GfsOutputSolidForce

From Gerris

GfsOutputSolidForce computes the total force and moments exerted by the fluid on the embedded solid boundaries (defined using GfsSolid).

The moments are expressed with the origin of the domain as reference.

The first time GfsOutputSolidForce is called, a description of the different fields is written:

# 1: T (2,3,4): Pressure force (5,6,7): Viscous force (8,9,10): Pressure moment \
(11,12,13): Viscous moment

where the numbers are the column indices and the three components of each term correspond to the x, y and z axis respectively.

The syntax in parameter files is:

[ GfsOutput ] [ GfsFunction ]

where the GfsFunction is optional. If it is present, the force/moment integral calculation is weighted by this function. This can be used for example to compute the force acting on only a fraction of the domain.

Examples

• Air-water flow around a Series 60 cargo ship

    OutputSolidForce { istart = 1 istep = 1 } f

• B\'enard--von K\'arm\'an vortex street behind a cylinder translating in a fluid at rest

  OutputSolidForce { istep = 1 } forces.dat