From b4a61621fc1d2d6350c8f700ee3196950e476000 Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Wed, 10 Oct 2018 22:15:48 +0200
Subject: Separate examples

---
 cavity2d.cc | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 cavity2d.cc

(limited to 'cavity2d.cc')

diff --git a/cavity2d.cc b/cavity2d.cc
new file mode 100644
index 0000000..0006252
--- /dev/null
+++ b/cavity2d.cc
@@ -0,0 +1,89 @@
+#include <iostream>
+#include <vector>
+#include <string>
+#include <algorithm>
+
+#include "lbm.h"
+#include "boundary_conditions.h"
+
+constexpr std::size_t dimX = 64;
+constexpr std::size_t dimY = dimX;
+
+constexpr double uLid     = 0.1;
+constexpr double reynolds = 100;
+
+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);
+		}
+	}
+
+	// straight wall cell bounce back
+	for ( std::size_t x = 0; x < dimX; ++x ) {
+		computeZouHeVelocityWallCell(pop, {x, dimY-1}, { 0,-1}, uLid);
+	}
+	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;
+
+	for ( std::size_t t = 0; t <= 6000; ++t ) {
+		computeLbmStep();
+
+		if ( t % 100 == 0 ) {
+			std::cout << ".";
+			std::cout.flush();
+			fluid.writeAsVTK("result/data_t" + std::to_string(t) + ".vtk");
+		}
+	}
+
+	std::cout << std::endl;
+}
-- 
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