Mass flow "outlet" BC reverses flow after 20 iterations
 

I need to control the mass flow coming out of my outlet. It's essentially a cylindrical tank with a pipe at the end. There is not inlet, just the outlet with some gravity to account for. The tank starts out 3/4 full of water, the rest is air.

When I use the mass flow inlet with a negative mass flow value, the flow out of my outlet ends of up reversing, going into the tank, after about 20 iterations at 0.005s. I tried using a flow-split outlet because it seemed to remedy the problem, the only issue is, is that one the water gets low enough, it starts pulling air through the pipe way too fast and the simulation blows up and the mass flow out of the outlet goes crazy.

I was reading that I need to use the extruder mesh to properly set the outlet so that it can handle the mass flow "outlet" boundary condition.

https://www.cfd-online.com/Forums/st...ow-outlet.html

If so, how do I do this? I wasn't able to find any directions on how to setup the extruder mesh let alone apply it to the outlet's boundary condition.

Nevermind, please ignore. I figured it out.

Devs please delete if necessary.