From c17887cab8fb94781ec9d978c0d285b4426f0ec4 Mon Sep 17 00:00:00 2001
From: Marc Fehling <mafehling.git@gmail.com>
Date: Mon, 29 Nov 2021 18:34:25 -0700
Subject: [PATCH] Use internal rotation matrix for airfoil.

---
 source/grid/grid_generator.cc | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/source/grid/grid_generator.cc b/source/grid/grid_generator.cc
index 7d961f01ba..1625a626b6 100644
--- a/source/grid/grid_generator.cc
+++ b/source/grid/grid_generator.cc
@@ -28,6 +28,8 @@
 #include <deal.II/grid/tria_accessor.h>
 #include <deal.II/grid/tria_iterator.h>
 
+#include <deal.II/physics/transformations.h>
+
 #include <array>
 #include <cmath>
 #include <limits>
@@ -954,14 +956,10 @@ namespace GridGenerator
           std::vector<bool> vertex_processed(tria.n_vertices(), false);
 
           // rotation matrix for clockwise rotation of block 1 by angle gamma
-          Tensor<2, 2, double> rotation_matrix_1, rotation_matrix_2;
-
-          rotation_matrix_1[0][0] = +std::cos(-gamma);
-          rotation_matrix_1[0][1] = -std::sin(-gamma);
-          rotation_matrix_1[1][0] = +std::sin(-gamma);
-          rotation_matrix_1[1][1] = +std::cos(-gamma);
-
-          rotation_matrix_2 = transpose(rotation_matrix_1);
+          const Tensor<2, 2, double> rotation_matrix_1 =
+            Physics::Transformations::Rotations::rotation_matrix_2d(-gamma);
+          const Tensor<2, 2, double> rotation_matrix_2 =
+            transpose(rotation_matrix_1);
 
           // horizontal offset in order to place coarse-grid node A in the
           // origin
-- 
2.39.5