VoF solvers: New interfaceCompressionFvPatchScalarField BC and additional shear compression

Provides the additional compression necessary to ensure interface integrity
adjacent to a boundary at a low angle of incidence to the interface.  This is
particularly important when simulating planing hulls.

applications/solvers/multiphase/VoF/alphaEqn.H

@@ -65,6 +65,14 @@
         phic += (mixture.cAlpha()*icAlpha)*fvc::interpolate(mag(U));
     }
 
+    // Add the optional shear compression contribution
+    if (scAlpha > 0)
+    {
+        phic +=
+            scAlpha*mag(mesh.delta() & fvc::interpolate(symm(fvc::grad(U))));
+    }
+
+
     surfaceScalarField::Boundary& phicBf =
         phic.boundaryFieldRef();