RE: Trouble running the same simulation with gas particles

From: Phil Sutton <P.J.Sutton_at_lboro.ac.uk>
Date: Tue, 20 Jan 2015 11:26:30 +0000

Hi Matthias,

Unfortunately I have this set to a rather large non-zero value. Would there be anything else in the parameter file that might throw up this error? Although I have tried to not have any zero values. I can only assume it something to do with hydrodynamical element of the time step performed by Gadget?

Thanks

Phil

-----Original Message-----
From: Matthias Kühtreiber [mailto:a0749244_at_unet.univie.ac.at]
Sent: 20 January 2015 10:52
To: Gadget General Discussion
Subject: Re: [gadget-list] Trouble running the same simulation with gas particles


Hi Phil,

Have you double-checked that the value of "SofteningGas" in your parameter file is set to a non-zero value?
A gravitational softening of 0 can lead to similar errors you described above.

Best wishes,

Matthias Kühtreiber
Department of Astrophysics
University of Vienna



On Di, 20.01.2015, 10:58, Phil Sutton wrote:
> Hi all,
>
> For a while now I have been running a few simulations successfully
> using non-gas particles. However, I now wish to include some gas
> particles and have run into some problems getting Gadget2 to initial
> run. I now have two initial conditions that creates a ring of
> particles around a larger central mass. The velocities all assume
> circular Keplerian motions with the following:
> [cid:image003.jpg_at_01D03497.9310C440]
>
> All particle number densities, velocities and masses are the same (I
> added in a new array for internal energies of gas particles). The only
> difference is the particle type. The non-gas IC runs fine with no
> errors and continues to evolve in a Keplerian way. However, when gas
> particles are used for the ring a zero time step is assigned. I have
> tried altering the smoothing lengths, mass, number of particles and
> scale of the system from ridiculously small and large with no effect.
> The only thing that allows Gadget2 to run is if I reduce the central
> mass down by a factor of 10, which obviously results in the ring
> particles no longer having Keplerian motions about the centre. I have
> probably made a simple error in setting up of the initial conditions
> or an assumptions I’ve made when using gas particles but am running
> out of ideas to try. Any help would be great.
>
> Here is the errors for the gas particle IC followed by the successful
> non-gas IC if it helps:
>
>
> This is Gadget, version `2.0'.
>
>
>
> Running on 12 processors.
>
>
>
> Allocated 30 MByte communication buffer per processor.
>
>
>
> Communication buffer has room for 604946 particles in gravity
> computation
>
> Communication buffer has room for 245760 particles in density
> computation
>
> Communication buffer has room for 196608 particles in hydro
> computation
>
> Communication buffer has room for 196608 particles in domain
> decomposition
>
>
>
>
>
> Hubble (internal units) = 3.24078e-18
>
> G (internal units) = 6.672e-08
>
> UnitMass_in_g = 1
>
> UnitTime_in_s = 1
>
> UnitVelocity_in_cm_per_s = 1
>
> UnitDensity_in_cgs = 1
>
> UnitEnergy_in_cgs = 1
>
>
>
>
>
> Allocated 0.567307 MByte for particle storage. 68
>
>
>
> Allocated 0.70079 MByte for storage of SPH data. 84
>
>
>
>
>
> reading file `gas.dat' on task=0 (contains 35000 particles.)
>
> distributing this file to tasks 0-11
>
> Type 0 (gas): 34999 (tot= 0000034999) masstab=0
>
> Type 1 (halo): 0 (tot= 0000000000) masstab=0
>
> Type 2 (disk): 1 (tot= 0000000001) masstab=0
>
> Type 3 (bulge): 0 (tot= 0000000000) masstab=0
>
> Type 4 (stars): 0 (tot= 0000000000) masstab=0
>
> Type 5 (bndry): 0 (tot= 0000000000) masstab=0
>
>
>
> reading done.
>
> Total number of particles : 0000035000
>
>
>
> allocated 0.0762939 Mbyte for ngb search.
>
>
>
> Allocated 1.63065 MByte for BH-tree. 64
>
>
>
> domain decomposition...
>
> NTopleaves= 1436
>
> work-load balance=1.01143 memory-balance=1.01143
>
> exchange of 0000032087 particles
>
> domain decomposition done.
>
> begin Peano-Hilbert order...
>
> Peano-Hilbert done.
>
> Begin Ngb-tree construction.
>
> Ngb-Tree contruction finished
>
> ngb iteration 1: need to repeat for 0000034999 particles.
>
> ngb iteration 2: need to repeat for 0000034999 particles.
>
> ngb iteration 3: need to repeat for 0000034967 particles.
>
> ngb iteration 4: need to repeat for 0000034163 particles.
>
> ngb iteration 5: need to repeat for 0000027944 particles.
>
> ngb iteration 6: need to repeat for 0000014669 particles.
>
> ngb iteration 7: need to repeat for 0000004986 particles.
>
> ngb iteration 8: need to repeat for 0000001284 particles.
>
> ngb iteration 9: need to repeat for 0000000446 particles.
>
> ngb iteration 10: need to repeat for 0000000211 particles.
>
> ngb iteration 11: need to repeat for 0000000088 particles.
>
> ngb iteration 12: need to repeat for 0000000026 particles.
>
> ngb iteration 13: need to repeat for 0000000005 particles.
>
>
>
> Setting next time for snapshot file to Time_next= 0
>
>
>
>
>
> writing snapshot file...
>
> done with snapshot.
>
>
>
> Setting next time for snapshot file to Time_next= 500
>
>
>
>
>
> Begin Step 0, Time: 0, Systemstep: 0
>
> domain decomposition...
>
> NTopleaves= 1436
>
> work-load balance=1.01143 memory-balance=1.01143
>
> domain decomposition done.
>
> begin Peano-Hilbert order...
>
> Peano-Hilbert done.
>
> Start force computation...
>
> Tree construction.
>
> Tree construction done.
>
> Begin tree force.
>
> tree is done.
>
> Begin tree force.
>
> tree is done.
>
> Start density computation...
>
> Start hydro-force computation...
>
> force computation done.
>
>
>
> Error: A timestep of size zero was assigned on the integer timeline!
>
> We better stop.
>
> Task=0 Part-ID=0 dt=-nan tibase=3.72529e-05 ti_step=-2147483648
> ac=-nan
> xyz=(2.05361e+11|-1.32362e+09|0) tree=(-0.999847|0.006444340)
>
>
>
> hydro-frc=(-nan|-nan|-nan)
>
> task 0: endrun called with an error level of 818
>
>
>
>
>
>
>
> Error: A timestep of size zero was assigned on the integer timeline!
>
> We better stop.
>
> Task=1 Part-ID=0 dt=-nan tibase=3.72529e-05 ti_step=-2147483648
> ac=-nan
> xyz=(1.40842e+11|-1.21532e+11|0) tree=(-0.922557|0.796070)
>
>
>
> hydro-frc=(-nan|-nan|-nan)
> task 1: endrun called with an error level of 818
>
>
>
>
> This is Gadget, version `2.0'.
>
>
>
> Running on 12 processors.
>
>
>
> Allocated 30 MByte communication buffer per processor.
>
>
>
> Communication buffer has room for 604946 particles in gravity
> computation
>
> Communication buffer has room for 245760 particles in density
> computation
>
> Communication buffer has room for 196608 particles in hydro
> computation
>
> Communication buffer has room for 196608 particles in domain
> decomposition
>
>
>
>
>
> Hubble (internal units) = 3.24078e-18
>
> G (internal units) = 6.672e-08
>
> UnitMass_in_g = 1
>
> UnitTime_in_s = 1
>
> UnitVelocity_in_cm_per_s = 1
>
> UnitDensity_in_cgs = 1
>
> UnitEnergy_in_cgs = 1
>
>
>
>
>
> Allocated 0.53112 MByte for particle storage. 68
>
>
>
>
>
> reading file `non_gas.dat' on task=0 (contains 32768 particles.)
>
> distributing this file to tasks 0-11
>
> Type 0 (gas): 0 (tot= 0000000000) masstab=0
>
> Type 1 (halo): 32767 (tot= 0000032767) masstab=0
>
> Type 2 (disk): 1 (tot= 0000000001) masstab=0
>
> Type 3 (bulge): 0 (tot= 0000000000) masstab=0
>
> Type 4 (stars): 0 (tot= 0000000000) masstab=0
>
> Type 5 (bndry): 0 (tot= 0000000000) masstab=0
>
>
>
> reading done.
>
> Total number of particles : 0000032768
>
>
>
> allocated 0.0762939 Mbyte for ngb search.
>
>
>
> Allocated 1.5753 MByte for BH-tree. 64
>
>
>
> domain decomposition...
>
> NTopleaves= 1450
>
> work-load balance=1.01807 memory-balance=1.01807
>
> exchange of 0000030112 particles
>
> domain decomposition done.
>
> begin Peano-Hilbert order...
>
> Peano-Hilbert done.
>
> Begin Ngb-tree construction.
>
> Ngb-Tree contruction finished
>
>
>
> Setting next time for snapshot file to Time_next= 0
>
>
>
>
>
> writing snapshot file...
>
> done with snapshot.
>
>
>
> Setting next time for snapshot file to Time_next= 500
>
>
>
>
>
> Begin Step 0, Time: 0, Systemstep: 0
>
> domain decomposition...
>
> NTopleaves= 1450
>
> work-load balance=1.01807 memory-balance=1.01807
>
> domain decomposition done.
>
> begin Peano-Hilbert order...
>
> Peano-Hilbert done.
>
> Start force computation...
>
> Tree construction.
>
> Tree construction done.
>
> Begin tree force.
>
> tree is done.
>
> Begin tree force.
>
> tree is done.
>
> force computation done.
>
>
>
> Begin Step 1, Time: 4.88281, Systemstep: 4.88281
>
> domain decomposition...
>
> NTopleaves= 1450
>
> work-load balance=1.02153 memory-balance=1.38647
>
> exchange of 0000004772 particles
>
> domain decomposition done.
>
> begin Peano-Hilbert order...
>
> Peano-Hilbert done.
>
> Start force computation...
>
> Tree construction.
>
> Tree construction done.
>
> Begin tree force.
>
> tree is done.
>
> force computation done.
>
>
>
> Begin Step 2, Time: 9.76562, Systemstep: 4.88281
>
> domain decomposition...
>
> NTopleaves= 1457
>
> work-load balance=1.03279 memory-balance=1.36597
>
> exchange of 0000000226 particles
>
> domain decomposition done.
>
> begin Peano-Hilbert order...
>
> Peano-Hilbert done.
>
> Start force computation...
>
> Tree construction.
>
> Tree construction done.
>
> Begin tree force.
>
> tree is done.
>
> force computation done.
>
> Regards
>
> Phil Sutton
> Physics Department
> Loughborough University
>
>




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Received on 2015-01-20 12:26:40

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