The configuration file

The .conf file contains different options which specify the problem that APM will solve. The contents of an example .conf file are shown below:

c_ref = 1 
b_ref = 1
S_ref = 1
x_cg = 0 
y_cg = 0 
z_cg = 0
trailing_edge_angle = 150
p_ref = 101325
rho_ref = 1.225
mu_ref = 1.789e-5
norm_V_ref = 1
M_ref = 0
alpha = 0 
beta = 0 
p = 0
q = 0
r = 0
dt = 1
N_timesteps = 1
restart_from_checkpoint = 0
wake_alignment = 0
wake_angle = 0
wake_rollup = 1
output_frequency = 1
paraview_output = 1
tecplot_output = 0
json_output = 0
extended_output = 0
doublet_gradient_scheme = 0
neighbour_tolerance = 1e-6
trefftz_plane_analysis = 0
tip_panels =   
symmetry = 0

The values in the above .conf file are in SI units - m, kg, s. You can use different units as long as they are consistent across the .conf file.

Refer to the table below for a detailed description of each option.

Option

Dimensionality

Description

Default value

c_ref

Reference chord, used for non-dimensionalisation of the aerodynamic coefficients

1

b_ref

Reference span, used for non-dimensionalisation of the aerodynamic coefficients

1

S_ref

Reference area, used for non-dimensionalisation of the aerodynamic coefficients

1

x_cg, y_cg, z_cg

Location of the centre of gravity

0

trailing_edge_angle

-

Edges sharper than the trailing edge angle in degrees are identified as trailing edges

150

p_ref

Reference pressure

101325

rho_ref

Reference density

1.225

mu_ref

Reference dynamic viscosity

1.789e-5

norm_V_ref

Reference freestream speed

1

M_ref

-

Reference Mach number (used for compressibility corrections)

0

alpha, beta

-

Angle of attack and angle of sideslip with respect to the freestream in degrees

0

p, q, r

Roll, pitch, and yaw rates in degrees/sec

0

dt

Time step

1

N_timesteps

-

Number of timesteps

1

restart_from_checkpoint

-

Instructs the solver to restart the solution from a checkpoint

0

wake_alignment, wake_angle

-

Specifies how the wake aligns with respect to the trailing edges

0

wake_rollup

-

If disabled the induced velocities from the body on the wake and on the wake iteslf wont be calculated. The wake will be translated with the reference freestream speed.

1

json_output, paraview_output, tecplot_output

-

Enables or disables JSON, ParaView, and Tecplot output

0

extended_output

-

Appends force and moment vector for each panel in the Paraview and Tecplot output files

0

doublet_gradient_scheme

-

Instructs the solver how to calculate the doublet gradient

0

neighbour_tolerance

-

Specifies the neighbour tolerance criteria

1e-6

tip_panels

-

Instructs the solver to label specific panels as type 6

Empty

symmetry

-

Enables symmetry across the x-y plane. The solutions 2x faster and the memory requirements are 2x lower.

0

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