[lucasiervolino]

Hi,

I am conducting simulations on a 26ft SpeedBoat Hull in order to predict the planning phenomenon and the Total Drag Resistance (Shear + Pressure). Currently using DFBI + Overset Mesh in STAR-CCM+ for the setup. My mesh is around 1~1.5 Million cells for the whole VC.

After getting all the results and comparing them with Empirical Methods, like Savitsky, CFD simulation is reaching lower results. I wonder why, since Savitsky (at least the method I've used) does not account for Spray.

I was expecting it to be a little higher than Savitsky but then again I don't have (yet) the experimental values for this hull, to consistently compare them to CFD results. I may be looking at this in a wrong way so an outside perspective will certainly be an addition.

Pictures attached show the overset mesh, free surface and waves at 25knots.

Anyway, any thoughts/suggestions on the topic is welcome.

Thanks!

[lava12005]

Check the diffusion air-phase on the bottom of the hull? what about your y+?
Also remember that Savitsky's procedure is strictly for prismatic hull..