Fix fvoptions seg fault (#369)

* Called fvOptions constrain to avoid seg fault.

* Fixed an issue.

src/adjoint/DAResidual/DAResidualRhoSimpleFoam.C

@@ -69,6 +69,14 @@ DAResidualRhoSimpleFoam::DAResidualRhoSimpleFoam(
         Info << "molWeight " << molWeight_ << endl;
         Info << "Cp " << Cp_ << endl;
     }
+
+    // this is just a dummy call because we need to run the constrain once 
+    // to initialize fvOptions, before we can use it. Otherwise, we may get
+    // a seg fault when we call fvOptions_.correct(U_) in updateIntermediateVars
+    fvVectorMatrix UEqn(
+        fvm::div(phi_, U_)
+        - fvOptions_(rho_, U_));
+    fvOptions_.constrain(UEqn);
 }
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 

src/adjoint/DAResidual/DAResidualSimpleFoam.C

@@ -44,6 +44,14 @@ DAResidualSimpleFoam::DAResidualSimpleFoam(
     {
         hasFvSource_ = 1;
     }
+
+    // this is just a dummy call because we need to run the constrain once 
+    // to initialize fvOptions, before we can use it. Otherwise, we may get
+    // a seg fault when we call fvOptions_.correct(U_) in updateIntermediateVars
+    fvVectorMatrix UEqn(
+        fvm::div(phi_, U_)
+        - fvOptions_(U_));
+    fvOptions_.constrain(UEqn);
 }
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

src/adjoint/DAResidual/DAResidualSimpleTFoam.C

@@ -59,6 +59,14 @@ DAResidualSimpleTFoam::DAResidualSimpleTFoam(
             false));
     Pr_ = readScalar(transportProperties.lookup("Pr"));
     Prt_ = readScalar(transportProperties.lookup("Prt"));
+
+    // this is just a dummy call because we need to run the constrain once 
+    // to initialize fvOptions, before we can use it. Otherwise, we may get
+    // a seg fault when we call fvOptions_.correct(U_) in updateIntermediateVars
+    fvVectorMatrix UEqn(
+        fvm::div(phi_, U_)
+        - fvOptions_(U_));
+    fvOptions_.constrain(UEqn);
 }
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //