CFD Online Discussion Forums

CFD Online Discussion Forums (
-   OpenFOAM (
-   -   Absurd results for blow down sim HELP plz! (

MatCFD May 31, 2011 09:30

Absurd results for blow down sim HELP plz!
1 Attachment(s)
Hi everybody,
i'm currently running a blow down transient simulation. It consists in a tank being vent out through a long slender pipe with several changes in cross section. The case is compressible since the involved fluid is N2.
I've modelled the case using pointwise as a 2d domain, so i have the following boundaries:
- 1 wall
- 1 outlet
- 2 empty lateral planes
- 1 simmetry plane
The initial conditions are:
- 24,6 bar pressure in the whole fluid domain
- 0,6 bar at the outlet
- no slip walls

Flow is supposed to be laminar for now.
I'm currently trying to solve it with rhoCentralFoam and 've already solved the case with sonicFoam. Every seems to be okay for both attempts except one thing: THE TANK TAKE LESS THAN 1 sec TO COMPLETELY VENT. This is abviously absurd (except in the case that the tank blows up); expected blow down time is 70-100 sec so there is something like a 10^2 factor in the time scale...
I've already checked the mesh and dimensions are ok (meters), so i'm really unable to find out the problem.
I've attached the case setup (without the mesh because of forum limitations in file size).
I will be very grateful to those who want to help me out to find out the issue. Thanks in advance!

All times are GMT -4. The time now is 22:55.