the static pressure at one outlet is negative?
 

Hi, my friends, I simulated the pressure distribution in a geometry with pushed air in it. But I got a negative pressure at one outlet. That means the static pressure at this outlet is lower than the static pressure at reference point (101325 Pa). But I guess the pressure at this outlet should be higher than 101325. Because air is pushed from the bottom to the top of the geometry. Maybe the inlet is too close to the outlet. Then I extended the outlet to 5 times of the distance from the original position. And the static pressure are positive .But the mass flow rate at this outlet is positive， which is different with other two outlets.
My questions are: 1. why is the mass flow rate is positive at this outlet? 2. Is the pressure at the original outlet reliable after I extended it to a far distance?

I am so forwarding to your help! Thanks so so much!

Regards,

Rong

The original geometry is like this: Attachment 24418

the original geometry

the static pressure at inlet and outlets

the geometry after extended outlets

the mass flow rate at inlets and outlets after extended the outlets

the static pressure at inlets and outlets after extended outlets

the mass flow rate at inlets and outlets in the original geometry

Does anybody understand my problem? Please! Thanks a lot!