SimScale CAE Forum

Negative Pressure Isolation Ward not giving realistic results

Here is my project

I’m unable to get my velocities to reach realistic values, I’ve had results on the order of 1e+23. I’ve reviewed the boundary conditions multiple times so I know that they are good. I’ve tried compressible and incompressible simulations. I was able to get realistic velocities and somewhat realistic pressures in the case of a single room but the h value was all over the place in the convergence plot. Expanding this setup to the half ward case was too much computationally and I only got to ~20s, with a 1 s timestep, after 13 core hours. Does anyone have any insight or tips for me?

I saw that you made some improvements already!

A good advice is to start with steady state first and move on to transient once you have established a proper setup.

General recommendations from my colleague:

  1. Extend inlets/outlets
  2. He is using flow conditions at inlet and outlet, the open face can then be bit bigger if possible

Let us know if that helped!

Jousef

Hi Jousef,

I ended up extending the domain for the pressure inlet and this did help me.

My issue with h being all over the place got fixed as well. I had been selecting eConst in the material section but was failing to save that change. Now on my convergence plot it shows e instead of h and the residual decays as I would expect.

Just commenting this in case anyone comes by looking for a fix to a similar issue, The goal was to decrease the pressure in the room by a significant amount so I had to use Compressible flow, incompressible was not giving realistic velocities for my set up. I was also having issues where two rooms separated by the air under a door were at about 20 Pa different from each other but removing the door fixed this issue. In future simulations if I need the door I will be increasing the width of the space under the door to attempt to fix that.