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	$L$	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	150
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
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, 1, 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	""
trefftz_plane_analysis	-	Performs trefftz analysis at the trefftz plane to evaluate lift and drag	0
symmetry	-	Enables symmetry across the x-y plane. The solutions 2x faster and the memory requirements are 2x lower.	0