Merge pull request #294 from OpenSourceAWE/agent/BeyondTheSim.jl-17

Fit the contour generate_airfoils is handed, not a second wrap of it

Author: 1-Bart-1

CHANGELOG.md

@@ -29,6 +29,12 @@
 
 ### Fixed
 
+- `generate_airfoils` fits the contour it is handed rather than shrink-wrapping it a
+  second time. Both adapters wrap before they call, with the `wrap_method` their
+  settings name, so the second wrap discarded that setting and degenerated the Kulfan
+  fit: on the SK100's 45 mesh sections nine came out with `.dat` coordinates at 1e2 to
+  1e4 instead of 0..1, and any consumer mapping the mesh onto a structure rejected the
+  geometry.
 - The `NONLIN` solver backtracks along each Newton step instead of always taking
   it whole, so it converges past stall where the full step used to cycle: on the
   `test/solver/solver_test_wing.yaml` wing at 26.6° it stopped 3.6% below `LOOP`'s

src/airfoil_aero/geometry_gen.jl

@@ -42,7 +42,8 @@ function generate_airfoils(airfoils, output_dir::String;
             alphas = deg2rad.(collect(Float64, alpha_range))
             deltas = isnothing(delta_range) ? [0.0] :
                 deg2rad.(collect(Float64, delta_range))
-            aero, sols = generate_airfoil_aero(aero_solver, af.x_fit, af.y_fit;
+            aero, sols = generate_airfoil_aero(aero_solver,
+                fit_kulfan_parameters(af.x_fit, af.y_fit, LeastSquaresFit());
                 alpha_range=alphas, delta_range=deltas,
                 reynolds_number=Float64(Re), crease_frac)
             clvals = collect(sol.cl for sol in sols[1])

test/airfoil_aero/test_airfoil_aero.jl

@@ -271,3 +271,20 @@ end
     cp(joinpath(weights_dir, "nn-medium.npz"), joinpath(partial, "nn-medium.npz"))
     @test_throws ErrorException load_neuralfoil_model("medium"; weights_dir=partial)
 end
+
+@testset "generate_airfoils fits the wrapped contour it is handed" begin
+    x_raw, y_raw = read_dat_coords(joinpath(@__DIR__, "data", "test_airfoil.dat"))
+    x_fit, y_fit = shrink_wrap(x_raw, y_raw, ShrinkWrap(clearance=0.0))
+    _, fitted_y = kulfan_to_coordinates(
+        fit_kulfan_parameters(x_fit, y_fit, LeastSquaresFit()))
+    out = mktempdir()
+    _, ok = generate_airfoils([(; id=1, x_fit, y_fit, x_raw, y_raw)], out;
+        Re=5e5, alpha_range=-2:2:2,
+        aero_solver=NeuralFoilSolver(model_size="medium"), verbose=false)
+    @test ok == [1]
+    _, written_y = read_dat_coords(joinpath(out, "airfoils", "1.dat"))
+    # A second shrink wrap inflates the section by its own clearance, 0.006, which is
+    # three orders of magnitude above the resampling error this tolerance allows.
+    @test maximum(abs, collect(extrema(written_y)) .-
+                       collect(extrema(fitted_y))) < 1e-4
+end