Varying Body Force (Acceleration)

The body force, defined through acceleration in units of [m/s2] can be varied over time using an input file.

This file needs to be in the following form:
time Bodyforce_x Bodyforce_y Bodyforce_z
As an example, we use:
0 0 0 -9.81
1 0 0 -5.6
3 2.1 4.3 -7.2

Note that there are no headers of any sort in the file.

The difference between input time values does not need be constant. The value of the gravity is interpolated linearly at each time step of the simulation between the closest greater and lesser time values of the input file.

To load the file, one line is necessary in the config file, inside the Domain parameters section:
bodyforcefile inputFileName.txt    

The data of this file are read one time at the beginning of the simulation. The start time in the prescribed motion file cannot be smaller than the initial time of the simulation.

No damping function is used.