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 = 140
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
wake_alignment = 0
wake_angle = 0
json_output = 0
paraview_output = 0
tecplot_output = 0
restart_from_checkpoint = 0
neighbour_tolerance = 1e-6
tip_panels =
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
Dimension
Description
Default value
c_ref
$L$
Reference chord, used for non-dimensionalisation of the aerodynamic coefficients
1
b_ref
$L$
Reference span, used for non-dimensionalisation of the aerodynamic coefficients
1
S_ref
$L^2$
Reference area, used for non-dimensionalisation of the aerodynamic coefficients
1
x_cg, y_cg, z_cg
$L$
Location of the centre of gravity
0
trailing_edge_angle
-
Edges sharper than the trailing edge angle in degrees are identified as trailing edges
140
p_ref
$M/(L{\cdot}T^2)$
Reference pressure
101325
rho_ref
$M/L^3$
Reference density
1.225
mu_ref
$M/(L{\cdot}T)$
Reference dynamic viscosity
1.789e-5
norm_V_ref
$L/T$
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
$1/T$
Roll, pitch, and yaw rates in degrees/sec
0
dt
$T$
Time step
1
N_timesteps
-
Number of timesteps
1
wake_alignment, wake_angle
-
Specifies how the wake aligns with respect to the trailing edges
0
json_output, paraview_output, tecplot_output
-
Enables or disables JSON, ParaView, and Tecplot output
0
restart_from_checkpoint
-
Instructs the solver to restart the solution from a checkpoint
0