re-add naive version

Author: benegee

src/equations/covariant_advection.jl

@@ -110,9 +110,9 @@ end
 end
 
 # Maximum contravariant wave speed with respect to specific basis vector
-@inline function Trixi.max_abs_speed_naive(u_ll, u_rr, aux_vars_ll, aux_vars_rr,
-                                           orientation::Integer,
-                                           equations::CovariantLinearAdvectionEquation2D)
+@inline function Trixi.max_abs_speed(u_ll, u_rr, aux_vars_ll, aux_vars_rr,
+                                     orientation::Integer,
+                                     equations::CovariantLinearAdvectionEquation2D)
     vcon_ll = velocity_contravariant(u_ll, equations)  # Contravariant components on left side
     vcon_rr = velocity_contravariant(u_rr, equations)  # Contravariant components on right side
     return max(abs(vcon_ll[orientation]), abs(vcon_rr[orientation]))

src/equations/covariant_shallow_water.jl

@@ -217,9 +217,9 @@ end
 end
 
 # Maximum wave speed along the normal direction in reference space
-@inline function Trixi.max_abs_speed_naive(u_ll, u_rr, aux_vars_ll, aux_vars_rr,
-                                           orientation,
-                                           equations::AbstractCovariantShallowWaterEquations2D)
+@inline function Trixi.max_abs_speed(u_ll, u_rr, aux_vars_ll, aux_vars_rr,
+                                     orientation,
+                                     equations::AbstractCovariantShallowWaterEquations2D)
     # Geometric variables
     Gcon_ll = metric_contravariant(aux_vars_ll, equations)
     Gcon_rr = metric_contravariant(aux_vars_rr, equations)

src/equations/shallow_water_3d.jl

@@ -386,6 +386,27 @@ function clean_solution_lagrange_multiplier!(u, equations::ShallowWaterEquations
     u[4] -= normal_direction[3] * x_dot_div_f
 end
 
+@inline function Trixi.max_abs_speed_naive(u_ll, u_rr, normal_direction::AbstractVector,
+                                           equations::ShallowWaterEquations3D)
+    # Extract and compute the velocities in the normal direction
+    v1_ll, v2_ll, v3_ll = velocity(u_ll, equations)
+    v1_rr, v2_rr, v3_rr = velocity(u_rr, equations)
+    v_ll = v1_ll * normal_direction[1] + v2_ll * normal_direction[2] +
+           v3_ll * normal_direction[3]
+    v_rr = v1_rr * normal_direction[1] + v2_rr * normal_direction[2] +
+           v3_rr * normal_direction[3]
+
+    # Compute the wave celerity on the left and right
+    h_ll = waterheight(u_ll, equations)
+    h_rr = waterheight(u_rr, equations)
+
+    c_ll = sqrt(max(equations.gravity * h_ll, 0.0f0))
+    c_rr = sqrt(max(equations.gravity * h_rr, 0.0f0))
+
+    # The normal velocities are already scaled by the norm
+    return max(abs(v_ll), abs(v_rr)) + max(c_ll, c_rr) * norm(normal_direction)
+end
+
 @inline function Trixi.max_abs_speed(u_ll, u_rr, normal_direction::AbstractVector,
                                      equations::ShallowWaterEquations3D)
     # Extract and compute the velocities in the normal direction