Define enum PanelDistribution

Author: ufechner7

data/vsm_settings.yaml

@@ -1,11 +1,19 @@
 Model:
     VSM: Vortex Step Method
     LLT: Lifting Line Theory
+
+PanelDistribution:
+   LINEAR:             Linear distribution
+   COSINE:             Cosine distribution
+   COSINE_VAN_GARREL:  van Garrel cosine distribution
+   SPLIT_PROVIDED:     Split provided sections
+   UNCHANGED:          Keep original sections
+
 wings:
     - name: main_wing
       n_panels: 40
       n_groups: 40
-      spanwise_panel_distribution: "LINEAR"
+      spanwise_panel_distribution: LINEAR
       spanwise_direction: [0.0, 1.0, 0.0]
       remove_nan: true
     - name: tail

src/settings.jl

@@ -5,7 +5,7 @@ data = YAML.load_file(joinpath("data", filename))
     name::String = "main_wing"
     n_panels::Int64 = 40
     n_groups::Int64 = 40 
-    spanwise_panel_distribution::String = "LINEAR"
+    spanwise_panel_distribution::PanelDistribution = LINEAR
     spanwise_direction::MVec3 = [0.0, 1.0, 0.0]
     remove_nan = true
 end