# 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

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 | 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 | 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 |

doublet_gradient_scheme | - | 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 |

Last modified 7mo ago