Outflow Boundary Condition

J. Weiler

In order to find the pressure drop through a 180 degree bend, I have chosen to use a mass flow inlet and an outflow (for which the pressure is unknown). The Fluent help files suggested using the Outflow boundary condition when pressure is a desired result. When I run the simulation for two mass flow rates (0.02 and 0.05 kg/s) I get zero static pressure at the outlet where the flow is fully developed, and my pressure drop is just the new pressure value at the inlet. However, when I run it with a mass flow rate of 0.10 kg/s I get 2 Pa at the fully developed outlet. I can still check for pressure drop between the inlet and the outlet, but I am just wondering why in some cases it yields zero static and in other cases it doesn't. I have extended the length of my outlet pipe to 40x the hyd. diameter, so the flow is fully developed. I welcome any advice. Thanks Justin