Pressure Losses
 

Good day, I have a big problem:)

I want to calculate the pressure losses in a divergent pipe; the start diameter is about 400 mm whereas at the end it is 500 mm. This increment takes place in about 1 meter of pipe lenght (no vortices are generated).

I run the 2D simulation in FLUENT v13 (velocity outflow: 1m/s; pressure inflow: 10 bar) and the residuals convergence is really good (more than 10^-6).

PROBLEM: I calculate the TOTAL PRESSURE with the function areaAve on the inlet section and on the outlet one. The incredible result is that the Total Pressure is increased (of about 250 Pa)!!! I think that it's not possible. It happens with a spatial discretisation of the second and of the third order, both with a k-eps and Reynolds stress model.

Do you have any suggestions??