//Basic first order semi-Lagrangian advection of velocities
void FluidSim::advect(float dt) {
temp_u.assign(0);
temp_v.assign(0);
temp_w.assign(0);
//semi-Lagrangian advection on u-component of velocity
for(int k = 0; k < nk; ++k) for(int j = 0; j < nj; ++j) for(int i = 0; i < ni+1; ++i) {
Vec3f pos(i*dx, (j+0.5f)*dx, (k+0.5f)*dx);
pos = trace_rk2(pos, -dt);
temp_u(i,j,k) = get_velocity(pos)[0];
}
//semi-Lagrangian advection on v-component of velocity
for(int k = 0; k < nk; ++k) for(int j = 0; j < nj+1; ++j) for(int i = 0; i < ni; ++i) {
Vec3f pos((i+0.5f)*dx, j*dx, (k+0.5f)*dx);
pos = trace_rk2(pos, -dt);
temp_v(i,j,k) = get_velocity(pos)[1];
}
//semi-Lagrangian advection on w-component of velocity
for(int k = 0; k < nk+1; ++k) for(int j = 0; j < nj; ++j) for(int i = 0; i < ni; ++i) {
Vec3f pos((i+0.5f)*dx, (j+0.5f)*dx, k*dx);
pos = trace_rk2(pos, -dt);
temp_w(i,j,k) = get_velocity(pos)[2];
}
//move update velocities into u/v vectors
u = temp_u;
v = temp_v;
w = temp_w;
}
//For extrapolated points, replace the normal component
//of velocity with the object velocity (in this case zero).
void FluidSim::constrain_velocity() {
temp_u = u;
temp_v = v;
//(At lower grid resolutions, the normal estimate from the signed
//distance function is poor, so it doesn't work quite as well.
//An exact normal would do better.)
//constrain u
for(int j = 0; j < u.nj; ++j) for(int i = 0; i < u.ni; ++i) {
if(u_weights(i,j) == 0) {
//apply constraint
Vec2f pos(i*dx, (j+0.5f)*dx);
Vec2f vel = get_velocity(pos);
Vec2f normal(0,0);
interpolate_gradient(normal, pos/dx, nodal_solid_phi);
normalize(normal);
float perp_component = dot(vel, normal);
vel -= perp_component*normal;
temp_u(i,j) = vel[0];
}
}
//constrain v
for(int j = 0; j < v.nj; ++j) for(int i = 0; i < v.ni; ++i) {
if(v_weights(i,j) == 0) {
//apply constraint
Vec2f pos((i+0.5f)*dx, j*dx);
Vec2f vel = get_velocity(pos);
Vec2f normal(0,0);
interpolate_gradient(normal, pos/dx, nodal_solid_phi);
normalize(normal);
float perp_component = dot(vel, normal);
vel -= perp_component*normal;
temp_v(i,j) = vel[1];
}
}
//update
u = temp_u;
v = temp_v;
}
//Basic first order semi-Lagrangian advection of velocities
void FluidSim::advect(float dt) {
//semi-Lagrangian advection on u-component of velocity
for(int j = 0; j < nj; ++j) for(int i = 0; i < ni+1; ++i) {
Vec2f pos(i*dx, (j+0.5f)*dx);
pos = trace_rk2(pos, -dt);
temp_u(i,j) = get_velocity(pos)[0];
}
//semi-Lagrangian advection on v-component of velocity
for(int j = 0; j < nj+1; ++j) for(int i = 0; i < ni; ++i) {
Vec2f pos((i+0.5f)*dx, j*dx);
pos = trace_rk2(pos, -dt);
temp_v(i,j) = get_velocity(pos)[1];
}
//move update velocities into u/v vectors
u = temp_u;
v = temp_v;
}
//---------------------------------------------------------------------------
//读取位移解及等效应变能数据
void Postprocessor::read_u_solution_equivalent_energy(const string &output_file_name, double equivalent_energy[])
{
//-------------------------------------------------------------------------------------------------
//二进制读取数据
int us, uis;
fstream idata(output_file_name.c_str(), ios::in|ios::binary);
//读取位移解数据
idata.read((char *)&us, sizeof(int));
idata.read((char *)&uis, sizeof(int));
vector<double> temp_u(uis);
u.assign(us, temp_u);
for(int i=0; i<us; i++)
for(int j=0; j<uis; j++)
idata.read((char *)&u[i][j], sizeof(double));
//读取等效应变能数据
idata.read((char *)equivalent_energy, sizeof(double)*9);
idata.close();
}
//For extrapolated points, replace the normal component
//of velocity with the object velocity (in this case zero).
void FluidSim::constrain_velocity() {
temp_u = u;
temp_v = v;
temp_w = w;
//(At lower grid resolutions, the normal estimate from the signed
//distance function can be poor, so it doesn't work quite as well.
//An exact normal would do better if we had it for the geometry.)
//constrain u
for(int k = 0; k < u.nk;++k) for(int j = 0; j < u.nj; ++j) for(int i = 0; i < u.ni; ++i) {
if(u_weights(i,j,k) == 0) {
//apply constraint
temp_u(i,j,k) = 0;//vel[0];
}
}
//constrain v
for(int k = 0; k < v.nk;++k) for(int j = 0; j < v.nj; ++j) for(int i = 0; i < v.ni; ++i) {
if(v_weights(i,j,k) == 0) {
//apply constraint
temp_v(i,j,k) = 0; //vel[1];
}
}
//constrain w
for(int k = 0; k < w.nk;++k) for(int j = 0; j < w.nj; ++j) for(int i = 0; i < w.ni; ++i) {
if(w_weights(i,j,k) == 0) {
//apply constraint
temp_w(i,j,k) = 0; //vel[2];
}
}
//update
u = temp_u;
v = temp_v;
w = temp_w;
}
