Negative Room Pressure
 

Hi, I'm a student and in my Master’s degree final project i have to simulate a Negative Room Pressure.

In this case, I have 2 rooms:
- An anteroom, where I have to get -2.5 Pa
- The patient room --> -5 Pa

Both rooms are conected by a gap around the door. Both rooms have air difussers (with a ventilation system that removes more exhaust air from the room than air is allowed into the room) and gaps around other doors and windows (boundary condition = pressure inlet 0).

The main problem is that i never get a convergence. I tried to separated the room in three bodies:
- Anteroom
- Patient Room
- Gap door. I made a structured mesh in this body, because i thought the problems were here, but them remain.

So I have no idea what is wrong. I simulate with standard k-e, althought I have tried other methods.

I wonder if the problem is that is no possible to maintain in contact two different pressure, or something like that.

On this aspect, I would like to ask for your help.

Really? Pressure is never negative (physically)

When i said negative pressure, i referred to gauge pressure, sorry.

So, do you use gauge pressure for simulation? Because in simulation, I always use absolute pressure. Also, check operating condition pressure. And let me know your simulation in details (Boundary condition, mesh, etc).