Lower resistance force with finer mesh?

Arman

Hi,

I computed the resistance of a ship using CFD. When I refine the grid, the resistance becomes smaller (which is closer to the experiment). My question is, is this a general thing? If it is, why? If it isn't, what is the general thing you can expect by refining the grid. FYI, I used k-omega turbulence model without transient motion (steady state), which should be close to reality as the Froude number is low enough to generate wave and the Reynolds number is high enough to suppress any transient motion such as vortex shedding.

Best regards, -Arman-