Drag Coefficient Parameterization

Question

Hi,

I'm trying to change the boundary conditions at the bottom (right now it is set to Turbulent BBL). How is AEM3D computing Drag when we set, for instance, the option "free-slip sides, drag bottom"? I see a value of 0.0035 (drag_btm_cd) so I was wondering if that is a Manning Coefficient or some type of bed roughness estimation.

Thanks in advance.

Answer 1

Hi Rafael,

When TBBL is set the drag coefficient is used to create TKE in mixing routines and mixes momentum and scalars up from the bottom.

For DRAG BCs the drag coefficient is used to create stress term in the free surface equation, of the form -CdU|U|

Chris