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Davy October 17, 2006 20:37

How to model suction flow in an airfoil in Fluent
Hi all,

I'm an undergrad in aerospace engineering , researching for a project of mine. I am having problem finding information online as to how to model an airfoil (wing)with tiny holes in part of the wing in Gambit.

Moreover, I am uncertain if fluent is capable of modeling a suction flow through this hole at supersonice air flow, I was told by my instructor to research online to see if anyone has done anything similar but have no sucess in doing so.

In addition to that, i was questioned by my instructor whether or not if the flow can magically disapper after they are 'sucked' in to the airfoil..(in real life situation, the flow being sucked in through the wing can be sent to a propulsion and exit through the exhaust, but programming all this in Fluent would almost be impossible for me)

It would be highly appreciated if any one of the bright minds here can help me out with this. Thank you

Ryan October 18, 2006 01:57

Re: How to model suction flow in an airfoil in Flu
Yes it is possible.

The flow will dissappear once it reaches this boundary.

Iam not sure if you have details of the pressure in this boundary or it will be wise to set the pressure as zero and check what it is doin?.

Good Luck!!



Davy October 18, 2006 18:49

Re: How to model suction flow in an airfoil in Flu
Thanks Ryan, I talked to another professor of mine today He suggested that it will be better for me to 'program' the location of those suction holes as 'outflow' boundary with a mass flow going into those 'holes'

I just need to know if this is 100% do-able for a beginner in fluent in a 3 to 4 months span.

Jason October 19, 2006 08:31

Re: How to model suction flow in an airfoil in Flu
Do you actually know the mass flow through each of the holes, or do you know the suction pressure being applied?

Be very careful about "outflow" here... the outflow BC in Fluent has some major assumptions built into it and I would not recommend using it in your circumstance. Check chapter 7.10 in the Users guide for assumptions in the outflow BC (if you don't have access, do a google search... there's a couple universities that have it available online).

I recommend the pressure outlet for these holes. If you know the actual mass flow through each hole, you can set the target mass flow rate (if you define all the holes as a single BC, I believe the target mass flow rate is the total of all of the faces so that you can have some faces pulling more air and some pulling less).

Good luck, Jason

Vincent October 23, 2006 03:56

Re: How to model suction flow in an airfoil in Flu
I think it is only possible to simulate a relatively large "gap" in the wing. If you want to simulate something like boundary layer suction, Fluent is not able to do the job.

I'm working on BLS; Fluent cannot calculate the influence of a small suction velocity on the boundary layer profile. Fluent takes the velocity normal to a wall equal to zero by definition, therefore suction through a wall is not possible. If you use a different BC, such as velocity/pressure outlet, Fluent will not calculate a boundary layer at all.

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