Diffusion.cpp

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/*
 * This file is part of Vlasiator.
 * Copyright 2010-2016 Finnish Meteorological Institute
 *
 * For details of usage, see the COPYING file and read the "Rules of the Road"
 * at http://www.physics.helsinki.fi/vlasiator/
 *
 * This program 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
#include <cstdlib>
#include <iostream>
#include <iomanip>
#include <cmath>
 
#include "../../common.h"
#include "../../readparameters.h"
#include "../../backgroundfield/backgroundfield.h"
#include "../../backgroundfield/constantfield.hpp"
#include "../../object_wrapper.h"
#include "Diffusion.h"
 
using namespace std;
using namespace spatial_cell;
 
namespace projects {
   Diffusion::Diffusion(): Project() { }
   Diffusion::~Diffusion() { }
 
   bool Diffusion::initialize(void) {
      return Project::initialize();
   }
 
   void Diffusion::addParameters() {
      typedef Readparameters RP;
      RP::add("Diffusion.B0", "Background field value (T)", 1.0e-9);
 
      // Per-population parameters
      for(uint i=0; i< getObjectWrapper().particleSpecies.size(); i++) {
         const std::string& pop = getObjectWrapper().particleSpecies[i].name;
 
         RP::add(pop + "_Diffusion.rho", "Number density (m^-3)", 1.0e7);
         RP::add(pop + "_Diffusion.Temperature", "Temperature (K)", 2.0e6);
         RP::add(pop + "_Diffusion.Scale_x", "Scale length in x (m)", 100000.0);
         RP::add(pop + "_Diffusion.Scale_y", "Scale length in y (m)", 100000.0);
      }
   }
 
   void Diffusion::getParameters() {
      Project::getParameters();
 
      typedef Readparameters RP;
      RP::get("Diffusion.B0", this->B0);
 
      // Per-population parameters
      for(uint i=0; i< getObjectWrapper().particleSpecies.size(); i++) {
        const std::string& pop = getObjectWrapper().particleSpecies[i].name;
        DiffusionSpeciesParameters sP;
 
        RP::get(pop + "_Diffusion.rho", sP.DENSITY);
        RP::get(pop + "_Diffusion.Temperature", sP.TEMPERATURE);
        RP::get(pop + "_Diffusion.Scale_x", sP.SCA_X);
        RP::get(pop + "_Diffusion.Scale_y", sP.SCA_Y);
 
        speciesParams.push_back(sP);
      }
   }
 
   Realf Diffusion::fillPhaseSpace(spatial_cell::SpatialCell *cell,
                                       const uint popID,
                                       const uint nRequested
      ) const {
      const DiffusionSpeciesParameters& sP = speciesParams[popID];
      creal mass = getObjectWrapper().particleSpecies[popID].mass;
      // Fetch spatial cell center coordinates
      const Real x  = cell->parameters[CellParams::XCRD] + 0.5*cell->parameters[CellParams::DX];
      const Real y  = cell->parameters[CellParams::YCRD] + 0.5*cell->parameters[CellParams::DY];
      const Real z  = cell->parameters[CellParams::ZCRD] + 0.5*cell->parameters[CellParams::DZ];
      const Real initV0X = 0;
      const Real initV0Y = 0;
      const Real initV0Z = 0;
      const Real kb = physicalconstants::K_B;
      const Real initRho = sP.DENSITY;
      const Real initT = sP.TEMPERATURE;
      const Real initScaY = sP.SCA_Y;
      const Real initScaX = sP.SCA_X;
 
      #ifdef USE_GPU
      vmesh::VelocityMesh *vmesh = cell->dev_get_velocity_mesh(popID);
      vmesh::VelocityBlockContainer* VBC = cell->dev_get_velocity_blocks(popID);
      #else
      vmesh::VelocityMesh *vmesh = cell->get_velocity_mesh(popID);
      vmesh::VelocityBlockContainer* VBC = cell->get_velocity_blocks(popID);
      #endif
      // Loop over blocks
      Realf rhosum = 0;
      arch::parallel_reduce<arch::null>(
         {WID, WID, WID, nRequested},
         ARCH_LOOP_LAMBDA (const uint i, const uint j, const uint k, const uint initIndex, Realf *lsum ) {
            vmesh::GlobalID *GIDlist = vmesh->getGrid()->data();
            Realf* bufferData = VBC->getData();
            const vmesh::GlobalID blockGID = GIDlist[initIndex];
            // Calculate parameters for new block
            Real blockCoords[6];
            vmesh->getBlockInfo(blockGID,&blockCoords[0]);
            creal vxBlock = blockCoords[0];
            creal vyBlock = blockCoords[1];
            creal vzBlock = blockCoords[2];
            creal dvxCell = blockCoords[3];
            creal dvyCell = blockCoords[4];
            creal dvzCell = blockCoords[5];
            ARCH_INNER_BODY(i, j, k, initIndex, lsum) {
               creal vx = vxBlock + (i+0.5)*dvxCell - initV0X;
               creal vy = vyBlock + (j+0.5)*dvyCell - initV0Y;
               creal vz = vzBlock + (k+0.5)*dvzCell - initV0Z;
               const Realf value = initRho * pow(mass / (2.0 * M_PI * kb * initT), 1.5) * (
                  5.0 * exp(- (pow(x, 2.0) / pow(initScaX, 2.0) +  pow(y, 2.0) / pow(initScaY, 2.0))) *
                  exp(- mass * (pow(vx, 2.0) + pow(vy, 2.0) + pow(vz, 2.0)) / (2.0 * kb * initT))
                  + exp(- mass * (pow(vx, 2.0) + pow(vy, 2.0) + pow(vz, 2.0)) / (2.0 * kb * initT)));
               bufferData[initIndex*WID3 + k*WID2 + j*WID + i] = value;
               //lsum[0] += value;
            };
         }, rhosum);
      return rhosum;
   }
 
   void Diffusion::calcCellParameters(spatial_cell::SpatialCell* cell,creal& t) { }
 
   void Diffusion::setProjectBField(
      fsgrids::perbspan perb,
      fsgrids::bgbspan bgb,
      fsgrids::technicalspan technical,
      FieldSolverGrid &fsgrid
   ) {
      ConstantField bgField;
      bgField.initialize(0,0,this->B0); //bg bx, by,bz
      setBackgroundField(bgField, bgb, technical, fsgrid);
   }
} // namespace projects