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danieljprice
impossibly slow simulations during hyperbolic star collisions
Dear users
I wanted to try the new feature to try hyperbolic star collisions like in Starsmasher. However, there are issues: the simulations are impossibly slow, and I hope for my errors.
I attach both the setup and the sim parameters:
# input file for binary setup routines
# units
mass_unit = solarm ! mass unit (e.g. solarm,jupiterm,1e6*solarm)
dist_unit = au ! distance unit (e.g. au,pc,kpc,0.1pc)
# options for star 1
iprofile1 = 2 ! 0=Sink,1=Unif,2=Poly,3=Dens,4=KEPL,5=MESA,6=Pie
Mstar1 = 1.000 ! mass of star 1 [Msun]
Rstar1 = 1.000 ! radius of star1 [Rsun]
np1 = 100000 ! number of particles
# options for star 2
iprofile2 = 2 ! 0=Sink,1=Unif,2=Poly,3=Dens,4=KEPL,5=MESA,6=Pie
Mstar2 = 0.56 ! mass of star 2 [Msun]
Rstar2 = 0.50 ! radius of star2 [Rsun]
# orbit settings
a = -0.117 ! semi-major axis (e.g. 1 au) or period (e.g. 10*days)
ecc = 1.020 ! eccentricity
inc = 90. ! inclination (deg)
O = 90. ! position angle of ascending node (deg)
w = 180. ! argument of periapsis (deg)
f = -160. ! initial true anomaly (180=apoastron)
corotate = F ! set stars in corotation
# relaxation options
relax = T ! relax stars into equilibrium
tol_ekin = 1.000E-07 ! tolerance on ekin/epot to stop relaxation
tol_dens = 1.000 ! % error in density to stop relaxation
maxits = 1000 ! maximum number of relaxation iterations
the sym parameters:
# Runtime options file for Phantom, written 25/02/2024 19:17:22.4
# Options not present assume their default values
# This file is updated automatically after a full dump
# job name
logfile = mysim01.log ! file to which output is directed
dumpfile = mysim_00000 ! dump file to start from
# options controlling run time and input/output
tmax = 10. ! end time
dtmax = 1.000 ! time between dumps
nmax = -1 ! maximum number of timesteps (0=just get derivs and stop)
nout = -1 ! write dumpfile every n dtmax (-ve=ignore)
nmaxdumps = -1 ! stop after n full dumps (-ve=ignore)
twallmax = 000:00 ! maximum wall time (hhh:mm, 000:00=ignore)
dtwallmax = 024:00 ! maximum wall time between dumps (hhh:mm, 000:00=ignore)
nfulldump = 10 ! full dump every n dumps
iverbose = 0 ! verboseness of log (-1=quiet 0=default 1=allsteps 2=debug 5=max)
# options controlling accuracy
C_cour = 0.300 ! Courant number
C_force = 0.250 ! dt_force number
tolv = 1.000E-02 ! tolerance on v iterations in timestepping
hfact = 1.200 ! h in units of particle spacing [h = hfact(m/rho)^(1/3)]
tolh = 1.000E-04 ! tolerance on h-rho iterations
tree_accuracy = 0.500 ! tree opening criterion (0.0-1.0)
# options controlling hydrodynamics, shock capturing
alpha = 0.000 ! MINIMUM shock viscosity parameter
alphamax = 1.000 ! MAXIMUM shock viscosity parameter
alphau = 1.000 ! shock conductivity parameter
beta = 2.000 ! beta viscosity
avdecayconst = 0.100 ! decay time constant for viscosity switches
# options controlling damping
idamp = 0 ! artificial damping of velocities (0=off, 1=constant, 2=star, 3=disc)
# options controlling equation of state
ieos = 2 ! eqn of state (1=isoth;2=adiab;3=locally iso;8=barotropic)
mu = 2.381 ! mean molecular weight
ipdv_heating = 1 ! heating from PdV work (0=off, 1=on)
ishock_heating = 1 ! shock heating (0=off, 1=on)
# options controlling cooling
C_cool = 0.050 ! factor controlling cooling timestep
icooling = 0 ! cooling function (0=off, 1=cooling library (step), 2=cooling library (force),3=Gammie, 5,6=KI02, 7=powerlaw)
# options controlling sink particles
icreate_sinks = 0 ! allow automatic sink particle creation
h_soft_sinksink = 0.000 ! softening length between sink particles
f_acc = 0.800 ! particles < f_acc*h_acc accreted without checks
r_merge_uncond = 0.000 ! sinks will unconditionally merge within this separation
r_merge_cond = 0.000 ! sinks will merge if bound within this radius
# options relating to external forces
iexternalforce = 0 ! 1=star,2=coro,3=bina,4=prdr,5=toru,6=toys,7=exte,8=spir,9=Lens,10=dens,11=Eins,
# options controlling physical viscosity
irealvisc = 0 ! physical viscosity type (0=none,1=const,2=Shakura/Sunyaev)
shearparam = 0.100 ! magnitude of shear viscosity (irealvisc=1) or alpha_SS (irealvisc=2)
bulkvisc = 0.000 ! magnitude of bulk viscosity
# options for injecting/removing particles
rkill = -1.000 ! deactivate particles outside this radius (<0 is off)
# gravitational waves
gw = F ! calculate gravitational wave strain
The simulation works at full power on Apple Silicon (M1Pro), and it's impossibly slow:
t = 0.45005E-05 dt = 4.529E-06 (courant), np = 156000
t = 0.90291E-05 dt = 4.557E-06 (courant)
t = 0.13586E-04 dt = 4.585E-06 (courant)
t = 0.18170E-04 dt = 4.612E-06 (courant)
t = 0.22783E-04 dt = 4.640E-06 (courant)
t = 0.27423E-04 dt = 4.668E-06 (courant)
t = 0.32091E-04 dt = 4.694E-06 (courant)
t = 0.36786E-04 dt = 4.721E-06 (courant)
t = 0.41507E-04 dt = 4.748E-06 (courant)
t = 0.46255E-04 dt = 4.775E-06 (courant)
t = 0.51030E-04 dt = 4.801E-06 (courant)
t = 0.55831E-04 dt = 4.828E-06 (courant)
t = 0.60659E-04 dt = 4.855E-06 (courant)
t = 0.65514E-04 dt = 4.882E-06 (courant)
t = 0.70396E-04 dt = 4.908E-06 (courant)
Am I doing something wrong? I remember once (older version before the hyperbolic implementation) that i ran a binary example with eccentricity = 1 and the simulation was done in a matter of minutes with around 200k particles... Now it can't even run fast 2 identical stars with an eccentricity of 0.
Best
Francesco
the limitation of the setup you are using is that you have to set the true anomaly (f, in degrees) to specify the position of the star prior to the encounter. The value you have chosen probably puts the star close to -infinity. Would suggest you have a look at the distance between the two stars from your initial setup and adjust the value of f accordingly
The star is not closed to infinity, they are at a distance of 30 solar radius...
The problem is also present when I try to relax the star running the code. The repository that I'm using is some months old, tomorrow I will try the newest and let you know. In case, can you please try to run the code in your laptop? That situation is very weird :(
Thank you for the availability
Here i'm again... I installed the new version of the code and the problem is still present: the simulation is impossibly slow using both polytropes and MESA. I have no idea why, i'm sure that months ago my simulation was super fast..
I attach here the setup and the sim setup, am i doing something wrong?
As you can see here, one of the star is not close to infinity:
I have no idea where the problem is, maybe in the setup? I just followed the guide exporting:
SYSTEM = gfortran
export OMP_SCHEDULE="dynamic"
export OMP_STACKSIZE=512M
ulimit -s unlimited
@danieljprice can you please try to run this setup? I have no idea where the problem is:
# input file for binary setup routines
# units
mass_unit = solarm ! mass unit (e.g. solarm,jupiterm,1e6*solarm)
dist_unit = au ! distance unit (e.g. au,pc,kpc,0.1pc)
# options for star 1
iprofile1 = 2 ! 0=Sink,1=Unif,2=Poly,3=Dens,4=KEPL,5=MESA,6=Pie
Mstar1 = 1.000 ! mass of star 1 [Msun]
Rstar1 = 1.000 ! radius of star1 [Rsun]
np1 = 100000 ! number of particles
# options for star 2
iprofile2 = 2 ! 0=Sink,1=Unif,2=Poly,3=Dens,4=KEPL,5=MESA,6=Pie
Mstar2 = 0.55 ! mass of star 2 [Msun]
Rstar2 = 0.55 ! radius of star2 [Rsun]
# orbit settings
a = -0.720 ! semi-major axis (e.g. 1 au) or period (e.g. 10*days)
ecc = 1.030 ! eccentricity
inc = 0. ! inclination (deg)
O = 90. ! position angle of ascending node (deg)
w = 180. ! argument of periapsis (deg)
f = -100. ! initial true anomaly (180=apoastron)
corotate = F ! set stars in corotation
# relaxation options
relax = T ! relax stars into equilibrium
tol_ekin = 1.000E-07 ! tolerance on ekin/epot to stop relaxation
maxits = 1000 ! maximum number of relaxation iterations
Thank you for help and availability
Francesco