Mesh and Surface Dictionaries

Mesh Dict

Here is a list of the keys and default values of the mesh_dict, which is used to generate a mesh, e.g. mesh = generate_mesh(mesh_dict).

Mesh definition

Key

Default value

Units

Description

num_x

3

Number of chordwise vertices. Needs to be 2 or an odd number.

num_y

5

Number of spanwise vertices for the entire wing. When symmetry = True, the numbe of vertices for a half wing will be ``(num_y + 1) / 2.

span

10.0

m

Full wingspan, even for symmetric cases.

root_chord

1.0

m

Root chord length.

span_cos_spacing

0

Spanwise cosine spacing. 0 for uniform spanwise panels, 1 for cosine-spaced panels.

chord_cos_spacing

0

Chordwise cosine spacing.

wing_type

“rect”

Initial shape of the wing. "rect" or "CRM".

symmetry

True

If true, OAS models half of the wing reflected across the plane y = 0.

offset

np.array([0, 0, 0])

m

Coordinates to offset the surface from its default location.

num_twist_cp

2

Number of twist control points. Only relevant when wing_type = "CRM".

Surface Dict

Here is a non-exclusive list of the surface dict keys. The surface dict will be provided to Groups, including Geometry, AeroPoint, and AerostructGeometry.

Surface definition

Key

Example value

Units

Description

name

“wing”

Name of the surface.

symmetry

True or False

If true, OAS models half of the wing reflected across the plane y = 0.

S_ref_type

“wetted” or “projected”

How we compute the wing reference area.

mesh

3D ndarray

m

x, y, z coordinates of the mesh vertices, can be created by generate_mesh.

twist_cp

np.array([0, 5])

deg

B-spline control points for twist distribution. Array convention is [wing tip, ..., root] in symmetry cases, and [tip, ..., root, ... tip] when symmetry = False.

Aerodynamics definitions

Key

Example value

Units

Description

CL0

0.0

Lift coefficient of the surface at 0 angle of attack.

CD0

0.015

Drag coefficient of the surface at 0 angle of attack.

with_viscous

True or False

If true, compute viscous drag

with_wave

True or False

If true, compute wage drag

groundplane

True or False

If true, compute ground effect.

k_lam

0.05

Airfoil property for viscous drag calculation. Percentage of chord with lanimar flow.

t_over_c_cp

np.array([0.12, 0.12])

B-spline control points for airfoil thickness-over-chord ratio

c_max_t

0.303

Chordwise nondimensional location of the maximum airfoil thickness.

Structure definitions

Key

Example value

Units

Description

fem_model_type

“tube” or “wingbox”

Structure model.

E

73.1e9

Pa

Young’s modulus

G

27.5e9

Pa

Shear modulus

yield

420.0e6 / 1.5

Pa

Allowable yield stress including the safety factor.

mrho

2.78e3

kg/m^3

Material density

fem_origin

0.35

Normalized chordwise location of the spar

wing_weight_ratio

2.0

Ratio of the total wing weight (including non-structural components) to the wing structural weight.

exact_failure_constraint

True or False

If False, we use KS function to aggregate the stress constraint.

struct_weight_relief

True or False

Set True to add the weight of the structure to the loads on the structure.

distributed_fuel_weight

True or False

Set True to distribute the fuel weight across the entire wing.

fuel_density

803.0

kg/m^3

Fuel density only needed if the fuel-in-wing volume constraint is used)

Wf_reserve

15000.0

kg

Reserve fuel mass

n_point_masses

1

Number of point masses in the system (for example, engine)

Structure parameterization for tubular spar

Key

Example value

Units

Description

thickness_cp

np.array([0.01, 0.02])

m

B-spline control point of the tube thickness distribution.

radius_cp

np.array([0.1, 0.2])

m

B-spline control point of the tube radius distribution.

Structure parameterization for wingbox

Key

Example value

Units

Description

spar_thickness_cp

np.array([0.004, 0.01])

m

Control point of spar thickness distribution.

skin_thickness_cp

np.array([0.005, 0.02])

m

Control point of skin thickness distribution.

original_wingbox _airfoil_t_over_c

0.12

Thickness-over-chord ratio of airfoil provided for the wingbox cross-section.

data_x_upper

1D ndarray

x coordinates of the wingbox cross-section’s upper surface for an airfoil with the chord scaled to 1.

data_y_upper

1D ndarray

y coordinates of the wingbox cross-section’s upper surface

data_x_lower

1D ndarray

x coordinates of the wingbox cross-section’s lower surface

data_y_lower

1D ndarray

y coordinates of the wingbox cross-section’s lower surface