[skip ci] add test case for mortar bc's for 2D navier equation using n-t coordinate system

Author: raback

fem/src/SolverUtils.F90

@@ -9895,7 +9895,8 @@ SUBROUTINE AverageBoundaryNormals( Model, VariableName,    &
               CALL TangentDirections( BoundaryNormals(k,:),  &
                   BoundaryTangent1(k,:), BoundaryTangent2(k,:) )
               IF( RotSystem ) THEN
-                IF( SUM(BoundaryTangent2(k,:)) < 0.0 ) THEN
+                ! We want to always have n_z as positive in cylinder system.
+                IF( BoundaryTangent2(k,3) < 0.0 ) THEN
                   BoundaryTangent2(k,:) = -BoundaryTangent2(k,:)
                 END IF
               ELSE IF( LhsSystem ) THEN

fem/tests/RotatingBCNavier2D/CMakeLists.txt

@@ -0,0 +1,8 @@
+INCLUDE(test_macros)
+INCLUDE_DIRECTORIES(${CMAKE_BINARY_DIR}/fem/src)
+
+CONFIGURE_FILE( case.sif case.sif COPYONLY)
+
+file(COPY ELMERSOLVER_STARTINFO mortar.msh DESTINATION "${CMAKE_CURRENT_BINARY_DIR}/")
+
+ADD_ELMER_TEST(RotatingBCNavier2D LABELS mortar)

fem/tests/RotatingBCNavier2D/ELMERSOLVER_STARTINFO

@@ -0,0 +1 @@
+case.sif

fem/tests/RotatingBCNavier2D/case.sif

@@ -0,0 +1,189 @@
+! Test case for 2D nonconforming mortar elements
+! This cases solves the linear elasticity equation using
+! normal-tangential coordinate system.
+! Can be activated for Galerkin Projector = True / False.
+!
+! P.R. 5.3.2026
+
+Header
+  CHECK KEYWORDS Warn
+  Mesh DB "." "mortar"
+  Include Path ""
+  Results Directory "results"
+End
+
+$omega = 1.0 
+$phi0 = 33.0
+
+Simulation
+  Max Output Level = 5
+  Coordinate System = Cartesian
+  Simulation Type = Scanning 
+  Steady State Max Iterations = 1
+  Output Intervals = 1
+  
+  Timestep Intervals = 3 !180
+  Output Intervals = 1
+
+  Post File = case.vtu
+  Ascii Output = True
+
+  Simulation Timing = Logical True
+
+! This make the treatment of normals consistent such that all normals
+! point consistently out of cylinder axis. 
+  Use Cylinder System = Logical True
+End 
+
+
+Body 1
+  Target Bodies(1) = 1
+  Name = "Stator"
+  Equation = 1
+  Material = 1
+  Body Force = 1
+  Initial Condition = 1
+End
+
+Body 2
+  Target Bodies(1) = 2
+  Name = "Rotor-Hot"
+  Equation = 1
+  Material = 1
+  Body Force = 2
+  Initial Condition = 1
+End
+
+Body 3
+  Target Bodies(1) = 3
+  Name = "Rotor-Cold"
+  Equation = 1
+  Material = 1
+  Body Force = 3
+  Initial Condition = 1
+End
+
+
+Solver 1
+  Exec Solver = Before Timestep
+  Equation = MeshDeform
+  Procedure = "RigidMeshMapper" "RigidMeshMapper"
+  Cumulative Displacements = Logical False
+  Translate Before Rotate = Logical True
+End
+
+
+Solver 2
+  Equation = StessEq
+  Procedure = "StressSolve" "StressSolver"
+  Variable = -dofs 2 Displacement 
+  Steady State Convergence Tolerance = 1.0e-5
+
+  Nonlinear System Max Iterations = 1
+  Nonlinear System Consistent Norm = True
+
+  Linear System Solver = direct
+  Linear System Direct Method = umfpack
+
+  Optimize Bandwidth = False
+
+  Apply Mortar BCs = Logical True
+
+  Displace Mesh = False
+End
+
+Solver 3
+! Settings mainly for timing and verification
+  Exec Solver = never
+
+  Equation = SaveScalars
+  Procedure = "SaveData" "SaveScalars"
+
+  Filename = scalars.dat
+
+  Variable 1 = Temperature
+  Operator 1 = dofs
+  Operator 2 = partitions
+  Operator 3 = min
+  Operator 4 = max
+  Operator 5 = norm
+  Operator 6 = cpu time
+  Operator 7 = wall time
+
+! Reduce just to one file when parallel
+  Parallel Reduce = Logical True
+  Default Parallel Operator = String max
+  Parallel Operator 1 = String sum
+End 
+ 
+
+Equation 1
+  Name = "Heat"
+  Active Solvers(1) = 2
+End
+
+Material 1
+  Name = "Ideal"
+  Density = 1
+  Poisson Ratio = 0.3  ! makes the equation diagonal!
+  Youngs Modulus = 1.0e3
+End
+
+Body Force 1
+  Name = "MoveToLeft"
+  Mesh Translate 1 = -4.0
+End
+
+Body Force 2 
+  Name = "Hot Move"
+  Stress Bodyforce 1 = Variable "Coordinate"
+    Real MATC "sqrt(tx(0)^2+tx(1)^2)"
+  Mesh Rotate 3 = Variable time 
+    Real MATC "omega*tx+phi0"
+End 
+
+Body Force 3
+  Name = "Cold Move"
+  Stress Bodyforce 1 = Variable "Coordinate"
+    Real MATC "-sqrt(tx(0)^2+tx(1)^2)"
+  Mesh Rotate 3 = Variable time 
+    Real MATC "omega*tx+phi0"
+End 
+
+Boundary Condition 1
+  Target Boundaries(4) = 10 11 12 13
+  Name = "Ambient"
+  Displacement 1 = 0.0
+  Displacement 2 = 0.0
+End
+
+Boundary Condition 2
+  Target Boundaries(4) = 6 7 8 9
+  Name = "Mortar Outside"
+
+! This makes the normals point always out from cylinder origin
+  Normal-Tangential Displacement = True
+  Rotational Normals = True
+End
+
+Boundary Condition 3
+  Target Boundaries(4) = 1 2 3 4
+  Name = "Mortar Inside"
+
+  Mortar BC = 2
+  Rotational Projector = True
+
+  Normal-Tangential Displacement = True
+  Rotational Normals = True
+
+! This gives almost the same results using strong projector
+  Galerkin Projector = True
+End
+
+Solver 2 :: Reference Norm = 5.74636514E-05
+
+
+!Material 1 :: Poisson Ratio = 0.0
+!Solver 2 :: Reference Norm = 5.28565365E-05
+
+