External Force Dynamic Link Libraries

ANSYS AQWA has the ability to include a user-defined external force algorithm via a dynamic link library (DLL). A DLL can be created to calculate a force based on time, position and/or velocity of a structure. Example interfaces are provided for C or FORTRAN™, but any programming language that can produce a DLL can be employed. An added mass matrix can be computed at each time step to simulate inertia forces. The calculation can be controlled by a set of up to 100 integer parameters and 100 real parameters that may be input and then passed to the external force routine.

This facility can be used to model:

  • Dynamic positioning system
  • Steering system
  • Towing force provided by a tug
  • Damping system with unusual characteristics
  • Suction force between two ships close together, or between a ship and the sea bed
  • Fluid transfer between vessels
  • Calculated energy extracted from a wave-power device