Anti-Ventilation Method
 

Hi,
I'm simulating a planing hull by ccm+ at about Fn=1.2.
By the volume fraction of water I found a little quantity of air below the hull.
This phenomenon induces also wrong trim and resistance value.

I heard about an anti-ventilation method used to correct the drag value deducting, from some cells (only the cells that have less of 50% of water), a small percentage of air.

I try this method but I found some difficult to apply it.
I write a custom field function called "zone" that compute the volume from which deduct air. ($WallDistance > .003)?0 : (($VolumeFractionWater < .5)?0 : 1)

Then I write a function called "airsource" by which is possible deduct air: $VolumeFractionAIR*$zone / -.03

The problem is: I'm not able to compute the new drag considering that deduction.
Could you help me?

Thanks