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#include <iostream>
#include "lbm.h"
#include "boundary_conditions.h"
constexpr std::size_t dimX = 100;
constexpr std::size_t dimY = dimX;
constexpr double uLid = 0.4;
constexpr double reynolds = 1000;
constexpr double tau = 3. * uLid * (dimX-1) / reynolds + 0.5;
constexpr double omega = 1. / tau;
DataCellBuffer pop(dimX, dimY);
FluidBuffer fluid(dimX, dimY);
void init() {
for ( std::size_t x = 0; x < dimX; ++x ) {
for ( std::size_t y = 0; y < dimY; ++y ) {
fluid.density(x,y) = 1.0;
fluid.velocity(x,y) = { 0.0, 0.0 };
static_cast<Cell&>(pop.curr(x,y)).equilibrize(
fluid.density(x,y), fluid.velocity(x,y));
static_cast<Cell&>(pop.prev(x,y)).equilibrize(
fluid.density(x,y), fluid.velocity(x,y));
}
}
}
void computeLbmStep() {
pop.swap();
for ( std::size_t x = 0; x < dimX; ++x ) {
for ( std::size_t y = 0; y < dimY; ++y ) {
streamFluidCell(pop, x, y);
}
}
// moving top wall
for ( std::size_t x = 0; x < dimX; ++x ) {
computeMovingWallCell(pop, {x, dimY-1}, {0, -1}, {uLid, 0});
}
// straight wall cell bounce back
for ( std::size_t x = 1; x < dimX-1; ++x ) {
computeWallCell(pop, {x, 0}, { 0, 1});
}
for ( std::size_t y = 1; y < dimY-1; ++y ) {
computeWallCell(pop, {0, y}, { 1, 0});
computeWallCell(pop, {dimX-1, y}, {-1, 0});
}
// edge wall cell bounce back
computeWallCell(pop, {0, 0 }, { 1, 1});
computeWallCell(pop, {dimX-1, 0 }, {-1, 1});
for ( std::size_t x = 0; x < dimX; ++x ) {
for ( std::size_t y = 0; y < dimY; ++y ) {
Cell& cell = static_cast<Cell&>(pop.curr(x,y));
fluid.density(x,y) = cell.sum();
fluid.velocity(x,y) = cell.velocity(fluid.density(x,y));
collideFluidCell(omega, pop, fluid, x, y);
}
}
}
int main() {
init();
std::cout << "Re: " << reynolds << std::endl;
std::cout << "uLid: " << uLid << std::endl;
std::cout << "tau: " << tau << std::endl;
std::cout << "omega: " << omega << std::endl;
for ( std::size_t t = 0; t <= 10000; ++t ) {
computeLbmStep();
if ( t % 1000 == 0 ) {
std::cout << ".";
std::cout.flush();
fluid.writeAsVTK("result/data_t" + std::to_string(t) + ".vtk");
}
}
std::cout << std::endl;
}
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