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Velocity space

In kinetic methods, variables are also discretized in velocity space. Information in velocity space are separately stored in AbstractPsData, and are organized as following.

Origin must be on a grid corner

The velocity grid is set up from the quadrature range and vs_trees_num of the Configure. It carries an implicit requirement that the origin v = 0 lie on a grid corner (never inside a cell); see check_vs_setting and the note on the Configuration page. The requirement is validated when the configuration is built.

KitAMR.VsData — Type
mutable struct VsData{DIM, NDF} <: AbstractVsData{DIM, NDF}

  • vs_num::Int64: Number of velocity cells.

  • level::Vector{Int8}: Refinement level of velocity cells.

  • weight::Vector{Float64}: Quadrature weight of velocity cells.

  • midpoint::Matrix{Float64}: Coordinates of centers of velocity cells in velocity space.

  • df::Matrix{Float64}: Discretized distribution function.

  • sdf::Array{Float64, 3}: Spatial gradients (df/dx) of distribution function.

  • flux::Matrix{Float64}: Numerical flux of distribution function.

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KitAMR.GhostVsData — Type
mutable struct GhostVsData{DIM, NDF} <: AbstractVsData{DIM, NDF}

  • vs_num::Int64

  • level::Vector{Int8}

  • weight::Vector{Float64}

  • midpoint::Matrix{Float64}

  • df::Matrix{Float64}

  • sdf::Array{Float64, 3}

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KitAMR.FaceVsData — Type
struct FaceVsData{DIM, NDF, W<:AbstractVector{Float64}, M<:AbstractMatrix{Float64}, V<:AbstractVector{Float64}, D<:AbstractMatrix{Float64}, S<:(AbstractArray{Float64})}

Information of the velocity space corresponding to the face during the calculation of numerical flux.

  • heavi::Vector{Bool}: Upwinding flags. Upwinding velocities are set to true.

  • weight::AbstractVector{Float64}

  • midpoint::AbstractMatrix{Float64}

  • vn::AbstractVector{Float64}: Normal component of velocities across the face.

  • df::AbstractMatrix{Float64}

  • sdf::AbstractArray{Float64}

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KitAMR.CuttedVelocityCells — Type
mutable struct CuttedVelocityCells

Structure for cut cell in velocity space used in immersed boundaries.

  • indices::Vector{Int64}: Indices of cut cells in SolidNeighbor's VsData.

  • weight::Vector{Float64}: Quadrature weight of velocity cells. Specially, the weight of cut cells is set to 0.

  • gas_dfs::Matrix{Float64}: Distribution function of gas part corresponding to velocity at the center of cut cells.

  • solid_dfs::Matrix{Float64}: Distribution function of solid part corresponding to velocity at the center of cut cells.

  • gas_weights::Vector{Float64}: Areas of gas part in cut cells.

  • solid_weights::Vector{Float64}: Areas of solid part in cut cells.

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