES to store each flow variable on the AMR grid and to store each collision less particle if any In RAMSES adaptive time stepping is implemented which results in defining Coarse Steps and Fine Steps Coarse Steps correspond to the coarse grid which is defined by variable levelmin Fine Steps correspond to finer levels for which the time step has been recursively subdivided by a factor of 2 Fine levels are sub cycled twice as more as their parent coarse level This explains why at the end of the Log File only 43 Coarse Steps are reported 1 through 43 for 689 Fine Steps numbered 0 to 688 When a Coarse Step is reached the code writes in the Log File the current mesh structure A new Control Line then appears starting with the words Ma
38. resent release allowing the user to perform a simple analysis of the generated output files 1 1 About This Guide The goal of this User s Guide is to provide a step by step tutorial in using the RAMSES code This guide will first describe a simple example of its use More complex set up will be addressed at the end of the document Typical RAMSES users can be grouped into 3 categories e Beginners It is possible to execute RAMSES using only run parameter files The code is compiled once and the user only modifies the input file to perform various simulations Cosmological simulations can be performed quite efficiently in this way using the initial conditions generated by external packages such as mpgrafic e Intermediate users For more complex applications the user can easily modify a small set of routines in order to specify specific initial or boundary conditions These routines are called patches and the code should be recompiled each time these routines are modified e Advanced users It is finally possible to modify the base scheme add new equations or add new routines in order to modify the default RAMSES application This guide will not describe these advanced features In this case a new documentation would be given separately 1 2 Getting RAMSES RAMSES software can be downloaded in the Codes section from various web sites the most frequently updated ones being http www dapnia cea fr Projets COAST and http www
39. rresponding section The default setting corresponding to a periodic box should be sufficient in most cases The strategy to set up boundary conditions is based on using ghost regions outside the computational domain where flow variables are carefully specified in order to mimic the effect of the chosen type of boundary Note that the order in which boundary regions are specified in the namelist is very important especially for reflexive or zero gradient boundaries See section 5 4 for more information on setting up such boundary conditions Specific examples can be found in the namelist directory of the package Variable name syntax Fortran type Description and default value Number of ghost regions used to specify the nboundary 1 Integer boundary conditions Type of boundary conditions to apply in the corresponding ghost region Possible values are bound_type 0 0 0 Integer array bound_type 0 periodic bound type 1 reflexive bound type 2 outflow zero gradients bound type 3 inflow user specified d bound 0 0 u_bound 0 0 Flow variables in each ghost region density ve v_bound 0 0 Real arrays locities and pressure They are used only for w_bound 0 0 inflow boundary conditions p_bound 0 0 Coordinates of the lower left bottom corner of each boundary region Each coordinate lies be tween 1 and 1 in each direction see figure 3 on page 30 ibound_min 0 jbound_min 0 Integer arrays kbound_min 0
40. s that can be use in RAMSES DNVAR NDIM 2 useful to set more variables in the hydro solver DNPRE 8 to set the number of bytes used for real numbers NPRE 8 corresponds to double precision arithmetic and NPRE 4 to single precision This option is useful to save memory during memory intensive runs Finally you can use DNVECTOR 500 to set the size of the vector sweeps for computationally intensive operations 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 The optimal size for vector operations is machine dependant It can be anything between say 4 and 8192 To compile RAMSES execute make If everything goes well all source files will be compiled and linked into an executable called ramsesid 2 3 Executing the test case To test the compilation you need to execute a simple test case Go up one level and type the following command bin ramsesid namelist tubeid nml The first part of the command is the executable and the second part the only command line argument is an input file containing all Run Time Parameters Several examples of such param eter files are given in the namelist directory The run we have just performed tubeid nml is the Sod s test a simple shock tube simulation in 1D For comparison we now show the last 14 lines of standard output Mesh structure Level 1 has 1 grids f di 1 Level 2 has 2 grids 2 2 2 Level 3 has 4 grids 4
41. the most famous ordering used in computer science is the Peano Hilbert space filling curve This is a one dimensional object filling up the three dimensional space An example of such domain decomposition is shown in figure 2 This strategy is known to be the optimal choice if one considers the rather large ensemble of all possible AMR grids In some cases however it is no longer an efficient strategy The planar decomposition for example sets up computational domains according to one coordinate only the altitude z for example Each processor receives a layer of cells whose thickness is automatically adjusted in order to optimize load balance The angular decomposition follows the same strategy except that now the coordinate is the polar angle around a given axis in the simulation box These various orderings can be adapted easily to account for specific constraints The user is encouraged to edit and modify the routine load balance f90 in directory amr In case of parallel execution RAMSES performs hard disk outputs in a very simple way each processor creates its own file Therefore in directory output 00001 one can find several files with a numbering corresponding to the processor number One should bear this in mind when using the snapshots generated by RAMSES 24 ion of the unit square for a 32 grid over 7 processors using the Peano Hilbert space filling curve shown as the continuous line Domain decomposit Figure 2 25
42. ven box size As outputs 7 files will be generated called ic deltab ic velcx ic velcy ic velcz ic velbx ic velby and ic velbz The directory in which these files are stored should be entered in the Parameter File as parameter initfile 1 in namelist INIT_PARAMS Index 1 stands here for levelmin and corresponds to the coarse grid RAMSES will automatically read the cosmological parameters and the physical box length contained in these initial conditions files The so called super comoving coordinate system is used in RAMSES for cosmological runs see Martell amp Shapiro 2003 If necessary the translation from this scale free coordinate system boxlen 1 0 to the cgs system is per formed using scaling factors stored in the output files The units are set in routine units f90 in directory amr The following namelist can be found in directory namelist in the RAMSES package as file cosmo nml It is the Parameter File for a pure N body simulation using 128 particles and a 128 coarse grid with 7 additional levels of refinement To specify that initial conditions are to be read in grafic files filetype grafic should be set in namelist ZINIT_PARAMS amp RUN_PARAMS cosmo true pic true poisson true nrestart 0 nremap 10 nsubcycle 1 2 ncontrol 1 amp OUTPUT_PARAMS foutput 10 noutput 10 aout 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 1 0 amp INIT_PARAMS filetype grafic initfile 1 scratchdir grafic
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