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-   -   Help needed for school project! (http://www.cfd-online.com/Forums/fluent/108891-help-needed-school-project.html)

cfduser123 November 4, 2012 03:21

Help needed for school project!
 
Hi guys, I have just started dabbling with the basics, and my professor is already demanding a decent analysis of a project Im doing. Basically, my group is engaged by an external company to help them with their problem, and my school has allocated a prof to us who is unable to transfer any fluent knowledge to us. So we are on our own. What i have now is a step file from the company, can you help me with this? Its a chamber with existing suction outlets attached to it, and we must study the air flow inside it.

Help is deeply (and urgently) appreciated!

Far November 4, 2012 05:41

state your problem in detail and show some pics. obviously first step in the problem solving is to get the right geometry and meshing.

cfduser123 November 4, 2012 08:56

1 Attachment(s)
I have the geometry with me since I can conveniently check out the dimensions using Solidworks on the step file. Trouble is, the step file contains too many volumes which have errors when I do meshing in gambit. Attached is an external view of the chamber, the internal parts are much more than this.

I am expected to produce an analysis in 3 days' time. Is it possible?

Far November 4, 2012 09:00

Yes and no. It depends how you simplify your problem and understand it. Meshing the simplified model should not take much time and also you must know the boundary conditions. If you have required info then this can be done in few days. Otherwise NO

cfduser123 November 4, 2012 09:28

I only know the flow rate at the suction outlets. What other boundary conditions do i have to know/assume? May i know if "meshing the simplified model" means excluding the volumes when I do the meshing? I have 263 volumes in the step file and I do not know how to modify it for a simpler model.

ghost82 November 4, 2012 14:52

Quote:

Originally Posted by cfduser123 (Post 390155)
I only know the flow rate at the suction outlets. What other boundary conditions do i have to know/assume? May i know if "meshing the simplified model" means excluding the volumes when I do the meshing? I have 263 volumes in the step file and I do not know how to modify it for a simpler model.

Hi,
I suggest to simplfy your model (don't import the step file, make a new model in gambit) if you want results in some days.
You can create parallelepipeds for chambers; I think you could not take into account the volumes of tubes; you can create circles at the wall of your chamber and apply there boundary conditions.
Then, if you have object inside the chamber, simplify them, subtract to your volume other parallelepipeds/cylinders, which represents objects.

Take into account leakage: otherwise, if you neglet them your mass flow rate at outlet will be your mass flow rate at inlet; so, for example, you can set mass flow rate for inlet and pressure outlet for outlet (if the chamber communicate with external ambient set the pressure to atmospheric).
Since I think your pressure drop are not too much, you can simplify your model and set a constant air density, so to have an incompressible model.

All the bests,

Daniele


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