implement max_abs_speed_naive

src/equations/compressible_euler_multicomponent_abstract_2d.jl

@@ -454,6 +454,36 @@ end
     λ_max = max(abs(v_ll), abs(v_rr)) + max(c_ll, c_rr)
 end
 
+@inline function max_abs_speed_naive(u_ll, u_rr, normal_direction::AbstractVector,
+    equations::AbstractCompressibleEulerMulticomponentEquations{2})
+
+    rho_v1_ll, rho_v2_ll = u_ll
+    rho_v1_rr, rho_v2_rr = u_rr
+
+    # Get the density and gas gamma
+    rho_ll = density(u_ll, equations)
+    rho_rr = density(u_rr, equations)
+    gamma_ll = totalgamma(u_ll, equations)
+    gamma_rr = totalgamma(u_rr, equations)
+
+    # Calculate normal velocities and sound speed
+    v1_ll = rho_v1_ll / rho_ll
+    v2_ll = rho_v2_ll / rho_ll
+    v1_rr = rho_v1_rr / rho_rr
+    v2_rr = rho_v2_rr / rho_rr
+
+    v_ll = (v1_ll * normal_direction[1] + v2_ll * normal_direction[2])
+    v_rr = (v1_rr * normal_direction[1] + v2_rr * normal_direction[2])
+
+    # Compute the sound speeds on the left and right
+    p_ll = pressure(u_ll, equations)
+    c_ll = sqrt(gamma_ll * p_ll / rho_ll)
+    p_rr = pressure(u_rr, equations)
+    c_rr = sqrt(gamma_rr * p_rr / rho_rr)
+
+    λ_max = max(abs(v_ll), abs(v_rr)) + max(c_ll, c_rr)
+end
+
 @inline function max_abs_speeds(u,
                                 equations::AbstractCompressibleEulerMulticomponentEquations{2})
     rho_v1, rho_v2 = u