From 02a40ce77b221e8c8a6516e293c520f506d2308a Mon Sep 17 00:00:00 2001
From: Henry Weller <http://cfd.direct>
Date: Mon, 6 Dec 2021 11:33:48 +0000
Subject: [PATCH] transonicEntrainmentPressureFvPatchScalarField: Apply a fixed
 total-pressure condition for outflow

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

diff --git a/src/finiteVolume/fields/fvPatchFields/derived/transonicEntrainmentPressure/transonicEntrainmentPressureFvPatchScalarField.C b/src/finiteVolume/fields/fvPatchFields/derived/transonicEntrainmentPressure/transonicEntrainmentPressureFvPatchScalarField.C
index f6ff8e4d4c..5f703f1191 100644
--- a/src/finiteVolume/fields/fvPatchFields/derived/transonicEntrainmentPressure/transonicEntrainmentPressureFvPatchScalarField.C
+++ b/src/finiteVolume/fields/fvPatchFields/derived/transonicEntrainmentPressure/transonicEntrainmentPressureFvPatchScalarField.C
@@ -173,8 +173,13 @@ void Foam::transonicEntrainmentPressureFvPatchScalarField::updateCoeffs()
     const scalar Mb = 0.5;
 
     refValue() =
-        p0_/pow(scalar(1) - (0.5*gM1ByG)*psip*Unp*mag(Unp), 1/gM1ByG);
-    valueFraction() = 1 - min((Ma - Mb)/(1 - Mb), scalar(1));
+        p0_
+       /pow
+        (
+            1 - (0.5*gM1ByG)*psip*negPart(Unp)*mag(Unp),
+            1/gM1ByG
+        );
+    valueFraction() = 1 - min(max(Ma - Mb, scalar(0))/(1 - Mb), scalar(1));
 
     mixedFvPatchField<scalar>::updateCoeffs();
 }