CylindricalLBVelocityProfile.cpp

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/*
 * Copyright (C) 2016-2022 The ESPResSo project
 *
 * This file is part of ESPResSo.
 *
 * ESPResSo is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * ESPResSo is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "CylindricalLBVelocityProfile.hpp"
 
#include "system/System.hpp"
#include "utils_histogram.hpp"
 
#include <utils/Histogram.hpp>
#include <utils/math/coordinate_transformation.hpp>
 
#include <vector>
 
namespace Observables {
 
std::vector<double> CylindricalLBVelocityProfile::operator()(
    boost::mpi::communicator const &comm) const {
  using vel_type = Utils::Vector3d;
 
  decltype(sampling_positions) local_positions{};
  std::vector<vel_type> local_velocities{};
 
  auto const &lb = System::get_system().lb;
  auto const vel_conv = lb.get_lattice_speed();
 
  for (auto const &pos : sampling_positions) {
    if (auto const vel = lb.get_interpolated_velocity(pos)) {
      auto const pos_shifted = pos - transform_params->center();
      auto const pos_cyl = Utils::transform_coordinate_cartesian_to_cylinder(
          pos_shifted, transform_params->axis(),
          transform_params->orientation());
      auto const vel_cyl = Utils::transform_vector_cartesian_to_cylinder(
          (*vel) * vel_conv, transform_params->axis(), pos_shifted);
 
      local_positions.emplace_back(pos_cyl);
      local_velocities.emplace_back(vel_cyl);
    }
  }
 
  auto const [global_positions, global_velocities] =
      detail::gather(comm, local_positions, local_velocities);
 
  if (comm.rank() != 0) {
    return {};
  }
 
  Utils::CylindricalHistogram<double, 3> histogram(n_bins(), limits());
  detail::accumulate(histogram, global_positions, global_velocities);
  return detail::normalize_by_bin_size(histogram);
}
 
} // namespace Observables