Introduced changes required to make isoAdvector and interIsoFoam work with...

Introduced changes required to make isoAdvector and interIsoFoam work with morphing meshes: 1) In the alphaEqn.H U is made relative to mesh motion before the interface advection step, 2) in isoAdvection::advect() alpha must be multiplied by Vsc0()/Vsc(). Implementation tested and verified with 1) a spherical interface in a cubic domain with no flow, where the domain walls are squeezed together and 2) a spherical interfacee inside the sloshingCylinder, again with no flow, so the sphere should stay spherical, which it does.

applications/solvers/multiphase/interIsoFoam/alphaEqn.H

 {
+    // Temporarily making U relative to mesh motion
+    if (mesh.moving())
+    {
+        U -= fvc::reconstruct(mesh.phi());
+    }
+
     // Updating alpha1
     advector.advect();
+
+    // Making U absolute again after advection step
+    if (mesh.moving())
+    {
+        U += fvc::reconstruct(mesh.phi());
+    }
+
     #include "rhofs.H"
     rhoPhi = advector.getRhoPhi(rho1f, rho2f);
 

src/finiteVolume/fvMatrices/solvers/isoAdvection/isoAdvection/isoAdvection.C

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
                 isoAdvector | Copyright (C) 2016-2017 DHI
-              Modified work | Copyright (C) 2018 Johan Roenby
+              Modified work | Copyright (C) 2019 Johan Roenby
 -------------------------------------------------------------------------------
 
 License
@@ -852,6 +852,12 @@ void Foam::isoAdvection::advect()
     // Do the isoAdvection on surface cells
     timeIntegratedFlux();
 
+    // Adjust alpha for mesh motion
+    if (mesh_.moving())
+    {
+        alpha1In_ *= (mesh_.Vsc0()/mesh_.Vsc());
+    }
+
     // Adjust dVf for unbounded cells
     limitFluxes();