godotmisogi / aerofuse.jl

A toolbox meant for aircraft design analyses.

I'm an unguided missile.

aerofuse.jl's Issues

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Strange floating point precision error

I was trying to calculate the lift coefficient of a NACA4412 airfoil and I encountered the following error:

foil = naca4((4,4,1,2), 70)
uniform = Uniform2D(1.0, 4.0)
system = solve_case(
    foil,
    uniform
)
cl = lift_coefficient(system)

ERROR: BoundsError: attempt to access 69-element extrapolate(interpolate((view(::Matrix{Float64}, :, 1),), ::Vector{Float64}, Gridded(Linear())), Throw()) with element type Float64 at index [-0.000268420185446816]
Stacktrace:
  [1] throw_boundserror(A::Interpolations.Extrapolation{Float64, 1, Interpolations.GriddedInterpolation{Float64, 1, Vector{Float64}, Interpolations.Gridded{Interpolations.Linear{Interpolations.Throw{Interpolations.OnGrid}}}, Tuple{SubArray{Float64, 1, Matrix{Float64}, Tuple{Base.Slice{Base.OneTo{Int64}}, Int64}, true}}}, Interpolations.Gridded{Interpolations.Linear{Interpolations.Throw{Interpolations.OnGrid}}}, Interpolations.Throw{Nothing}}, I::Tuple{Float64})
    @ Base ./abstractarray.jl:691
  [2] inbounds_index
    @ ~/.julia/packages/Interpolations/Sxe87/src/extrapolation/extrapolation.jl:111 [inlined]
  [3] inbounds_position
    @ ~/.julia/packages/Interpolations/Sxe87/src/extrapolation/extrapolation.jl:102 [inlined]
  [4] Extrapolation
    @ ~/.julia/packages/Interpolations/Sxe87/src/extrapolation/extrapolation.jl:48 [inlined]
  [5] _broadcast_getindex_evalf
    @ ./broadcast.jl:670 [inlined]
  [6] _broadcast_getindex
    @ ./broadcast.jl:643 [inlined]
  [7] getindex
    @ ./broadcast.jl:597 [inlined]
  [8] macro expansion
    @ ./broadcast.jl:961 [inlined]
  [9] macro expansion
    @ ./simdloop.jl:77 [inlined]
 [10] copyto!
    @ ./broadcast.jl:960 [inlined]
 [11] copyto!
    @ ./broadcast.jl:913 [inlined]
 [12] copy
    @ ./broadcast.jl:885 [inlined]
 [13] materialize
    @ ./broadcast.jl:860 [inlined]
 [14] interpolate(foil::Foil{Float64}, xs::Vector{Float64})
    @ AeroFuse.AircraftGeometry ~/.julia/packages/AeroFuse/dwOGa/src/Geometry/AircraftGeometry/Foils/foil.jl:76
 [15] cosine_interpolation
    @ ~/.julia/packages/AeroFuse/dwOGa/src/Geometry/AircraftGeometry/Foils/foil.jl:125 [inlined]
 [16] make_panels(foil::Foil{Float64}, n::Int64)
    @ AeroFuse.AircraftGeometry ~/.julia/packages/AeroFuse/dwOGa/src/Geometry/AircraftGeometry/Foils/foil.jl:149
 [17] #solve_case#7
    @ ~/.julia/packages/AeroFuse/dwOGa/src/Aerodynamics/Cases/foil_cases.jl:10 [inlined]
 [18] solve_case(foil::Foil{Float64}, freestream::Uniform2D{Float64})
    @ AeroFuse ~/.julia/packages/AeroFuse/dwOGa/src/Aerodynamics/Cases/foil_cases.jl:10
 [19] top-level scope
    @ REPL[4]:1

Strangely, this error only occurs for specific values of n:

foil = naca4((4,4,1,2), n) # fails if n = 69, 70, 72, 73 but works if n = 67, 68, 71, 74

Looking through the code, I suspect that when it is calculating the cosine interpolation,

AeroFuse.jl/src/Tools/MathTools.jl

Line 141 in 5726868

cosine_spacing(x_center, diameter, n :: Integer = 40) = @. x_center + (diameter / 2) * cos(-π:π/(n-1):0)

AeroFuse.jl/src/Geometry/AircraftGeometry/Foils/foil.jl

Lines 123 to 125 in a242e25

	x_circ = cosine_spacing((x_min + x_max) / 2, x_max - x_min, n)
	interpolate(foil, x_circ)

the resulting minima of the interpolated values can sometimes be lower than the minima of the input values, causing interpolate to fail due to it being out of bounds.
Maybe change it to the following to avoid the loss of precision?

cosine_spacing(x_start, x_end, n :: Integer = 40) = @. max(x_start + (x_end - x_start) * (cos(-π:π/(n-1):0)+1)/2, x_end)
# ...
x_circ = cosine_spacing(x_min, x_max, n)

Thanks!

Incorrect results in doublet-source panel method example case.

When I ran the case codes, I got that:
julia> begin airfoil = naca4((2,4,1,2)); foil = Foil(airfoil); V, α = 1.0, 3.0; uniform = Uniform2D(V, α); cl, cls, cms, cps, panels = solve_case(foil, uniform; num_panels = 80); end;cl -0.06478979281472284

as the result of NACA2412 is around 0.608250
# result from XFoil when alpha = 3.0 deg and re = 1e5 and mach = 0.0 is 0.608250 ? where is the error?

Importing Coordinates file and assigning new header name do not work

Describe the bug
The read_foil() function fail to assign new header name to the airfoil

To Reproduce
Steps to reproduce the behavior:

1. Go to 'read_airfoil()'
2. Set 'header = true'
3. Assign a value 'name = airfoil_test'
4. See error

Expected behavior
I expected airfoil.name to give the newly assigned value.

Screenshots

Desktop (please complete the following information):

• OS: macOs Monterey 12.2.1
• Browser: Safari
• Version: 12.2.1