Merge pull request #26314 from grmnptr/nsfvaction-fix-26313

Add error message if user tries to define forbidden velocity variable names in NSFVAction.

modules/navier_stokes/include/base/NSFVBase.h

@@ -3208,6 +3208,17 @@ NSFVBase<BaseType>::checkGeneralControlErrors()
   if (parameters().template get<MooseEnum>("porosity_interface_pressure_treatment") != "bernoulli")
     checkDependentParameterError("porosity_interface_pressure_treatment",
                                  {"pressure_allow_expansion_on_bernoulli_faces"});
+
+  if (!_create_velocity && _porous_medium_treatment)
+    for (const auto & name : NS::velocity_vector)
+    {
+      const auto & it = std::find(_velocity_name.begin(), _velocity_name.end(), name);
+      if (it != _velocity_name.end())
+        paramError("velocity_variable",
+                   "For porous medium simulations, functor name " + *it +
+                       " is already reserved for the automatically-computed interstitial velocity. "
+                       "Please choose another name for your external velocity variable!");
+    }
 }
 
 template <class BaseType>

modules/navier_stokes/test/tests/finite_volume/ins/action/errors/tests

@@ -208,6 +208,15 @@
     expect_err = "The number of velocity variable names supplied to the NSFVAction is not 2 \(mesh "
                  "dimension\) or 3!"
   []
+  [velocity-name-error]
+    type = 'RunException'
+    input = 2d-rc-error-action-no-scalar.i
+    requirement = 'The system shall throw an error if the user supplies unallowed names for the external velocity components in a porous medium setting'
+    cli_args = "Modules/NavierStokesFV/velocity_variable='vel_x vel_y' "
+               "Modules/NavierStokesFV/porous_medium_treatment=true "
+               "Variables/vel_x/type=MooseVariableFVReal Variables/vel_y/type=MooseVariableFVReal"
+    expect_err = "For porous medium simulations, functor name vel\_x is already reserved for the automatically-computed interstitial velocity. Please choose another name for your external velocity variable!"
+  []
   [pressure-variable-error]
     type = 'RunException'
     input = 2d-rc-error-action.i