Dear users. I solve a flow-field on the bridge with wind speed of 10m/s. The flow goes left to right so,i set the B.C velocity inlet on the left and pressure outlet on the right. On the top and bottom, I used symmetry B.C. That B.C system worked. However,at this time,I want to consider free stream on the top and bottom not symmetry. I already did this with pressure-far fied but some error message about ideal gas and energy equation poped up. How can i define far-field region for free stream in incompressibe flow. please reply me.

Thanks in advance.

Hi, pressure-far field BC's implemented in Fluent are for compressible flows and cannot be used in the framework of an incompressible flow model as (I guess) you are working with. Try to locate your top/bottom boundaries of the grid quite far from the bridge and use velocity-inlet BC's there...in this case you're assuming the flow is undisturbed there, as it should be if the boundaries are enough far from the body...

P.S. On the right side also "outflow" BC's could be used in your model (that is, zero flow gradient..)