[amwitt]

Hello,

I am trying to simulate flow through a gate using Fluent's VOF model. The bottom portion of the domain is water and the top portion is air. Flow coming in through the velocity inlet passes under a gate and travels downstream. I'd like to match the water elevation downstream as close as possible to the conditions at the actual site. To do this, I've made a downstream section the same height as the water elevation and patched it with water. I've set a pressure outlet with constant backflow volume fraction = 1 as a downstream BC. There is a downstream section of air above the water, and I've also set that as a pressure outlet for air. The solution blows up quickly at the interface between those two pressure outlets, diverging within a few iterations. Any advice on what may be happening here? I've tried changing the pressure outlet to calculate from neighboring cells, and I've tried initializing both the air and water domains with a downstream velocity but that doesn't seem to work.

Thanks in advance.