Updates Magnetic model αr parameter

Changes the Magnetic model to directly accept a Float64 value for `αr` instead of a `Ref{Float64}`.

This simplifies the instantiation of the `Magnetic` struct and improves usability by removing the need to create a `Ref` object before passing the `αr` value.

Author: jmartfrut

src/PhysicalModels/MagneticModels.jl

@@ -9,8 +9,8 @@ struct Magnetic <: Magneto
   αr::Ref{Float64}
   χe::Float64
 
-function Magnetic(; μ0::Float64, αr::Ref{Float64}, χe::Float64=0.0)
-  new(μ0, αr, χe)
+function Magnetic(; μ0::Float64, αr::Float64, χe::Float64=0.0)
+  new(μ0, Ref(αr), χe)
 end
 function (obj::Magnetic)(Λ::Float64=1.0)
   μ, αr, χe = obj.μ, obj.αr, obj.χe

test/TestConstitutiveModels/PhysicalModelTests.jl

@@ -666,8 +666,7 @@ end
 @testset "Magnetic3D" begin
   ∇φ = VectorValue(1.0, 2.0, 3.0)
   a=40e-3 
-  ra=Ref(a)
-  modelID = Magnetic(μ0=1.2566e-6, αr=ra ,χe=0.0)
+  modelID = Magnetic(μ0=1.2566e-6, αr=a ,χe=0.0)
   Ψ, ∂Ψφ, ∂Ψφφ = modelID()
 
   Km=Kinematics(Magneto,Solid)
@@ -690,8 +689,7 @@ end
 @testset "Magnetic2D" begin
   ∇φ = VectorValue(1.0, 2.0)
   a=40e-3 
-  ra=Ref(a)
-  modelID = Magnetic(μ0=1.2566e-6, αr=ra ,χe=0.0)
+  modelID = Magnetic(μ0=1.2566e-6, αr=a ,χe=0.0)
   Ψ, ∂Ψφ, ∂Ψφφ = modelID()
 
   Km=Kinematics(Magneto,Solid)