FIX: handle zero dynamic pressure in reference value calculation (#2666)

Author: ayush4874

SU2_CFD/src/solvers/CEulerSolver.cpp

@@ -1445,6 +1445,11 @@ void CEulerSolver::SetReferenceValues(const CConfig& config) {
   }
 
   DynamicPressureRef = 0.5 * Density_Inf * RefVel2;
+
+  if (DynamicPressureRef < EPS) {
+    DynamicPressureRef = 1.0;
+  }
+
   AeroCoeffForceRef =  DynamicPressureRef * config.GetRefArea();
 
 }

SU2_CFD/src/solvers/CIncEulerSolver.cpp

@@ -945,6 +945,11 @@ void CIncEulerSolver::SetReferenceValues(const CConfig& config) {
   }
 
   DynamicPressureRef = 0.5 * RefDensity * RefVel2;
+
+  if (DynamicPressureRef < EPS) {
+    DynamicPressureRef = 1.0;
+  }
+
   AeroCoeffForceRef =  DynamicPressureRef * config.GetRefArea();
 
 }

SU2_CFD/src/solvers/CNEMOEulerSolver.cpp

@@ -1387,6 +1387,11 @@ void CNEMOEulerSolver::SetNondimensionalization(CConfig *config, unsigned short
 void CNEMOEulerSolver::SetReferenceValues(const CConfig& config) {
 
   DynamicPressureRef = 0.5 * Density_Inf * GeometryToolbox::SquaredNorm(nDim, Velocity_Inf);
+
+  if (DynamicPressureRef < EPS) {
+    DynamicPressureRef = 1.0;
+  }
+
   AeroCoeffForceRef =  DynamicPressureRef * config.GetRefArea();
 
 }