[m.nichols19]

I am attempting to execute a simple test case using the icoFoam solver and have encountered a presumably easy problem that I cannot figure out. The mesh of the test case is a cylinder with a L-W ratio of 10:1. The inlet and outlet are on opposite faces of the cylinder. The inlet is given a relatively small initial velocity.

What should the boundary field conditions of the outlet be? I have attempted setting the velocity as zero and zeroGradient, and pressure as zeroGradient; however, those conditions return the following error:

Continuity error cannot be removed by adjusting the outflow.
Please check the velocity boundary conditions and/or run potentialFoam to initialise the outflow.

The test case only runs when the boundary field condition of the outlet is given a velocity greater than zero.

best regards,
Matt