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compute_temperature.cc
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Sat, Nov 9, 06:05

compute_temperature.cc
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#include "compute_temperature.hh"
#include "fft.hh"
#include "material_point.hh"
#include <cmath>
/* -------------------------------------------------------------------------- */
void ComputeTemperature::setDeltaT(Real dt) {
this->dt = dt;
}
void ComputeTemperature::compute(System& system) {
UInt size = system.getNbParticles();
UInt N = std::sqrt(size);
//////// VALUES TO BE SPECIFIED BY USER ////////////////////
Real L = 2.0;
Real dx = 0.2; // can also be extracted from distance between particle positions
Real rho = 1.0;
Real C = 1.0;
Real kappa = 1.0;
///////////////////////////////////////////////////////////
Real T = N*dx;
// We have "size" particles aligned on a "sqrt(size) x sqrt(size)" grid
Matrix<complex> theta(N);
Matrix<complex> hv(N);
//UInt k = 0;
UInt i, j;
for (auto& par : system) {
MaterialPoint & m_par = dynamic_cast<MaterialPoint&>(par);
Vector pos = m_par.getPosition();
Real x = pos[0];
Real y = pos[1];
i = round(((x + L/2.0) / dx));
j = round(((y + L/2.0) / dx));
// Get 2d index from 1D index: k = i + j * N
//j = N / k;
//i = k % N;
// Fill the matrix entry (corresponding to the particle par) with its temperature and heat rate
theta(i,j) = m_par.getTemperature();
hv(i,j) = m_par.getHeatRate();
//theta(i,j) = 1.0;
//hv(i,j) = 1.0;
// update 1D index
//k++;
} // end for loop over particles
std::cout << "We looped over this number of particles: " << std::endl;
Matrix<complex> theta_hat = FFT::transform(theta);
Matrix<std::complex<int>> q_squared = FFT::computeFrequencies(N);
/////// Temporary solution by converting from complex-int to complex-double
Matrix<std::complex<double>> q_squared_converted(N);
for (auto&& entry : index(q_squared_converted)) {
int i = std::get<0>(entry);
int j = std::get<1>(entry);
std::complex<double> in = ( std::real(q_squared(i,j)), std::imag(q_squared(i,j)) );
auto& out = std::get<2>(entry);
out = in;
}
//////////////////////////////////////////////////////////////////////////////
Matrix<complex> d_theta_hat_dt(N);
for (auto&& entry : index(d_theta_hat_dt)) {
int i = std::get<0>(entry);
int j = std::get<1>(entry);
auto& val = std::get<2>(entry);
val = ( 1 / (rho * C) ) * ( hv(i,j) - kappa * theta_hat(i,j) * (2*M_PI/T)*(2*M_PI/T) * q_squared_converted(i,j) );
}
Matrix<complex> d_theta_dt = FFT::itransform(d_theta_hat_dt);
for (auto&& entry : index(theta)) {
int i = std::get<0>(entry);
int j = std::get<1>(entry);
auto& val = std::get<2>(entry);
val += dt * d_theta_dt(i,j);
}
for (auto& par : system) {
MaterialPoint & m_par = dynamic_cast<MaterialPoint&>(par);
Vector pos = m_par.getPosition();
Real x = pos[0];
Real y = pos[1];
i = round(((x + L/2.0) / dx));
j = round(((y + L/2.0) / dx));
m_par.getTemperature() = std::real(theta(i,j));
} // end for loop over particles
}
/* -------------------------------------------------------------------------- */

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