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trixi-framework
GitHub Repository: trixi-framework/Trixi.jl
 Path: blob/main/src/equations/equations_parabolic.jl
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# specify transformation of conservative variables prior to taking gradients.

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# specialize this function to compute gradients e.g., of primitive variables instead of conservative

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gradient_variable_transformation(::AbstractEquationsParabolic) = cons2cons

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# By default, the gradients are taken with respect to the conservative variables.

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# this is reflected by the type parameter `GradientVariablesConservative` in the abstract

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# type `AbstractEquationsParabolic{NDIMS, NVARS, GradientVariablesConservative}`.

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struct GradientVariablesConservative end

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# Linear scalar diffusion for use in linear scalar advection-diffusion problems

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abstract type AbstractLaplaceDiffusion{NDIMS, NVARS} <:

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              AbstractEquationsParabolic{NDIMS, NVARS, GradientVariablesConservative} end

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"""

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    have_constant_diffusivity(::AbstractLaplaceDiffusion)

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# Returns

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- `True()`

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Used in diffusive CFL condition computation (see [`StepsizeCallback`](@ref)) to indicate that the

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diffusivity is constant in space and that [`max_diffusivity`](@ref) needs **not** to be re-computed

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at every node in every element.

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Also employed in [`linear_structure`](@ref) and [`linear_structure_parabolic`](@ref) to check

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if the diffusion term is linear in the variables/constant.

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"""

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@inline have_constant_diffusivity(::AbstractLaplaceDiffusion) = True()

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"""

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    max_diffusivity(equations_parabolic::AbstractLaplaceDiffusion)

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# Returns

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- `equations_parabolic.diffusivity`

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Returns isotropic diffusion coefficient for use in diffusive CFL condition computation,

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see [`StepsizeCallback`](@ref).

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"""

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@inline function max_diffusivity(equations_parabolic::AbstractLaplaceDiffusion)

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    return equations_parabolic.diffusivity

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end

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include("laplace_diffusion_1d.jl")

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include("laplace_diffusion_2d.jl")

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include("laplace_diffusion_3d.jl")

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include("laplace_diffusion_entropy_variables.jl")

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include("laplace_diffusion_entropy_variables_1d.jl")

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include("laplace_diffusion_entropy_variables_2d.jl")

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include("laplace_diffusion_entropy_variables_3d.jl")

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# Compressible Navier-Stokes equations

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abstract type AbstractCompressibleNavierStokesDiffusion{NDIMS, NVARS, GradientVariables} <:

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              AbstractEquationsParabolic{NDIMS, NVARS, GradientVariables} end

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include("compressible_navier_stokes.jl")

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include("compressible_navier_stokes_1d.jl")

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include("compressible_navier_stokes_2d.jl")

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include("compressible_navier_stokes_3d.jl")

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