Problem with integrals and averages if backflow??

Amit

Hi all--

I'm working on a problem which involves larynx simulation (i.e. heavy jetting, vorticity, and backflow). In particular, I am looking at dispersion effects of the larynx, and its effects on soluble gas deposition.

In doing so, I have found what I believe to be a fluent error. In post-processing my data, I am using the flow rate option in surface integrals (axisymmetric), and using such to calculate general flow rate and species specific flows (to find axisymmetric bulk concentrations). However, I believe the surface integral solver cannot appropriately solve a flow rate, if there is backflow.

For instance, on a converged solution, if I attempt to solve the integral of velocity through a surface (u dot n DA), in areas with backflow, I receive negative total flow rates, when by simple continuity, I know they should be positive.

Is there any way to solve a surface integral (or circumferential average, for that matter) with backflow without encountering this error?

--My thanks in advance, for all of your help