incompressible/channelFoam, solver + tutorials

applications/solvers/incompressible/channelFoam/channelFoam.C

@@ -26,6 +26,10 @@ Application
 
 Description
     Incompressible LES solver for flow in a channel.
+    Consistent formulation without time-step and relaxation dependence by Jasak
+
+Author
+    Hrvoje Jasak, Wikki Ltd.  All rights reserved
 
 \*---------------------------------------------------------------------------*/
 
@@ -60,38 +64,41 @@ int main(int argc, char *argv[])
 
         sgsModel->correct();
 
-        fvVectorMatrix UEqn
+        // Convection-diffusion matrix
+        fvVectorMatrix HUEqn
         (
-            fvm::ddt(U)
-          + fvm::div(phi, U)
+            fvm::div(phi, U)
           + sgsModel->divDevBeff(U)
          ==
             flowDirection*gradP
         );
 
+        // Time derivative matrix
+        fvVectorMatrix ddtUEqn(fvm::ddt(U));
+
         if (momentumPredictor)
         {
-            solve(UEqn == -fvc::grad(p));
+            solve(ddtUEqn + HUEqn == -fvc::grad(p));
         }
 
+        // Prepare clean Ap without time derivative contribution
+        // HJ, 26/Oct/2015
+        volScalarField aU = HUEqn.A();
 
         // --- PISO loop
 
-        volScalarField rUA = 1.0/UEqn.A();
-
         for (int corr = 0; corr < nCorr; corr++)
         {
-            U = rUA*UEqn.H();
-            phi = (fvc::interpolate(U) & mesh.Sf())
-                + fvc::ddtPhiCorr(rUA, U, phi);
+            U = HUEqn.H()/aU;
+            phi = (fvc::interpolate(U) & mesh.Sf());
 
             adjustPhi(phi, U, p);
 
-            for (int nonOrth=0; nonOrth<=nNonOrthCorr; nonOrth++)
+            for (int nonOrth = 0; nonOrth <= nNonOrthCorr; nonOrth++)
             {
                 fvScalarMatrix pEqn
                 (
-                    fvm::laplacian(rUA, p) == fvc::div(phi)
+                    fvm::laplacian(1/aU, p) == fvc::div(phi)
                 );
 
                 pEqn.setReference(pRefCell, pRefValue);
@@ -111,13 +118,17 @@ int main(int argc, char *argv[])
                 }
             }
 
-            #include "continuityErrs.H"
+#           include "continuityErrs.H"
 
-            U -= rUA*fvc::grad(p);
+            // Note: cannot call H(U) here because the velocity is not complete
+            // HJ, 22/Jan/2016
+            U = 1.0/(aU + ddtUEqn.A())*
+                (
+                    U*aU - fvc::grad(p) + ddtUEqn.H()
+                );
             U.correctBoundaryConditions();
         }
 
-
         // Correct driving force for a constant mass flow rate
 
         // Extract the velocity in the flow direction
@@ -127,9 +138,9 @@ int main(int argc, char *argv[])
         // Calculate the pressure gradient increment needed to
         // adjust the average flow-rate to the correct value
         dimensionedScalar gragPplus =
-            (magUbar - magUbarStar)/rUA.weightedAverage(mesh.V());
+            (magUbar - magUbarStar)*aU.weightedAverage(mesh.V());
 
-        U += flowDirection*rUA*gragPplus;
+        U += gragPplus/aU*flowDirection;
 
         gradP += gragPplus;
 

tutorials/incompressible/channelFoam/channel395/system/fvSchemes

@@ -29,7 +29,7 @@ gradSchemes
 divSchemes
 {
     default         none;
-    div(phi,U)      Gauss linear;
+    div(phi,U)      Gauss linearUpwind Gauss linear;
     div(phi,k)      Gauss limitedLinear 1;
     div(phi,B)      Gauss limitedLinear 1;
     div(B)          Gauss linear;