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predict.c
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Mon, Jun 3, 01:07

predict.c
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <mpi.h>
#include <gsl/gsl_math.h>
#include "allvars.h"
#include "proto.h"
/*! \file predict.c
* \brief drift particles by a small time interval
*
* This function contains code to implement a drift operation on all the
* particles, which represents one part of the leapfrog integration scheme.
*/
/*! This function drifts all particles from the current time to the future:
* time0 - > time1
*
* If there is no explicit tree construction in the following timestep, the
* tree nodes are also drifted and updated accordingly. Note: For periodic
* boundary conditions, the mapping of coordinates onto the interval
* [0,All.BoxSize] is only done before the domain decomposition, or for
* outputs to snapshot files. This simplifies dynamic tree updates, and
* allows the domain decomposition to be carried out only every once in a
* while.
*/
void move_particles(int time0, int time1)
{
int i, j;
double dt_drift, dt_gravkick, dt_hydrokick, dt_entr;
double t0, t1;
t0 = second();
if(All.ComovingIntegrationOn)
{
dt_drift = get_drift_factor(time0, time1);
dt_gravkick = get_gravkick_factor(time0, time1);
dt_hydrokick = get_hydrokick_factor(time0, time1);
}
else
{
dt_drift = dt_gravkick = dt_hydrokick = (time1 - time0) * All.Timebase_interval;
}
for(i = 0; i < NumPart; i++)
{
for(j = 0; j < 3; j++)
P[i].Pos[j] += P[i].Vel[j] * dt_drift;
if(P[i].Type == 0)
{
#ifdef PMGRID
for(j = 0; j < 3; j++)
{
SphP[i].VelPred[j] += (P[i].GravAccel[j] + P[i].GravPM[j]) * dt_gravkick + SphP[i].HydroAccel[j] * dt_hydrokick;
}
#else
for(j = 0; j < 3; j++)
{
SphP[i].VelPred[j] += P[i].GravAccel[j] * dt_gravkick + SphP[i].HydroAccel[j] * dt_hydrokick;
}
#endif
SphP[i].Density *= exp(-SphP[i].DivVel * dt_drift);
SphP[i].Hsml *= exp(0.333333333333 * SphP[i].DivVel * dt_drift);
if(SphP[i].Hsml < All.MinGasHsml)
SphP[i].Hsml = All.MinGasHsml;
dt_entr = (time1 - (P[i].Ti_begstep + P[i].Ti_endstep) / 2) * All.Timebase_interval;
SphP[i].Pressure = (SphP[i].Entropy + SphP[i].DtEntropy * dt_entr) * pow(SphP[i].Density, GAMMA);
#ifdef ENTROPYPRED
SphP[i].EntropyPred = (SphP[i].Entropy + SphP[i].DtEntropy * dt_entr);
#endif
#ifdef CHECK_ENTROPY_SIGN
if ((SphP[i].EntropyPred < 0)||(SphP[i].Entropy < 0))
{
printf("\ntask=%d: entropy less than zero in move_particles !\n", ThisTask);
printf("ID=%d Entropy=%g EntropyPred=%g DtEntropy=%g dt_entr=%g\n",P[i].ID,SphP[i].Entropy,SphP[i].EntropyPred,SphP[i].DtEntropy,dt_entr);
fflush(stdout);
endrun(333021);
}
#endif
#ifdef NO_NEGATIVE_PRESSURE
if (SphP[i].Pressure<0)
{
printf("\ntask=%d: pressure less than zero in move_particles !\n", ThisTask);
printf("ID=%d Entropy=%g DtEntropy*dt=%g Density=%g DtEntropy=%g dt=%g\n",P[i].ID,SphP[i].Entropy,SphP[i].DtEntropy*dt_entr,SphP[i].Density,SphP[i].DtEntropy,dt_entr);
fflush(stdout);
endrun(333022);
}
#endif
/***********************************************************/
/* compute art visc coeff */
/***********************************************************/
#if defined(ART_VISCO_MM)|| defined(ART_VISCO_RO) || defined(ART_VISCO_CD)
move_art_visc(i,dt_drift);
#endif
}
}
/* if domain-decomp and tree are not going to be reconstructed, update dynamically. */
if(All.NumForcesSinceLastDomainDecomp < All.TotNumPart * All.TreeDomainUpdateFrequency)
{
for(i = 0; i < Numnodestree; i++)
for(j = 0; j < 3; j++)
Nodes[All.MaxPart + i].u.d.s[j] += Extnodes[All.MaxPart + i].vs[j] * dt_drift;
force_update_len();
force_update_pseudoparticles();
}
t1 = second();
All.CPU_Predict += timediff(t0, t1);
}
/*! This function makes sure that all particle coordinates (Pos) are
* periodically mapped onto the interval [0, BoxSize]. After this function
* has been called, a new domain decomposition should be done, which will
* also force a new tree construction.
*/
#ifdef PERIODIC
void do_box_wrapping(void)
{
int i, j;
double boxsize[3];
for(j = 0; j < 3; j++)
boxsize[j] = All.BoxSize;
#ifdef LONG_X
boxsize[0] *= LONG_X;
#endif
#ifdef LONG_Y
boxsize[1] *= LONG_Y;
#endif
#ifdef LONG_Z
boxsize[2] *= LONG_Z;
#endif
for(i = 0; i < NumPart; i++)
for(j = 0; j < 3; j++)
{
while(P[i].Pos[j] < 0)
P[i].Pos[j] += boxsize[j];
while(P[i].Pos[j] >= boxsize[j])
P[i].Pos[j] -= boxsize[j];
}
}
#endif

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