euler.cc (Latest change: Author:Lakshman Anumolu <acrlakshman@yahoo.co.in>, 2019-07-25 22:27:47 -0500, [commit: 74d2125])

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// Copyright 2019 Lakshman Anumolu, Raunak Bardia.
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#include "gals/cpu/temporal-schemes/semi-lagrangian/euler.h"
#include "gals/cpu/gradient.h"
#include "gals/cpu/interpolate.h"

#include <math.h>

template <typename T, typename T_GRID>
GALS::TEMPORAL_SCHEMES::SEMI_LAGRANGIAN::Euler<T, T_GRID>::Euler()
{
}

template <typename T, typename T_GRID>
GALS::TEMPORAL_SCHEMES::SEMI_LAGRANGIAN::Euler<T, T_GRID>::~Euler()
{
}

template <typename T, typename T_GRID>
void GALS::TEMPORAL_SCHEMES::SEMI_LAGRANGIAN::Euler<T, T_GRID>::compute(
    const T dt, const GALS::CPU::LevelsetVelocity<T_GRID, T> &levelset_velocity,
    GALS::CPU::Levelset<T_GRID, T> &levelset)
{
  const auto &grid = levelset.grid();
  const auto &velocity = levelset_velocity.velocity();
  const auto &velocity_grad = levelset_velocity.velocityGradient();
  const GALS::CPU::Vec3<int> num_cells = grid.numCells();
  auto &phi = levelset.phi();
  auto &psi = levelset.psi();

  // Compute x_root `root of the characteristic`.
  GALS::CPU::Array<T_GRID, GALS::CPU::Vec3<T>> x_root(grid);

  for (int i = 0; i < num_cells[0]; ++i)
    for (int j = 0; j < num_cells[1]; ++j)
      for (int k = 0; k < num_cells[2]; ++k) x_root(i, j, k) = grid(i, j, k) - velocity(i, j, k) * dt;

  // Compute phi_interp_prev, psi_interp_prev at x_root.
  GALS::CPU::Interpolate<T, T_GRID, GALS::INTERPOLATION::Hermite<T, T_GRID>>::compute(x_root, levelset);

  // Compute x_root_grad.
  GALS::CPU::Array<T_GRID, GALS::CPU::Mat3<T>> x_root_grad(grid);

  const auto &identity_mat = T_GRID::identity_mat;

  for (int i = 0; i < num_cells[0]; ++i)
    for (int j = 0; j < num_cells[1]; ++j)
      for (int k = 0; k < num_cells[2]; ++k) x_root_grad(i, j, k) = identity_mat - velocity_grad(i, j, k) * dt;

  const auto &phi_interp_prev = levelset.phiInterpPrev();
  const auto &psi_interp_prev = levelset.psiInterpPrev();

  // Update phi and psi.
  for (int i = 0; i < num_cells[0]; ++i)
    for (int j = 0; j < num_cells[1]; ++j)
      for (int k = 0; k < num_cells[2]; ++k) {
        phi(i, j, k) = phi_interp_prev(i, j, k);
        psi(i, j, k) = x_root_grad(i, j, k).dot(psi_interp_prev(i, j, k));
      }
}

template class GALS::TEMPORAL_SCHEMES::SEMI_LAGRANGIAN::Euler<double, GALS::CPU::Grid<double, 1>>;
template class GALS::TEMPORAL_SCHEMES::SEMI_LAGRANGIAN::Euler<double, GALS::CPU::Grid<double, 2>>;
template class GALS::TEMPORAL_SCHEMES::SEMI_LAGRANGIAN::Euler<double, GALS::CPU::Grid<double, 3>>;