/**
* @brief Moves particles forward based on 2nd order Runge-Kutta method
*
* @param[in] endTime Final time of the simulation
**/
void Runge_Kutta2::moveParticles(const double endTime) {
while (currentTime < endTime) {
const double dt = modifyTimeStep(1.0e-4f, init_dt); // implement dynamic timstep (if necessary):
const doubleV vdt = set1_pd(dt); // store timestep as vector const
const cloud_index numParticles = cloud->n;
operate1(currentTime);
force1(currentTime); // compute net force1
BEGIN_PARALLEL_FOR(i, e, numParticles, DOUBLE_STRIDE, static) // calculate k1 and l1 for entire cloud
const doubleV vmass = load_pd(cloud->mass + i); // load ith and (i+1)th mass into vector
// assign force pointers for stylistic purposes:
double * const pFx = cloud->forceX + i;
double * const pFy = cloud->forceY + i;
store_pd(cloud->k1 + i, div_pd(mul_pd(vdt, load_pd(pFx)), vmass)); // velocityX tidbit
store_pd(cloud->l1 + i, mul_pd(vdt, cloud->getVx1_pd(i))); // positionX tidbit
store_pd(cloud->m1 + i, div_pd(mul_pd(vdt, load_pd(pFy)), vmass)); // velocityY tidbit
store_pd(cloud->n1 + i, mul_pd(vdt, cloud->getVy1_pd(i))); // positionY tidbit
// reset forces to zero:
store_pd(pFx, set0_pd());
store_pd(pFy, set0_pd());
END_PARALLEL_FOR
operate2(currentTime + dt/2.0);
force2(currentTime + dt/2.0); // compute net force2
BEGIN_PARALLEL_FOR(i, e, numParticles, DOUBLE_STRIDE, static) // calculate k2 and l for entire cloud
const doubleV vmass = load_pd(cloud->mass + i);
// assign force pointers:
double * const pFx = cloud->forceX + i;
double * const pFy = cloud->forceY + i;
store_pd(cloud->k2 + i, div_pd(mul_pd(vdt, load_pd(pFx)), vmass)); // velocityX tidbit
store_pd(cloud->l2 + i, mul_pd(vdt, cloud->getVx2_pd(i))); // positionX tidbit
store_pd(cloud->m2 + i, div_pd(mul_pd(vdt, load_pd(pFy)), vmass)); // velocityY tidbit
store_pd(cloud->n2 + i, mul_pd(vdt, cloud->getVy2_pd(i))); // positionY tidbit
// reset forces to zero:
store_pd(pFx, set0_pd());
store_pd(pFy, set0_pd());
END_PARALLEL_FOR
// Calculate next position and next velocity for entire cloud.
BEGIN_PARALLEL_FOR(i, e, numParticles, DOUBLE_STRIDE, static)
plusEqual_pd(cloud->Vx + i, load_pd(cloud->k2 + i));
plusEqual_pd(cloud->x + i, load_pd(cloud->l2 + i));
plusEqual_pd(cloud->Vy + i, load_pd(cloud->m2 + i));
plusEqual_pd(cloud->y + i, load_pd(cloud->n2 + i));
END_PARALLEL_FOR
currentTime += dt;
}
}
//------------------------------------------------------------------------------
PD_Particles load_pd(string loadPath, unordered_map<string, double> particleParameters)
{
PD_Particles particles = load_pd(loadPath);
if(!particleParameters.empty())
{
for(auto pm:particleParameters)
{
particles.registerParameter(pm.first, pm.second);
}
}
return particles;
}
