[aristotaufiq]

Hi Guys,

I've been using OpenFOAM for the last couple of month, the solver that has been the most useful for me is pimpleDyMFoam (just pimpleFoam for the latest OpenFOAM v6). This is because that I usually simulate store release from an aircraft.

The Problem that I encounter now is that, currently, I need to simulate a drop of several uncoupled bodies at the same time. This is not much of a problem now that rigidBodyMotion motion solver (without the "sixDof" mind you) is available. I wanted to give an initial acceleration and velocity value the the different bodies. Is there any keyword I can insert to the dynamicMeshDict that will allow me to do this?

I could not seem to get much resource and documentation regarding this new implementation of rigid body motion. It seems that we really have to dive into the source code in order to understand it more. However, I currently can't do that as my C++ level is just that bad.

I currently use OF5, but may as well be upgrading to the latest OF

Best Regards,
Aristo

[zkdkeen]

Hi Aristo, have you solved it? I am facing similar problems as you did currently.

The ref below points out that the key word "qDot" can be used to set up intial velocity, but it seems not working.

http://www.tfd.chalmers.se/~hani/kur...dyDynamics.pdf

[Petires]

Hi
I have also encountered this problem recently. I am using OpenFOAM v2006 so check if it works in your case. To set initial velocity in your 0 or 0.orig folder create folder:


uniform


and in this folder create file:


rigidBodyMotionState


And its content should be:


/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: v2006 |
| \\ / A nd | Website: www.openfoam.com |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
FoamFile
{
version 2.0;
format ascii;
class dictionary;
location "0.01/uniform";
object rigidBodyMotionState;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

q 8 ( 0 0 0 0 0 0 0 0 );

qDot 8 ( 0 0 0 0 0 0 10 0 );

qDdot 8 ( 0 0 0 0 0 0 0 0 );

t 0;

deltaT 0;


// ************************************************** *********************** //



In the file above q is position with regard to the specific joint, qDot is velocity and qDdot is acceleration. 8 stands for number of degrees of freedom and values are ordered as linear and then angular for each body in order x,y,z. In my case first body has 6 DoF, second has one DoF and its angular x, for which I set velocity 10 and third has also one degree of freedom.
Hope it will be helpful
Petires

[VigneshSP]

@Petires

Thank you very much, It worked.