Bring in some more structure

1 files changed, 48 insertions, 0 deletions

diff --git a/src/boundary_conditions.h b/src/boundary_conditions.h
new file mode 100644
index 0000000..c825c32
--- /dev/null
+++ b/src/boundary_conditions.h
@@ -0,0 +1,48 @@
+#pragma once
+
+#include "vector.h"
+#include "data_cell_buffer.h"
+
+std::pair<Vector<int>, Vector<int>> neighbors(Vector<int> v) {
+	if ( v[0] == 0 ) {
+		return {
+			{ -1, v[1] },
+			{  1, v[1] }
+		};
+	} else if ( v[1] == 0 ) {
+		return {
+			{ v[0], -1 },
+			{ v[0],  1 }
+		};
+	} else {
+		return {
+			{    0, v[1] },
+			{ v[0], 0    }
+		};
+	}
+}
+
+void computeWallCell(DataCellBuffer& pop, Vector<std::size_t> cell, Vector<int> normal) {
+	const auto [neighborA, neighborB] = neighbors(normal);
+
+	pop.curr(cell).get(neighborA) = pop.curr(cell).get(-neighborA);
+	pop.curr(cell).get(normal   ) = pop.curr(cell).get(-normal   );
+	pop.curr(cell).get(neighborB) = pop.curr(cell).get(-neighborB);
+}
+
+void computeZouHeVelocityWallCell(DataCellBuffer& pop, Vector<std::size_t> cell, Vector<int> normal, double vX) {
+	const auto [neighborA, neighborB] = neighbors(normal);
+
+	const double rho = pop.curr(cell).get(-1,0) + pop.curr(cell).get(0,0) + pop.curr(cell).get(1,0)
+		+ 2.*(
+			pop.curr(cell).get(-neighborA) +
+			pop.curr(cell).get(-normal   ) +
+			pop.curr(cell).get(-neighborB)
+		);
+
+	pop.curr(cell).get(neighborA) = pop.curr(cell).get(-neighborA)
+	                              + 0.5*( pop.curr(cell).get( 1,0) - pop.curr(cell).get(-1,0) - vX*rho );
+	pop.curr(cell).get(normal   ) = pop.curr(cell).get(-normal   );
+	pop.curr(cell).get(neighborB) = pop.curr(cell).get(-neighborB)
+	                              + 0.5*( pop.curr(cell).get(-1,0) - pop.curr(cell).get( 1,0) + vX*rho );
+}