[geomech] remove divU from vol vars and output

After using the new porosity law, this is overhead for output purposes
at the moment. If this output is desired it can be added manually.

dumux/geomechanics/poroelastic/volumevariables.hh

@@ -79,12 +79,6 @@ public:
         setSolidTemperature_(problem, elemSol);
         // update the density of the solid phase
         solidState_.setDensity(SolidSystem::density(solidState_));
-
-        // compute divergence of diplacement for this scv
-        divU_ = 0.0;
-        const auto gradU = evalGradients(element, element.geometry(), problem.fvGridGeometry(), elemSol, scv.center());
-        for (int dir = 0; dir < Element::Geometry::mydimension; ++dir)
-            divU_ += gradU[Indices::u(dir)][dir];
     }
 
     //! Return the average porosity \f$\mathrm{[-]}\f$ within the scv.
@@ -95,11 +89,7 @@ public:
     Scalar porosity() const
     { return solidState_.porosity(); }
 
-    //! Returns the divergence of u within this scv
-    Scalar divU() const
-    { return divU_; }
-
-    //! Returns the permeability within the scv in \f$[m]\f$.
+    //! Returns the permeability within the scv in \f$[m^2]\f$.
     Scalar displacement(unsigned int dir) const
     { return priVars_[ Indices::momentum(dir) ]; }
 
@@ -161,7 +151,6 @@ private:
     { solidState_.setTemperature(problem.temperature()); }
 
     // data members
-    Scalar divU_;
     Scalar extrusionFactor_;
     PrimaryVariables priVars_;
     SolidState solidState_;

dumux/geomechanics/poroelastic/vtkoutputfields.hh

@@ -37,7 +37,6 @@ public:
     static void init(VtkOutputModule& vtk)
     {
         vtk.addVolumeVariable([](const auto& volVars){ return volVars.displacement(); }, "u");
-        vtk.addVolumeVariable([](const auto& volVars){ return volVars.divU(); }, "divU");
         vtk.addVolumeVariable([](const auto& volVars){ return volVars.porosity(); }, "porosity");
     }
 };

test/references/poroelasticbox-reference.vtu

@@ -2,20 +2,7 @@
 <VTKFile type="UnstructuredGrid" version="0.1" byte_order="LittleEndian">
   <UnstructuredGrid>
     <Piece NumberOfCells="100" NumberOfPoints="121">
-      <PointData Scalars="divU" Vectors="u">
-        <DataArray type="Float32" Name="divU" NumberOfComponents="1" format="ascii">
-          1.03018 4.31628 1.13699 3.12086 5.98734 4.05203 5.39399 3.56227 2.75709 1.7952 -0.925811 -0.623187
-          -4.25901 -2.82056 -5.98019 -4.00904 -5.44047 -3.78356 -2.85233 -2.26772 -1.03268 -1.14381 0.850548 0.691137
-          0.516076 0.32864 0.134554 -0.0631484 -0.262281 -0.461096 -0.657845 -0.854738 -0.858747 0.231992 -2.01571 -3.24177
-          -3.05161 -1.58592 0.528213 2.41507 3.28421 2.73113 0.889488 -0.239324 -0.485967 -3.96423 -5.77447 -5.27783
-          -2.70607 0.920505 4.17942 5.78745 5.08895 2.30371 0.481644 -1.02811 -4.40834 -6.1109 -5.49569 -2.79631
-          0.962682 4.35375 6.08967 5.51364 2.84813 1.02816 -1.18662 -3.17723 -4.1212 -3.6207 -1.82134 0.638844
-          2.8712 4.07498 3.84249 2.31448 1.19117 -0.901086 -0.740581 -0.565618 -0.369383 -0.153144 0.0738811 0.299603
-          0.514138 0.714246 0.906097 0.908948 -0.279364 1.97083 3.19458 3.01476 1.57185 -0.513503 -2.37511 -3.2301
-          -2.67608 -0.841163 0.288449 0.458683 3.91091 5.71737 5.23698 2.69765 -0.892034 -4.12352 -5.72345 -5.03643
-          -2.27321 -0.451072 0.760231 4.10763 5.83294 5.29515 2.7159 -0.907401 -4.17938 -5.83797 -5.23428 -2.57987
-          -0.757736
-        </DataArray>
+      <PointData Scalars="porosity" Vectors="u">
         <DataArray type="Float32" Name="porosity" NumberOfComponents="1" format="ascii">
           0.609054 1.59488 0.641098 1.23626 2.0962 1.51561 1.9182 1.36868 1.12713 0.838561 0.0222568 0.113044
           0 0 0 0 0 0 0 0 0 0 0.555164 0.507341