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[ICEM] Tandem Airfoil Meshing Problems

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Old   May 12, 2011, 17:05
Default Tandem Airfoil Meshing Problems
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Ryne
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Hello, I am trying to mesh airfoils and a tandem arrangement, one behind the other. I am struggling heavily to come up with a blocking strategy for my domain that properly resolves the boundary layers around my airfoils. The main problem that I am having is with respect to the leading edge of the trailing airfoil. I cannot seem to come up with a blocking scheme that easily allows for both a good mesh and fully resolved boundary layer around both airfoils. My latest attempts are shown in the pictures below. The limitations of this method is that significant smoothing must occur to even have mesh that runs in FLUENT, and also if the boundary layer is too fine, the smoothing process distorts and messes up the mesh on the leading edge of the trailing airfoil.

I am here for help and advice, if I wasn't clear enough on anything just ask.

Thanks!!
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File Type: jpg After Smoothing.jpg (61.8 KB, 38 views)
File Type: jpg Before Smothing.jpg (56.1 KB, 33 views)
File Type: jpg Blocking.jpg (38.0 KB, 34 views)
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Old   May 13, 2011, 00:12
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Helo Ryne,

You have to create O or a C-topology around the aerfoil to better capture the boundary layer and to have better quality cells. It will also give you better control ouer the no of nodes inside the boundary layer. You can find in tutorials how to create a O grid, there is a video for a 2D airfoil in Youtube which might be helpfull for you.

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Old   May 13, 2011, 04:05
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I think it would be much easier and faster to create and attach software-defined boundary layers (e.g. boundary layer command in GAMBIT) to the foils and unstructured mesh in the rest of domain, rather than creating your own bl in a structured mesh. In this way you can put any number of airfoils in rbitrary arrangements without extra work.
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Old   May 13, 2011, 15:11
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I have watched the tutorials and have used an O grid type structure throughout which captures the leading airfoil very well. The issue is that the second (trailing) airfoil does not have the nice semi-circle in front of it to make the nice C type structure.

I no longer have access to GAMBIT, so I'm using ICEM. Do you know if there is a similar type of BL creating tool in ICEM that would allow me to build BL and unstructure the rest?
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Old   May 13, 2011, 17:58
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Quote:
Originally Posted by Rhyno466 View Post
I no longer have access to GAMBIT, so I'm using ICEM. Do you know if there is a similar type of BL creating tool in ICEM that would allow me to build BL and unstructure the rest?
Ryne,

I have never worked with ICEM, so I am not of the great adviser for this, but I have just searched "blayer" command in ICEM "help" and found a section called "Blayer 2d" with examples of unstructured meshes attached to boundary layers. You might try to look these examples in the "help" manual.

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Old   May 14, 2011, 00:11
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Hello ryne, If you want to create automatic bl then you can go for a unstructured mesh where you can create bl just by click. But you are doing a blocking approach which is very different from gambit, it is purely a mapped mesh. Your model is relatively simpler one and will not be difficult to create a al with an ogrid. It will be good if you can upload images of what problems you are facing or if possible you can upload your geometry and blocking file i will have a look and modify it and send you back.
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Old   May 15, 2011, 15:48
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Thanks for the help! I have attached a picture of the bad smoothing that occurs when I resolve the boundary layer the way I would like to. I have also provided a link to the latest files that I have been using. For some reason, the current file (unsmoothed) has uncovered faces so I cannot run it as is in Fluent. I have been though many different blocking schemes, and this current one is the closest to yielding the desired results.

Any help for getting a good mesh with a well resolved boundary layer of both airfoils would be appreciated. Please ask any questions that you may have and I will do my best to provide the clarifying answers!

Thanks

https://sites.google.com/site/rynedr...edirects=0&d=1
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Old   May 16, 2011, 02:40
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Hello Ryne,

I have done slight modifications to your blocking, find the attachement. I have created C grids over the airfoils. you can do the bunching arrangement as you desire to have.

regards
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File Type: zip modified_tandem_airfoil.zip (15.5 KB, 17 views)
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Old   May 16, 2011, 10:41
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Thanks so much Jeevan!! This is exactly what I was looking for! I am now hoping that you could possibly provide some insight on how you accomplished this, specifically, what you did with my blocking scheme to get it as it is now? I am also interested in how you created the C grid around the second airfoil. Again, I am relatively new (2 months) to ICEM so some of this stuff is rather new to me.

Thanks
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