Correct boundary condition
Hi all,
I would like to perform this simulation using interFoam: 1) Inject a fluid in a certain domain (a box for example). My boundary conditon are (i guess standard BC for this case): alpha1 inlet fixedValue outlet inletOutlet U inlet fixedValue outlet zeroGradient p_rgh inlet zeroGradient outlet fixedValue left and right simmetryPlane 2) After a certain period of time i would like to stop the injection and let the system relaxes. Now, i'm quite confused about which boundary condition for alpha1 U and p_rgh is better to use at the inlet. I do not want to put simply a "wall" boundary condition, because i guess it is not physical so, in your opinion, which are the correct boundary conditions to have no fluid that comes in from the inlet? Then i have a second question. Is possibile with openFoam to switch (during the same simulation) from a boundary condition to an other? thanks a lot andrea |
1) why treating the inlet in relaxation time like a wall is not physical?
2) Are you familiar with groovyBC ? to implement ur boundary easily ;) |
Hi,
Perhaps you can extend the inlet section to have an inflow pipe/duct of reasonable length. Then during relaxation time, apply wall boundary condition in the pipe/duct which is equivalent to pipe/duct closing? Then there will be reasonable interaction between the domain of interest and the inlet section during relaxation. |
Hi, and thanks for the answer.
1)Because physically there isn't a wall (if you think for example an experiment). simply i want no flow that comes in. Put a "wall" boundary condition is the only choise i have? Something like: alpha1: zeroGradient U: fixedValue (0 0 0) p_rgh: zeroGradient or buoyantyPressure ?? 2)no, i'm not familiar with groovyBC, but if you are saying that you can easily implement a sort of "switching BC", i wiil give a look for sure. Best andrea |
Another idea could be to impose a "correct" pressure gradient between the inlet and the outlet and then to simulate until nothing moves (until there is no flow from the inlet). Is possibile with OF?
andrea |
Quote:
Quote:
|
Hi,
i found the "timeVaryingUniformFixedValue" BC, which is probably what i was looking for (it seems easier than groovyBC). I set alpha1 inlet inletOutlet, inletValue 1, value 1 outlet inletOutlet , inletValue 0, value 0 p_rgh inlet zeroGradient outlet fixedValue U inlet timeVaryingUniformFixedValue outlet zeroGradient and then i used the "ramp" file to switch between fixed velocity and zero velocity at the inlet. The inletOutlet BC at the inlet for alpha1 should ensure fixedValue =1 when the velocity is non-zero and zeroGradient when the velocity is zero. It seems to work. thanks again andrea |
All times are GMT -4. The time now is 05:40. |