prim2phys

src/DispersiveShallowWater.jl

@@ -64,7 +64,7 @@ export AbstractShallowWaterEquations,
        SvärdKalischEquations1D, SvaerdKalischEquations1D,
        SerreGreenNaghdiEquations1D, HyperbolicSerreGreenNaghdiEquations1D
 
-export prim2prim, prim2cons, cons2prim,
+export prim2prim, prim2cons, cons2prim, prim2phys,
        waterheight_total, waterheight,
        velocity, momentum, discharge,
        gravity_constant,

src/equations/equations.jl

@@ -349,7 +349,7 @@ of another set of equations and `Val{false}()` otherwise (default).
 For example, the [`HyperbolicSerreGreenNaghdiEquations1D`](@ref) are
 a hyperbolic approximation of the [`SerreGreenNaghdiEquations1D`](@ref).
 
-See also [`hyperbolic_approximation_limit`](@ref).
+See also [`hyperbolic_approximation_limit`](@ref) and [`prim2phys`](@ref).
 
 !!! note "Implementation details"
     This function is mostly used for some internal dispatch. For example,
@@ -364,7 +364,7 @@ is_hyperbolic_appproximation(::AbstractEquations) = Val{false}()
 If the equations are a hyperbolic approximation of another set of equations,
 return the equations of the limit system. Otherwise, return the input equations.
 
-See also [`is_hyperbolic_appproximation`](@ref).
+See also [`is_hyperbolic_appproximation`](@ref) and [`prim2phys`](@ref).
 
 !!! note "Implementation details"
     This function is mostly used for some internal dispatch. For example,
@@ -373,6 +373,29 @@ See also [`is_hyperbolic_appproximation`](@ref).
 """
 hyperbolic_approximation_limit(equations::AbstractEquations) = equations
 
+"""
+    prim2phys(q, equations)
+
+Convert the primitive variables `q` to the physically meaningful variables
+for a given set of `equations`. By default, this is the same as
+[`prim2prim`](@ref) for most equations. However, some equations like the
+[`HyperbolicSerreGreenNaghdiEquations1D`](@ref) return a reduced set of
+variables since they are a hyperbolic approximation of another set of
+equations (in this case the [`SerreGreenNaghdiEquations1D`](@ref)).
+
+See also [`is_hyperbolic_appproximation`](@ref) and
+[`hyperbolic_approximation_limit`](@ref).
+
+`q` is a vector type of the correct length `nvariables(equations)`.
+Notice the function doesn't include any error checks for the purpose of
+efficiency, so please make sure your input is correct.
+"""
+prim2phys(q, equations::AbstractEquations) = prim2prim(q, equations)
+
+function varnames(::typeof(prim2phys), equations::AbstractEquations)
+    return varnames(prim2prim, equations)
+end
+
 abstract type AbstractBathymetry end
 
 struct BathymetryFlat <: AbstractBathymetry end

src/equations/hyperbolic_serre_green_naghdi_1d.jl

@@ -107,6 +107,20 @@ function varnames(::typeof(prim2cons), ::HyperbolicSerreGreenNaghdiEquations1D)
     return ("h", "hv", "b", "hw", "hH")
 end
 
+"""
+    prim2phys(q, equations::HyperbolicSerreGreenNaghdiEquations1D)
+
+Return the physical variables ``\\eta, v, D`` used also by the
+[`SerreGreenNaghdiEquations1D`](@ref) from the main variables
+`q` for the [`HyperbolicSerreGreenNaghdiEquations1D`](@ref).
+"""
+function prim2phys(q, ::HyperbolicSerreGreenNaghdiEquations1D)
+    eta, v, D = q
+    return SVector(eta, v, D)
+end
+
+varnames(::typeof(prim2phys), ::HyperbolicSerreGreenNaghdiEquations1D) = ("η", "v", "D")
+
 is_hyperbolic_appproximation(::HyperbolicSerreGreenNaghdiEquations1D) = Val{true}()
 
 function hyperbolic_approximation_limit(equations::HyperbolicSerreGreenNaghdiEquations1D)

test/test_unit.jl

@@ -113,6 +113,7 @@ using SparseArrays: sparse, SparseMatrixCSC
             energy_total,
             prim2cons,
             prim2prim,
+            prim2phys,
         ]
         for conversion in conversion_functions
             @test DispersiveShallowWater.varnames(conversion, equations) isa Tuple
@@ -128,6 +129,7 @@ using SparseArrays: sparse, SparseMatrixCSC
         @test @inferred(still_water_surface(q, equations)) == 0.0
         @test isapprox(@inferred(energy_total(q, equations)), 8740.42)
         @test @inferred(energy_total(q, equations)) == @inferred(entropy(q, equations))
+        @test @inferred(prim2phys(q, equations)) == @inferred(prim2prim(q, equations))
 
         @testset "default implementation of energy_total_modified" begin
             initial_condition = initial_condition_convergence_test
@@ -162,6 +164,7 @@ using SparseArrays: sparse, SparseMatrixCSC
             energy_total,
             prim2cons,
             prim2prim,
+            prim2phys,
         ]
         for conversion in conversion_functions
             @test DispersiveShallowWater.varnames(conversion, equations) isa Tuple
@@ -177,6 +180,7 @@ using SparseArrays: sparse, SparseMatrixCSC
         @test @inferred(still_water_surface(q, equations)) == 0.0
         @test isapprox(@inferred(energy_total(q, equations)), 8740.42)
         @test @inferred(energy_total(q, equations)) == @inferred(entropy(q, equations))
+        @test @inferred(prim2phys(q, equations)) == @inferred(prim2prim(q, equations))
 
         @testset "default implementation of energy_total_modified" begin
             initial_condition = initial_condition_convergence_test
@@ -214,6 +218,7 @@ using SparseArrays: sparse, SparseMatrixCSC
             energy_total,
             prim2cons,
             prim2prim,
+            prim2phys,
             energy_total_modified,
             entropy_modified,
         ]
@@ -230,6 +235,7 @@ using SparseArrays: sparse, SparseMatrixCSC
         @test @inferred(discharge(q, equations)) == 88.0
         @test @inferred(still_water_surface(q, equations)) == 0.0
         @test isapprox(@inferred(energy_total(q, equations)), 8740.42)
+        @test @inferred(prim2phys(q, equations)) == @inferred(prim2prim(q, equations))
     end
 
     @testset "SerreGreenNaghdiEquations1D" begin
@@ -246,6 +252,7 @@ using SparseArrays: sparse, SparseMatrixCSC
             energy_total,
             prim2cons,
             prim2prim,
+            prim2phys,
         ]
         for conversion in conversion_functions
             @test DispersiveShallowWater.varnames(conversion, equations) isa Tuple
@@ -259,6 +266,7 @@ using SparseArrays: sparse, SparseMatrixCSC
         @test @inferred(momentum(q, equations)) == 84.0
         @test @inferred(discharge(q, equations)) == 84.0
         @test @inferred(still_water_surface(q, equations)) == 0.0
+        @test @inferred(prim2phys(q, equations)) == @inferred(prim2prim(q, equations))
     end
 
     @testset "HyperbolicSerreGreenNaghdiEquations1D" begin
@@ -276,6 +284,7 @@ using SparseArrays: sparse, SparseMatrixCSC
             energy_total,
             prim2cons,
             prim2prim,
+            prim2phys,
         ]
         for conversion in conversion_functions
             @test DispersiveShallowWater.varnames(conversion, equations) isa Tuple
@@ -289,6 +298,7 @@ using SparseArrays: sparse, SparseMatrixCSC
         @test @inferred(momentum(q, equations)) == 84.0
         @test @inferred(discharge(q, equations)) == 84.0
         @test @inferred(still_water_surface(q, equations)) == 0.0
+        @test @inferred(prim2phys(q, equations)) == [42.0, 2.0, 0.0]
     end
 
     @testset "AnalysisCallback" begin