Address Peter's review

- face velocity -> volumetric face flux due to A term

Co-authored-by: Peter German <[email protected]>

Apply suggestions from code review

Co-authored-by: Peter German <[email protected]>

modules/navier_stokes/doc/content/source/linearfvkernels/LinearFVScalarAdvection.md

@@ -12,7 +12,7 @@ For FV, the integral of the advection term of scalar $C_i$ over a cell can be ex
 
 where $C_{if}$ is the face value of the scalar concentration. An interpolation scheme (e.g. upwind) can be used to compute the face value. This kernel adds the face contribution for each face $f$ to the right hand side and matrix.
 
-The face mass flux $(\vec{u}\cdot \vec{n})_{RC}$ is provided by the [RhieChowMassFlux.md] object which uses pressure
+The volumetric face flux $(\vec{u}\cdot \vec{n})_{RC}$ is provided by the [RhieChowMassFlux.md] object which uses pressure
 gradients and the discrete momentum equation to compute face velocities and mass fluxes.
 For more information on the expression that is used, see [SIMPLE.md].
 

modules/navier_stokes/doc/content/source/physics/WCNSLinearFVScalarTransportPhysics.md

@@ -15,7 +15,7 @@ where:
 - $\phi_i$ is the i-th scalar quantity
 - \mathbf{v} is the advecting velocity
 - $k_i$ the i-th scalar diffusivity
-- $Q_i$ is the i-th precursor source
+- $Q_i$ is the i-th scalar source
 - $\lambda_i$ is a reaction coefficient. It should be negative for a loss term
 
 The kernels created are:

modules/navier_stokes/include/linearfvkernels/LinearFVScalarAdvection.h

@@ -47,7 +47,7 @@ class LinearFVScalarAdvection : public LinearFVFluxKernel
 
   /// Container for the velocity on the face which will be reused in the advection term's
   /// matrix and right hand side contribution
-  Real _face_velocity;
+  Real _volumetric_face_flux;
 
   /// The interpolation method to use for the advected quantity
   Moose::FV::InterpMethod _advected_interp_method;

modules/navier_stokes/include/userobjects/RhieChowMassFlux.h

@@ -46,8 +46,8 @@ class RhieChowMassFlux : public GeneralUserObject,
 
   /// Get the face velocity times density (used in advection terms)
   Real getMassFlux(const FaceInfo & fi) const;
-  /// Get the face velocity (used in advection terms)
-  Real getFaceVelocity(const FaceInfo & fi) const;
+  /// Get the volumetric face flux (used in advection terms)
+  Real getVolumetricFaceFlux(const FaceInfo & fi) const;
 
   /// Initialize the container for face velocities
   void initFaceMassFlux();

modules/navier_stokes/src/linearfvkernels/LinearFVScalarAdvection.C

@@ -31,21 +31,21 @@ LinearFVScalarAdvection::LinearFVScalarAdvection(const InputParameters & params)
   : LinearFVFluxKernel(params),
     _mass_flux_provider(getUserObject<RhieChowMassFlux>("rhie_chow_user_object")),
     _advected_interp_coeffs(std::make_pair<Real, Real>(0, 0)),
-    _face_velocity(0.0)
+    _volumetric_face_flux(0.0)
 {
   Moose::FV::setInterpolationMethod(*this, _advected_interp_method, "advected_interp_method");
 }
 
 Real
 LinearFVScalarAdvection::computeElemMatrixContribution()
 {
-  return _advected_interp_coeffs.first * _face_velocity * _current_face_area;
+  return _advected_interp_coeffs.first * _volumetric_face_flux * _current_face_area;
 }
 
 Real
 LinearFVScalarAdvection::computeNeighborMatrixContribution()
 {
-  return _advected_interp_coeffs.second * _face_velocity * _current_face_area;
+  return _advected_interp_coeffs.second * _volumetric_face_flux * _current_face_area;
 }
 
 Real
@@ -71,7 +71,7 @@ LinearFVScalarAdvection::computeBoundaryMatrixContribution(const LinearFVBoundar
   // We support internal boundaries too so we have to make sure the normal points always outward
   const auto factor = (_current_face_type == FaceInfo::VarFaceNeighbors::ELEM) ? 1.0 : -1.0;
 
-  return boundary_value_matrix_contrib * factor * _face_velocity * _current_face_area;
+  return boundary_value_matrix_contrib * factor * _volumetric_face_flux * _current_face_area;
 }
 
 Real
@@ -84,7 +84,7 @@ LinearFVScalarAdvection::computeBoundaryRHSContribution(const LinearFVBoundaryCo
   const auto factor = (_current_face_type == FaceInfo::VarFaceNeighbors::ELEM ? 1.0 : -1.0);
 
   const auto boundary_value_rhs_contrib = adv_bc->computeBoundaryValueRHSContribution();
-  return -boundary_value_rhs_contrib * factor * _face_velocity * _current_face_area;
+  return -boundary_value_rhs_contrib * factor * _volumetric_face_flux * _current_face_area;
 }
 
 void
@@ -94,10 +94,10 @@ LinearFVScalarAdvection::setupFaceData(const FaceInfo * face_info)
 
   // Caching the velocity on the face which will be reused in the advection term's matrix and right
   // hand side contributions
-  _face_velocity = _mass_flux_provider.getFaceVelocity(*face_info);
+  _volumetric_face_flux = _mass_flux_provider.getVolumetricFaceFlux(*face_info);
 
   // Caching the interpolation coefficients so they will be reused for the matrix and right hand
   // side terms
   _advected_interp_coeffs =
-      interpCoeffs(_advected_interp_method, *_current_face_info, true, _face_velocity);
+      interpCoeffs(_advected_interp_method, *_current_face_info, true, _volumetric_face_flux);
 }

modules/navier_stokes/src/userobjects/RhieChowMassFlux.C

@@ -235,15 +235,16 @@ RhieChowMassFlux::getMassFlux(const FaceInfo & fi) const
 }
 
 Real
-RhieChowMassFlux::getFaceVelocity(const FaceInfo & fi) const
+RhieChowMassFlux::getVolumetricFaceFlux(const FaceInfo & fi) const
 {
   const Moose::FaceArg face_arg{&fi,
                                 /*limiter_type=*/Moose::FV::LimiterType::CentralDifference,
                                 /*elem_is_upwind=*/true,
                                 /*correct_skewness=*/false,
-                                &fi.elem()};
+                                &fi.elem(),
+                                /*state_limiter*/ nullptr};
   const Real face_rho = _rho(face_arg, Moose::currentState());
-  return _face_mass_flux.evaluate(&fi) / face_rho;
+  return libmesh_map_find(_face_mass_flux, fi.id()) / face_rho;
 }
 
 void