[openfoam_user]

Dear OF-users,

I am trying to compute VOF simulations around ships using the rasInterFoam solver.

I have used the main settings of E. Patterson (wigley hull) with another geometry.

But the case is crashing after a few iterations, maybe due to the quality of the mesh.

I use ICEMCFD Hexa for grid generation.

I was wondering what other grid softwares are used by the other users of OF (for complex geometries like cars, aircrafts and ships) ?

All comments about grid softwares and how to set-up VOF simulations around ships are welcome.

Regards,

Stephane.

[eugene]

The general purpose meshing tool shipped with OPENFOAM 1.5 is snappyHexMesh.

[openfoam_user]

Hi Eugene,

do you know a tutorial for snappyHexMesh with complex geometry ?

Stephane

[anders]

Hello Stephane,

I'm working on the same type of computations. I also experienced that the solver crashed with the wigley tutorial settings on a realistic hull. I had to change the scheme to more upwind weighting. I got convergence with the following settings.



divSchemes
{
div(rho*phi,U) Gauss upwind;
div(phi,gamma) Gauss upwind;
div(phirb,gamma) Gauss interfaceCompression;
div(phi,k) Gauss upwind;
div(phi,epsilon) Gauss upwind;
div(phi,R) Gauss upwind;
div(R) Gauss linear;
div(phi,nuTilda) Gauss upwind;

div((nuEff*dev(grad(U).T()))) Gauss linear;
}


laplacianSchemes
{
default Gauss linear corrected limited 0.5;
}


I have not yet compared the computed drag with my own CFD solver, so I don't know if it gives to mush diffusion to the solution.

Anders

[openfoam_user]

Hi Anders,

Thanks. I will try your settings and give you a feedback asap.

Which software do you use for mesh generation ?

Have you tried snappyHexMesh ?

Stephane.

[anders]

Stephane,

I use an in-house gridgenerator where I have developed an efficient parametric template for ship hulls. However I have not yet succeeded in converting meshes from our format to the OpenFOAM grid format (work in progress...).

The only ship hull I have yet computed in OpenFOAM was generated by the StarCCM+ software.

I have not yet had time to look in to the snappyHexMesh utility.

Anders

[vinz]

Hi Stephane,

On our side we use GridPro to create meshes around ships and planes.
We created a converter from GridPro to OpenFOAM which is available on the forum and works for a large band of cases (still needs some code implementation for periodic boundary conditions).
I did not make computations on ships but some clients did.
If you want some other information, do not hesitate to contact me.

Hope that helped.

Regards

[openfoam_user]

Dear Anders, dear Vincent,

GridPro are among the best grid softwares with ICEM and Gridgen.

I am a new user of OpenFOAM. And maybe beginning with free surface computations is not the simplest thing.

I have done meshes around ship with ICEM hexa. The quality seems good, but the computation crashes after some iterations.

I have download the mesh of E. Patterson (wigley hull) and his settings. The case runs well. Just changing the geometry make the case crashes after less than 10 iterations.

Stephane.

[vinz]

Hi Stephane,

I don't know if your geometry is very confidential.
But if it's not, i can give it a look and try to do a mesh so you can try a different mesh generator and see if it's coming from that or not.
If you want, just send me an email, so we can arrange everything.

Vincent