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-   -   Study of wingtip vortices (http://www.cfd-online.com/Forums/star-ccm/71783-study-wingtip-vortices.html)

 rory_the_king January 14, 2010 12:03

Study of wingtip vortices

Hello!I'm Lorenzo and I live in Vicenza (Italy).
I have to study the wingtip vortices of a flow over the Naca 0012 half-wing rounded wing tip.
The chord of the airfoil is about 1.2 m.
What are the three dimensions of the wind tunnel?
Can someone help me?
Bye Bye
Lorenzo

It really depends upon what you want to simulate. If you want to reproduce some physical experiment, it will be better to take the same dimensions which were in the actual wind tunnel. If you want to simulate your wing in free unbounded stream... Well, actually in this case you'll have to make some parametric study to check the influence of boundary locations. But usually it's something like this: at least 10 chords away up, down, upstream and to the side from the wing tip, and at least 20 chords downstream. You can also check materials of AIAA Drag Prediction Workshops for recommended domain size.

 rory_the_king March 1, 2010 17:43

I need to reproduce an experimental in wind tunnel!!!
I have a question:how can I export a profile of pressure and temperature of a plane?
I have to reduce the wind tunnel to analyze the wake!!!so I have to import the profile of pressure and temperature of new two planes (the new inlet and outlet).

example:

first wind tunnel (along x axes) from -12m to +36 m
section inlet and outlet 12m x 12m

second wind tunnel from -3m to +12 m
section new inlet and outlet 1m (high) and 1,5m (span)

I have to export the profile of pressure, temperature, velocity ecc ecc
of the first simulation and wind tunnel in the second!!!
How can I do?
Thanks of all!
Lorenzo - vertigo1981
sorry for some errors in my text!!!

You can specify your boundary conditions with tables. Unfortunately this issue is not covered in tutorials, but you can start from Command reference - there are examples of different possible tables formats in the TBREAD command description.

 rory_the_king March 2, 2010 06:06

where can I find the thread?
thanks
lore

how can I cut a plane from a derived part?
if I have an inlet boundary. how can I cut a plane smaller?
thanks
lore

Sorry, I've forgot we were talking about STAR-CCM+ :) Then no tables, you'll have to write a user function in Java, which will apply boundary conditions (probably reading some data from external file first).

 rory_the_king March 2, 2010 07:12

There is a function tables in star ccm+!
The only my problem is how can I cut a plane of "my" dimension!!!
With a threshold I can solve the problem!!!
Bye bye
lore

 isaac1326 September 11, 2013 22:11

Hi,
I`m facing some difficulty in running a simulation on a wing(3d airfoil) in Star-CCM+. The experimental data isnt matching with my CFD results. I mean, the results are wayoff and my mesh is really good, because I couldnt find any sharp edges on my Cl vs Iteration graph. The face quality of my mesh is also above 0.5. And, Iv tried playing with density and dynamic viscosity coefficient, but I couldnt get the results.
Any help would be really appreciated!

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