From c6d0d1af39c2b907893a729627f42c86df1a572a Mon Sep 17 00:00:00 2001
From: Chris Greenshields <https://cfd.direct>
Date: Sat, 27 Jul 2024 16:57:55 +0100
Subject: [PATCH] snappyHexMeshConfig: improve surface projections with
 '-cylindricalBackground' option

---
 .../blockMeshCylindricalConfiguration.C                  | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/applications/utilities/preProcessing/snappyHexMeshConfig/blockMeshCylindricalConfiguration.C b/applications/utilities/preProcessing/snappyHexMeshConfig/blockMeshCylindricalConfiguration.C
index a0e583ece7..d080ecea90 100644
--- a/applications/utilities/preProcessing/snappyHexMeshConfig/blockMeshCylindricalConfiguration.C
+++ b/applications/utilities/preProcessing/snappyHexMeshConfig/blockMeshCylindricalConfiguration.C
@@ -264,8 +264,13 @@ void Foam::blockMeshCylindricalConfiguration::writeGeometry()
     List<word> geometries {"rotatingZone", "outer"};
     List<word> dims {"radIn", "radOut"};
 
-    const scalar zMin = roundDown(bb_.min().z(), 10);
-    const scalar zMax = roundUp(bb_.max().z(), 10);
+    scalar zMin = roundDown(bb_.min().z(), 10);
+    scalar zMax = roundUp(bb_.max().z(), 10);
+
+    // Extend the bounds to avoid bad projections
+    const scalar span = zMax - zMin;
+    zMax += span;
+    zMin -= span;
 
     forAll(geometries, i)
     {