How to calculate oscillating roll of 2D body (with variable amplitude and omega)
 

Dear colleagues. I have to calculate oscillating roll of semi-submerged 2D body in water (OpenFOAM 2.3.1). If I use the constant amplitude and omega of oscillations the view of the pointMotionU is
FoamFile
{
version 2.0;
format ascii;
class pointVectorField;
object pointMotionU;
}

dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{

form
{
type angularOscillatingVelocity;
axis (0 0 1);
origin (600 0 0);
angle0 0;
amplitude 0.2;
omega 1;
value uniform (0 0 0);
}
…
But for this variant the force acting on the body in the beginning of the calculations is very big.
I would like to start from the oscillations with SMALL amplitude and during two or three periods increase this amplitude to necessary value.
I suppose that it is possible to include in pointMotionU Table with two columns
Time, Angle.
If it is possible my problem will be solved. But I do not know how to change pointMotionU and include Table “angle vs time”.
Thank you very much in advance for your help.
Alexander Lavrov, Lisbon, IST.