<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><br class=""></div><div class="">Hi everyone,</div><div class=""><br class=""></div><div class="">if you want the gas to be exactly isothermal (instead of setting gamma close to unity), you can use the physics/sourceTerms/Polytrope/PolytropeMain module, which is automatically linked in from the setup </div><div class="">Simulation/SimulationMain/StirFromFile. Detailed information on how to use the StirFromFile unit are provided in the FLASH user guide, sections 16.3.2, 16.3.3, and 16.3.4.</div><div class=""><br class=""></div><div class=""><div class="">These modules were used in a number of recent papers. Here are a few examples:</div><div class=""><a href="http://adsabs.harvard.edu/abs/2010A&A...512A..81F" class="">http://adsabs.harvard.edu/abs/2010A%26A...512A..81F</a></div><div class=""><a href="http://adsabs.harvard.edu/abs/2008ApJ...688L..79F" class="">http://adsabs.harvard.edu/abs/2008ApJ...688L..79F</a></div><div class=""><a href="http://adsabs.harvard.edu/abs/2013MNRAS.436.1245F" class="">http://adsabs.harvard.edu/abs/2013MNRAS.436.1245F</a></div><div class=""><a href="http://adsabs.harvard.edu/abs/2015MNRAS.448.3297F" class="">http://adsabs.harvard.edu/abs/2015MNRAS.448.3297F</a></div><div class=""><br class=""></div><div class="">I hope it helps. Please let me know if you have any questions.</div></div><div class=""><br class=""></div><div class="">Cheers,</div><div class="">Christoph</div><div class=""><br class=""></div><div class=""><div class=""><div style="font-variant-ligatures: normal; font-variant-east-asian: normal; font-variant-position: normal;" class="">—</div><div style="font-variant-ligatures: normal; font-variant-east-asian: normal; font-variant-position: normal;" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Christoph Federrath</div><div class=""><a href="http://www.mso.anu.edu.au/~chfeder" class="">http://www.mso.anu.edu.au/~chfeder</a></div><div class=""><br class=""></div></div></div></div></div><br class=""><div class=""><blockquote type="cite" class=""><div class="">On 30 Mar 2017, at 06:45, <a href="mailto:seyit@mpe.mpg.de" class="">seyit@mpe.mpg.de</a> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="">Dear Kezman,<br class=""><br class="">This is an easy one. You shouldn't set gamma exactly equal to 1.0. Some<br class="">equations contain the factor (gamma-1). To achieve isothermality, just<br class="">make gamma close to one, like 1.001.<br class=""><br class="">Best wishes,<br class="">Seyit<br class=""><br class=""><br class=""><blockquote type="cite" class="">Dear Flash-users,<br class=""><br class="">I have been running into a few errors while trying to run a basic StirTurb<br class="">problem. What I essentially did was that, from the original StirTurb<br class="">problem package, I only made a few noticeable changes to flash.par and<br class="">added "REQUIRES physics/Hydro/HydroMain/unsplit/Hydro_Unsplit" to the<br class="">Config file. Then I setup the problem using the command<br class=""><br class="">./setup âauto -3d StirTurb -nxb=64 -nyb=64 -nzb=64 +ug<br class=""><br class="">and it successfully compiled.<br class=""><br class="">Running it however it proving to be a problem for me. When I set gamma to<br class="">1.4, I get a successful run but when I set it to 1.000 (Hoping to achieve<br class="">isothermal conditions), I get an error that says:<br class=""><br class="">*DRIVER_ABORT: [hy_uhd_eigenParameters-A]: Zero or imaginary sound speed<br class="">has obtained! Please try other (more diffusive) slope limiter, flux,<br class="">order,<br class="">cfl, etc.*<br class=""><br class=""><br class="">Could you please help me decipher where I am going wrong?<br class=""><br class="">Thank in advance.<br class=""><br class="">Kezman<br class=""><br class=""><br class="">*Provided below is the flash.par information I am using;*<br class=""><br class=""># runtime parameters, nxb = nyb = nzb = 64<br class=""><br class="">256^3 grid, gamma = 1.000<br class=""><br class="">xmax = 1.<br class=""><br class="">xmin = 0.<br class=""><br class="">ymax = 1.<br class=""><br class="">ymin = 0.<br class=""><br class="">zmax = 1.<br class=""><br class="">zmin = 0.<br class=""><br class=""><br class="">basenm = "driventurb_3d_"<br class=""><br class="">restart = .false.<br class=""><br class=""><br class=""># file numbers - if you restart you have to change the<br class="">checkpointFileNumber<br class=""><br class="">checkpointFileNumber = 0<br class=""><br class="">plotFileNumber = 0<br class=""><br class="">particleFileNumber = 0<br class=""><br class=""><br class=""># set the time between dumps<br class=""><br class="">checkpointFileIntervalTime = 0.01<br class=""><br class="">plotFileIntervalTime = 0.<br class=""><br class="">particleFileIntervalTime = 0.25<br class=""><br class=""><br class=""># set the number of steps between dumps<br class=""><br class="">checkpointFileIntervalStep = 0<br class=""><br class="">plotFileIntervalStep = 0<br class=""><br class="">particleFileIntervalStep = 0<br class=""><br class=""><br class="">useParticles= .false.<br class=""><br class="">pt_numX = 5<br class=""><br class="">pt_numY = 5<br class=""><br class="">pt_numZ = 5<br class=""><br class="">pt_maxPerProc=1000<br class=""><br class="">plot_var_1 = "dens"<br class=""><br class="">plot_var_2 = "pres"<br class=""><br class="">plot_var_3 = "temp"<br class=""><br class="">plot_var_4 = "velx"<br class=""><br class="">plot_var_5 = "vely"<br class=""><br class="">plot_var_6 = "velz"<br class=""><br class=""><br class="">plot_grid_var_1 = "mvrt"<br class=""><br class=""><br class="">gamma = 1.000<br class=""><br class=""><br class="">cfl = 0.8<br class=""><br class="">nend = 10000<br class=""><br class="">tmax = 0.05 # was originally 20.0<br class=""><br class=""><br class="">xl_boundary_type = "periodic"<br class=""><br class="">xr_boundary_type = "periodic"<br class=""><br class="">yl_boundary_type = "periodic"<br class=""><br class="">yr_boundary_type = "periodic"<br class=""><br class="">zl_boundary_type = "periodic"<br class=""><br class="">zr_boundary_type = "periodic"<br class=""><br class="">st_stirmax = 18.8478<br class=""><br class="">st_stirmin = 6.2832<br class=""><br class="">st_energy = 0.1<br class=""><br class="">st_decay = 0.5<br class=""><br class="">st_freq = 1<br class=""><br class="">eintSwitch = 1.<br class=""><br class=""><br class="">dtinit = 1.e-5<br class=""><br class="">dtmin = 1.e-12 # This parameter must be << minimum timestep<br class=""><br class=""> # in order to avoid numerical instability<br class=""><br class=""><br class="">smallt = 1.e-15<br class=""><br class="">smalle = 1.e-10<br class=""><br class=""><br class=""># AMR refinement parameters<br class=""><br class="">#lrefine_max = 6<br class=""><br class="">#refine_var_1 = "dens"<br class=""><br class=""><br class="">#These parameters below are only necessary for the Uniform Grid<br class=""><br class=""><br class="">iProcs = 4 #num procs in i direction<br class=""><br class="">jProcs = 4 #num procs in j direction<br class=""><br class="">kProcs = 4<br class=""><br class=""><br class=""># When using UG, iProcs, jProcs and kProcs must be specified.<br class=""><br class=""># These are the processors along each of the dimensions<br class=""><br class=""><br class="">#FIXEDBLOCKSIZE mode ::<br class=""><br class=""># When using fixed blocksize, iGridSize etc are redundant in<br class=""><br class=""># runtime parameters. These quantities are calculated as<br class=""><br class=""># iGridSize = NXB*iprocs<br class=""><br class=""># jGridSize = NYB*jprocs<br class=""><br class=""># kGridSize = NZB*kprocs<br class=""><br class=""><br class="">#NONFIXEDBLOCKSIZE mode ::<br class=""><br class=""># iGridSize etc must be specified. They constitute the global<br class=""><br class=""># number of grid points in the physical domain without taking<br class=""><br class=""># the guard cell into account. The local blocksize is calculated<br class=""><br class=""># as iGridSize/iprocs etc.<br class=""><br class=""><br class="">## -------------------------------------------------------------##<br class=""><br class="">## SWITCHES SPECIFIC TO THE UNSPLIT HYDRO SOLVER ##<br class=""><br class=""># I. INTERPOLATION SCHEME:<br class=""><br class="">order = 3 # Interpolation order (first/second/third/fifth<br class="">order)<br class=""><br class="">slopeLimiter = "vanLeer" # Slope limiters (minmod, mc, vanLeer,<br class="">hybrid, limited)<br class=""><br class="">LimitedSlopeBeta= 1. # Slope parameter for the "limited" slope by Toro<br class=""><br class="">charLimiting = .true. # Characteristic limiting vs. Primitive limiting<br class=""><br class=""><br class="">use_avisc = .false. # use artificial viscosity (originally for PPM)<br class=""><br class="">#cvisc = 0.1 # coefficient for artificial viscosity<br class=""><br class="">use_flattening = .false. # use flattening (dissipative) (originally for<br class="">PPM)<br class=""><br class="">use_steepening = .false. # use contact steepening (originally for PPM)<br class=""><br class="">use_upwindTVD = .false. # use upwind biased TVD slope for PPM (need<br class="">nguard=6)<br class=""><br class="">use_hybridOrder = .true.<br class=""><br class=""><br class=""># Magnetic and Electric Fields:<br class=""><br class="">E_modificaton = .true.<br class=""><br class="">energyFix = .true.<br class=""><br class="">ForceHydroLimit = .false.<br class=""><br class="">prolMethod = "injection_prol"<br class=""><br class=""><br class=""><br class=""># II. RIEMANN SOLVERS:<br class=""><br class="">RiemannSolver = "Hybrid" # Roe, HLL, HLLC, LLF, Marquina<br class=""><br class="">entropy = .true. # Entropy fix for the Roe solver<br class=""><br class="">EOSforRiemann = .true. # Call EOS in Riemann flux calculations<br class=""><br class=""><br class=""># III. STRONG SHOCK HANDELING SCHEME:<br class=""><br class="">shockDetect = .true. # Shock Detect for numerical stability<br class=""><br class="">## -------------------------------------------------------------##<br class=""><br class="">## ---------------------------------------------------------------##<br class=""><br class="">## SWITCHES SPECIFIC TO THE SUPER-TIME-STEPPING (STS) ALGORITHM ##<br class=""><br class="">## NOTE: For details on using STS runtime parameters, please ##<br class=""><br class="">## refer to user's guide (Driver chapter). ##<br class=""><br class="">useSTS = .false.<br class=""><br class="">nstepTotalSTS = 5<br class=""><br class="">nuSTS = 0.2<br class=""><br class="">## ---------------------------------------------------------------##<br class=""><br class=""></blockquote><br class=""><br class=""></div></div></blockquote></div><br class=""></div></body></html>