From 4b53cc35e4430a2825ca2a91fec1fec4d2542d85 Mon Sep 17 00:00:00 2001
From: smpark7 <park_cg@live.com>
Date: Tue, 4 Jun 2024 11:06:19 -0700
Subject: [PATCH] Assign a protected variable name to the milne extrapolation
 coefficient value

---
 include/bcs/VacuumConcBC.h | 7 ++++++-
 src/bcs/VacuumConcBC.C     | 4 +---
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/include/bcs/VacuumConcBC.h b/include/bcs/VacuumConcBC.h
index 1a087b2bf..0b92826f6 100644
--- a/include/bcs/VacuumConcBC.h
+++ b/include/bcs/VacuumConcBC.h
@@ -34,6 +34,11 @@ class VacuumConcBC : public IntegratedBC, public ScalarTransportBase
     MILNE
   };
 
-  /// Ratio of u to du/dn
+  // Ratio of u to du/dn
   Real _alpha;
+
+  // Milne vacuum boundary extrapolation coefficient
+  // Derived from the exact analytical solution to the Milne problem. See MooseDocs-based
+  // documentation for more information.
+  Real _milne_extrapolation_coefficient = 3 * 0.710446;
 };
diff --git a/src/bcs/VacuumConcBC.C b/src/bcs/VacuumConcBC.C
index 42a951133..71718bc41 100644
--- a/src/bcs/VacuumConcBC.C
+++ b/src/bcs/VacuumConcBC.C
@@ -25,9 +25,7 @@ VacuumConcBC::VacuumConcBC(const InputParameters & parameters)
       _alpha = std::sqrt(3.);
       break;
     case MILNE:
-      // Derived from the exact analytical solution to the Milne problem. See MooseDocs-based
-      // documentation for more information.
-      _alpha = 3 * 0.710446;
+      _alpha = _milne_extrapolation_coefficient;
       break;
   }
 }