Add lip factor to neighbor list cells

src/SPHCellList.jl

@@ -18,7 +18,7 @@ using ..OpenExternalPrograms
 using ..SPHKernels
 using ..SPHViscosityModels
 using ..SPHDensityDiffusionModels
-using ..SPHNeighborList: BuildNeighborCellLists!, ComputeCellNeighborCounts, ComputeCellParticleCounts, ConstructStencil, ExtractCells!, MapFloor, UpdateNeighbors!, UpdateΔx!
+using ..SPHNeighborList: BuildNeighborCellLists!, ComputeCellNeighborCounts, ComputeCellParticleCounts, ConstructStencil, DefaultNeighborLipFactor, ExtractCells!, MapFloor, NeighborListInverseCutOff, UpdateNeighbors!, UpdateΔx!
 
 using StaticArrays
 using StructArrays: StructArray, foreachfield
@@ -297,7 +297,7 @@ using LinearAlgebra
         return nothing
     end
 
-    f(SimKernel, GhostPoint) = CartesianIndex(map(x -> MapFloor(x, SimKernel.H⁻¹), Tuple(GhostPoint)))
+    f(SimKernel, GhostPoint; LipFactor = DefaultNeighborLipFactor) = CartesianIndex(map(x -> MapFloor(x, NeighborListInverseCutOff(SimKernel.H⁻¹, typeof(SimKernel.H⁻¹)(LipFactor))), Tuple(GhostPoint)))
     function NeighborLoopMDBC!(SimKernel,
                                SimMetaData::SimulationMetaData{Dimensions, FloatType, SMode, KMode, BMode, LMode},
                                SimConstants, ParticleRanges, CellDict, Position,
@@ -724,7 +724,8 @@ using LinearAlgebra
                 @timeit SimMetaData.HourGlass "01 Calculate IndexCounter"  begin
 
                     SimMetaData.Δx = UpdateΔx!(SimMetaData.Δx, Positionₙ⁺, SimParticles.Position)
-                    ShouldRebuild = SimMetaData.Δx >= SimKernel.h
+                    NeighborListLipFactor = FloatType(DefaultNeighborLipFactor)
+                    ShouldRebuild = SimMetaData.Δx >= SimKernel.h * NeighborListLipFactor
 
                     # println("Δx: ", Δx, "h: ", SimKernel.h," dt: ", SimMetaData.CurrentTimeStep, " Iteration: ", SimMetaData.Iteration, " TotalTime: ", SimMetaData.TotalTime, " OutputIterationCounter: ", SimMetaData.OutputIterationCounter)
 
@@ -735,7 +736,7 @@ using LinearAlgebra
                     # Remove if statement logic if you want to update each iteration
                     # if mod(SimMetaData.Iteration, ceil(Int, SimKernel.H / (SimConstants.c₀ * dt * (1/SimConstants.CFL)) )) == 0 || SimMetaData.Iteration == 1
                     if ShouldRebuild
-                        @timeit SimMetaData.HourGlass "01a Actual Calculate IndexCounter" SimMetaData.IndexCounter = UpdateNeighbors!(SimParticles, SimKernel.H⁻¹, SortingScratchSpace,  ParticleRanges, UniqueCells, CellDict)
+                        @timeit SimMetaData.HourGlass "01a Actual Calculate IndexCounter" SimMetaData.IndexCounter = UpdateNeighbors!(SimParticles, SimKernel.H⁻¹, SortingScratchSpace,  ParticleRanges, UniqueCells, CellDict; LipFactor = NeighborListLipFactor)
                         SimMetaData.Δx    = zero(eltype(dρdtI))
                         UniqueCellsView   = view(UniqueCells, 1:SimMetaData.IndexCounter)
                         BuildNeighborCellLists!(NeighborCellLists, FullStencil, UniqueCellsView, ParticleRanges, CellDict)

src/SPHNeighborList.jl

@@ -1,9 +1,16 @@
 module SPHNeighborList
 
-export ConstructStencil, ExtractCells!, UpdateNeighbors!, BuildNeighborCellLists!, ComputeCellParticleCounts, ComputeCellNeighborCounts, UpdateΔx!
+export ConstructStencil, ExtractCells!, UpdateNeighbors!, BuildNeighborCellLists!, ComputeCellParticleCounts, ComputeCellNeighborCounts, UpdateΔx!, NeighborListInverseCutOff
 
 using StaticArrays
 
+const DefaultNeighborLipFactor = 1.2
+
+@inline function NeighborListInverseCutOff(InverseCutOff::T, LipFactor::T = T(DefaultNeighborLipFactor)) where {T<:Real}
+    @assert LipFactor > zero(T) "Neighbor list lip factor must be positive"
+    return InverseCutOff / LipFactor
+end
+
 function ConstructStencil(V::Val{d}) where d
     return CartesianIndices(ntuple(_ -> -1:1, V))
 end
@@ -42,7 +49,8 @@ Extracts the cells for each particle based on their positions and the inverse cu
 
 # Arguments
 - `Particles`: The particles whose cells are to be extracted.
-- `::Val{InverseCutOff}`: The inverse cutoff value used for cell extraction.
+- `InverseCutOff`: The inverse cutoff value used for cell extraction.
+- `LipFactor`: Scaling factor to expand cell sizes around their centers.
 
 # Returns
 - `nothing`: This function modifies the `Particles` in place.
@@ -55,9 +63,10 @@ Extracts the cells for each particle based on their positions and the inverse cu
     Int(sign(X)) * unsafe_trunc(Int, muladd(abs(X), InverseCutOff, 0.5))
 end
 
-@inline function ExtractCells!(Particles, InverseCutOff)
+@inline function ExtractCells!(Particles, InverseCutOff, LipFactor = DefaultNeighborLipFactor)
+    EffectiveInverseCutOff = NeighborListInverseCutOff(InverseCutOff, typeof(InverseCutOff)(LipFactor))
     @inbounds @simd ivdep for Index ∈ eachindex(Particles.Cells)
-        Particles.Cells[Index] = CartesianIndex(map(X -> MapFloor(X, InverseCutOff), Tuple(Particles.Position[Index])))
+        Particles.Cells[Index] = CartesianIndex(map(X -> MapFloor(X, EffectiveInverseCutOff), Tuple(Particles.Position[Index])))
     end
     return nothing
 end
@@ -71,13 +80,15 @@ Updates the neighbor list and sorts particles by their cell indices.
 - `SortingScratchSpace`: Scratch space for sorting.
 - `ParticleRanges`: Array to store the ranges of particles in each cell.
 - `UniqueCells`: Array to store the unique cells.
+- `LipFactor`: Scaling factor to expand cell sizes around their centers.
 
 # Returns
 - `IndexCounter`: The number of unique cells identified.
 """
 function UpdateNeighbors!(Particles, InverseCutOff, SortingScratchSpace,
-                          ParticleRanges, UniqueCells, CellDict)
-    ExtractCells!(Particles, InverseCutOff)
+                          ParticleRanges, UniqueCells, CellDict;
+                          LipFactor = DefaultNeighborLipFactor)
+    ExtractCells!(Particles, InverseCutOff, LipFactor)
 
     sort!(Particles, by = p -> p.Cells; scratch=SortingScratchSpace)
     Cells = @views Particles.Cells