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-   -   External Aero Questions (https://www.cfd-online.com/Forums/fluent/37952-external-aero-questions.html)

 Alan September 20, 2005 15:16

External Aero Questions

Hi All,

Hope any of you guys can help me with some simple questions.

1 - What span length Fluent assumes while reporting drag or lift values in 2D analysis for airfoils?

2- What is the best setup for external aerodynamics analysis. I am after setting solution parameters like turbulence intensity and length etc etc.

Alan

 Riaan September 20, 2005 18:00

Re: External Aero Questions

1) Infinite span as per 2D convention 2) External Aero - set Turbulence model - the turb intensity, length etc. I just leave as default. Probably good guess unless you are modelling low-turbulence flow like in wind tunnels.

 Alan September 21, 2005 10:46

Re: External Aero Questions

Riaan,

Thanks for the reply. If the span is infinite how can the force value be a finite figure? If you think about it, if we keep on increasing the span the force value keeps on increasing. Well, this may be different in 2D analysis, however I dont know how?

Luckily I am modelling low turbulence flow inside a wind tunnel - If you have any guide lines then it would be greatly appreciated.

Many Thanks,

Alan.

 Jason September 21, 2005 13:04

Re: External Aero Questions

The span is set using the "depth" value in the reference values (Report->Reference Values). The default value is 1 meter. You should also be careful to set your other reference values (you can let Fluent calculate the fluid values by using the "compute from" drop down box and selecting your inlet BC and then manually entering your reference area and length) or your coefficients will be almost useless.

Hope this helps, and good luck, Jason

 Alan September 23, 2005 13:58

Re: External Aero Questions

Thanks a million Jason. I will have a go at it and see how things go!

Thanks once again.

Alan

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