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joeri.brackenhoff authoredjoeri.brackenhoff authored
viscoelastic4.c 8.58 KiB
#include<stdlib.h>
#include<stdio.h>
#include<math.h>
#include<assert.h>
#include"fdelmodc.h"
#define MAX(x,y) ((x) > (y) ? (x) : (y))
int applySource(modPar mod, srcPar src, wavPar wav, bndPar bnd, int itime, int ixsrc, int izsrc, float *vx, float *vz, float *tzz,
float *txx, float *txz, float *rox, float *roz, float *l2m, float **src_nwav, int verbose);
int storeSourceOnSurface(modPar mod, srcPar src, bndPar bnd, int ixsrc, int izsrc, float *vx, float *vz, float *tzz, float *txx, float *txz, int verbose);
int reStoreSourceOnSurface(modPar mod, srcPar src, bndPar bnd, int ixsrc, int izsrc, float *vx, float *vz, float *tzz, float *txx, float *txz, int verbose);
int boundariesP(modPar mod, bndPar bnd, float *vx, float *vz, float *tzz, float *txx, float *txz, float *rox, float *roz, float *l2m, float *lam, float *mul, int itime, int verbose);
int boundariesV(modPar mod, bndPar bnd, float *vx, float *vz, float *tzz, float *txx, float *txz, float *rox, float *roz, float *l2m, float *lam, float *mul, int itime, int verbose);
int viscoelastic4(modPar mod, srcPar src, wavPar wav, bndPar bnd, int itime, int ixsrc, int izsrc, float **src_nwav, float *vx, float *vz, float *tzz, float *txx, float *txz, float *rox, float *roz, float *l2m, float *lam, float *mul, float *tss, float *tep, float *tes, float *r, float *q, float *p, int verbose)
{
/*********************************************************************
COMPUTATIONAL OVERVIEW OF THE 4th ORDER STAGGERED GRID:
The captial symbols T (=Txx,Tzz) Txz,Vx,Vz represent the actual grid
The indices ix,iz are related to the T grid, so the capital T
symbols represent the actual modelled grid.
one cel (iz,ix)
|
V extra column of vx,txz
|
------- V
| txz vz| txz vz txz vz txz vz txz vz txz vz txz
| |
| vx t | vx t vx t vx t vx t vx t vx
-------
txz vz txz vz txz vz txz vz txz vz txz vz txz
vx t vx T---Vx--T---Vx--T---Vx--T vx t vx
| | | | | | |
txz vz txz Vz--Txz-Vz--Txz-Vz Txz-Vz txz vz txz
| | | | | | |
vx t vx T---Vx--T---Vx--T---Vx--T vx t vx
| | | | | | |
txz vz txz Vz Txz-Vz Txz-Vz Txz-Vz txz vz txz
| | | | | | |
vx t vx T---Vx--T---Vx--T---Vx--T vx t vx
| | | | | | |
txz vz txz Vz Txz-Vz Txz-Vz Txz-Vz txz vz txz
| | | | | | |
vx t vx T---Vx--T---Vx--T---Vx--T vx t vx
txz vz txz vz txz vz txz vz txz vz txz vz txz
vx t vx t vx t vx t vx t vx t vx
txz vz txz vz txz vz txz vz txz vz txz vz txz <--|
|
extra row of txz/vz |
Implementation as described in:
Viscoelastic finite-difference modeling
Johan 0. A. Robertsson, Joakim 0. Blanch, and William W. Symes
GEOPHYSICS, VOL. 59, NO. 9 (SEPTEMBER 1994); P. 1444-1456
AUTHOR:
Jan Thorbecke (janth@xs4all.nl)
The Netherlands
***********************************************************************/
float c1, c2;
float ddt;
float *dxvx, *dzvz, *dxvz, *dzvx;
float *Tpp, *Tss, *Tmu, *Tlm, *Tlp, *Tus, *Tt1, *Tt2;
int ix, iz;
int n1;
// int ioXx, ioXz, ioZz, ioZx, ioPx, ioPz, ioTx, ioTz;
c1 = 9.0/8.0;
c2 = -1.0/24.0;
n1 = mod.naz;
ddt = 1.0/mod.dt;
dxvx = (float *)malloc(n1*sizeof(float));
dzvz = (float *)malloc(n1*sizeof(float));
dxvz = (float *)malloc(n1*sizeof(float));
dzvx = (float *)malloc(n1*sizeof(float));
Tpp = (float *)malloc(n1*sizeof(float));
Tss = (float *)malloc(n1*sizeof(float));
Tmu = (float *)malloc(n1*sizeof(float));
Tlm = (float *)malloc(n1*sizeof(float));
Tlp = (float *)malloc(n1*sizeof(float));
Tus = (float *)malloc(n1*sizeof(float));
Tt1 = (float *)malloc(n1*sizeof(float));
Tt2 = (float *)malloc(n1*sizeof(float));
/* Vx: rox */
// ioXx=mod.iorder/2;
// ioXz=ioXx-1;
/* Vz: roz */
// ioZz=mod.iorder/2;
// ioZx=ioZz-1;
/* P, Txx, Tzz: lam, l2m */
// ioPx=mod.iorder/2-1;
// ioPz=ioPx;
/* Txz: muu */
// ioTx=mod.iorder/2;
// ioTz=ioTx;
/* calculate vx for all grid points except on the virtual boundary*/
#pragma omp for private (ix, iz) nowait schedule(guided,1)
for (ix=mod.ioXx; ix<mod.ieXx; ix++) {
#pragma ivdep
for (iz=mod.ioXz; iz<mod.ieXz; iz++) {
vx[ix*n1+iz] -= rox[ix*n1+iz]*(
c1*(txx[ix*n1+iz] - txx[(ix-1)*n1+iz] +
txz[ix*n1+iz+1] - txz[ix*n1+iz]) +
c2*(txx[(ix+1)*n1+iz] - txx[(ix-2)*n1+iz] +
txz[ix*n1+iz+2] - txz[ix*n1+iz-1]) );
}
}
/* calculate vz for all grid points except on the virtual boundary */
#pragma omp for private (ix, iz) schedule(guided,1)
for (ix=mod.ioZx; ix<mod.ieZx; ix++) {
#pragma ivdep
for (iz=mod.ioZz; iz<mod.ieZz; iz++) {
vz[ix*n1+iz] -= roz[ix*n1+iz]*(
c1*(tzz[ix*n1+iz] - tzz[ix*n1+iz-1] +
txz[(ix+1)*n1+iz] - txz[ix*n1+iz]) +
c2*(tzz[ix*n1+iz+1] - tzz[ix*n1+iz-2] +
txz[(ix+2)*n1+iz] - txz[(ix-1)*n1+iz]) );
}
}
/* Add force source */ if (src.type > 5) {
applySource(mod, src, wav, bnd, itime, ixsrc, izsrc, vx, vz, tzz, txx, txz, rox, roz, l2m, src_nwav, verbose);
}
/* boundary condition clears velocities on boundaries */
boundariesP(mod, bnd, vx, vz, tzz, txx, txz, rox, roz, l2m, lam, mul, itime, verbose);
/* calculate Txx/Tzz for all grid points except on the virtual boundary */
#pragma omp for private (ix, iz) nowait schedule(guided,1)
for (ix=mod.ioPx; ix<mod.iePx; ix++) {
#pragma ivdep
for (iz=mod.ioPz; iz<mod.iePz; iz++) {
dxvx[iz] = c1*(vx[(ix+1)*n1+iz] - vx[ix*n1+iz]) +
c2*(vx[(ix+2)*n1+iz] - vx[(ix-1)*n1+iz]);
}
#pragma ivdep
for (iz=mod.ioPz; iz<mod.iePz; iz++) {
dzvz[iz] = c1*(vz[ix*n1+iz+1] - vz[ix*n1+iz]) +
c2*(vz[ix*n1+iz+2] - vz[ix*n1+iz-1]);
}
/* help variables to let the compiler vectorize the loops */
#pragma ivdep
for (iz=mod.ioPz; iz<mod.iePz; iz++) {
Tpp[iz] = tep[ix*n1+iz]*tss[ix*n1+iz];
Tss[iz] = tes[ix*n1+iz]*tss[ix*n1+iz];
Tmu[iz] = (1.0-Tss[iz])*tss[ix*n1+iz]*mul[ix*n1+iz];
Tlm[iz] = (1.0-Tpp[iz])*tss[ix*n1+iz]*l2m[ix*n1+iz]*0.5;
Tlp[iz] = l2m[ix*n1+iz]*Tpp[iz];
Tus[iz] = mul[ix*n1+iz]*Tss[iz];
}
#pragma ivdep
for (iz=mod.ioPz; iz<mod.iePz; iz++) {
Tt1[iz] = 1.0/(ddt+0.5*tss[ix*n1+iz]);
Tt2[iz] = ddt-0.5*tss[ix*n1+iz];
}
/* the update with the relaxation correction */
#pragma ivdep
for (iz=mod.ioPz; iz<mod.iePz; iz++) {
txx[ix*n1+iz] -= Tlp[iz]*dxvx[iz] + (Tlp[iz]-2.0*Tus[iz])*dzvz[iz] + q[ix*n1+iz];
tzz[ix*n1+iz] -= Tlp[iz]*dzvz[iz] + (Tlp[iz]-2.0*Tus[iz])*dxvx[iz] + p[ix*n1+iz];
}
#pragma ivdep
for (iz=mod.ioPz; iz<mod.iePz; iz++) {
q[ix*n1+iz] = (Tt2[iz]*q[ix*n1+iz] - Tmu[iz]*dzvz[iz] + Tlm[iz]*(dxvx[iz]+dzvz[iz]))*Tt1[iz];
txx[ix*n1+iz] -= q[ix*n1+iz];
}
#pragma ivdep
for (iz=mod.ioPz; iz<mod.iePz; iz++) {
p[ix*n1+iz] = (Tt2[iz]*p[ix*n1+iz] - Tmu[iz]*dxvx[iz] + Tlm[iz]*(dxvx[iz]+dzvz[iz]))*Tt1[iz];
tzz[ix*n1+iz] -= p[ix*n1+iz];
}
/* calculate Txz for all grid points except on the virtual boundary */
if (ix >= mod.ioTx) {
#pragma ivdep
for (iz=mod.ioTz; iz<mod.ieTz; iz++) {
dzvx[iz] = c1*(vx[ix*n1+iz] - vx[ix*n1+iz-1]) +
c2*(vx[ix*n1+iz+1] - vx[ix*n1+iz-2]);
}
#pragma ivdep
for (iz=mod.ioTz; iz<mod.ieTz; iz++) {
dxvz[iz] = c1*(vz[ix*n1+iz] - vz[(ix-1)*n1+iz]) +
c2*(vz[(ix+1)*n1+iz] - vz[(ix-2)*n1+iz]);
}
#pragma ivdep
for (iz=mod.ioTz; iz<mod.ieTz; iz++) {
txz[ix*n1+iz] -= Tus[iz]*(dzvx[iz]+dxvz[iz]) + r[ix*n1+iz];
r[ix*n1+iz] = (Tt2[iz]*r[ix*n1+iz] + 0.5*Tmu[iz]*(dzvx[iz]+dxvz[iz]))*Tt1[iz];
txz[ix*n1+iz] -= r[ix*n1+iz]; }
}
}
/* Add stress source */
if (src.type < 6) {
applySource(mod, src, wav, bnd, itime, ixsrc, izsrc, vx, vz, tzz, txx, txz, rox, roz, l2m, src_nwav, verbose);
}
/* check if there are sources placed on the free surface */
storeSourceOnSurface(mod, src, bnd, ixsrc, izsrc, vx, vz, tzz, txx, txz, verbose);
/* Free surface: calculate free surface conditions for stresses */
boundariesV(mod, bnd, vx, vz, tzz, txx, txz, rox, roz, l2m, lam, mul, itime, verbose);
/* restore source positions on the edge */
reStoreSourceOnSurface(mod, src, bnd, ixsrc, izsrc, vx, vz, tzz, txx, txz, verbose);
free(dxvx);
free(dzvz);
free(dzvx);
free(dxvz);
free(Tpp);
free(Tss);
free(Tmu);
free(Tlm);
free(Tlp);
free(Tus);
free(Tt1);
free(Tt2);
return 0;
}