[gianlu.it]

Hello,

I'm using OpenFOAM-v2012 to run multiple simulations in calm water for planning hulls between 8 to 20 meters at full scale.

Having the necessity to run several analysis with a very limited pre-processing time budget, I'm using a universal set-up with fairly robust correctors on the PIMPLE solver:

nOuterCorrectors 2;
nCorrectors 3;
nNonOrthogonalCorrectors 2;

In all the simulations there are 2 DOF (pitch and heave) controlled by the dynamicMesh, inertia matrix is quite close to reality.

The analysis are always converging but there is a substantial bottleneck on the computing time due to the high number of correctors.

I started few tests reducing the quantity of correctors but the analysis is diverging as soon as they are decreased. From a physical point of view, the boat starts with a given trim angle and after few seconds (depending on the specific case, i.e. speed, weight, inertia, hull geometry) the hull reacts by partially emerging from the water. Once the hull slams back to the free surface the analysis diverges and stop. This is probably due to the high pressure generated during slamming which requires the current "big" amount of correctors.

I would like to create a time controlled ramp (better if quadratic) on the forces applied to the hull thus minimizing the risk of slamming. From what I read in this forum there should be a built-in command which can be implemented to the dictionary but I wasn't able to find any clear definition or reference. I would be very grateful if anyone could provide me any guidance on the implementation.

Thank you!