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-   -   [ICEM] setting B.C & FF shape for high A.O.A. (http://www.cfd-online.com/Forums/ansys-meshing/121751-setting-b-c-ff-shape-high-o.html)

 jyh3134 August 5, 2013 00:40

setting B.C & FF shape for high A.O.A.

5 Attachment(s)
Hi guys,
I recently have generated a hexa mesh of a fairing(see attached pics).

The mesh has ractangular far field(boundary surface of computational domain).

And set B.C to Velocity inlet, pressure outlet, symmetry (See attached pics.)

The blocking was OK, and simulation at 0 deg of A.O.A was also OK.
(see attached pics of B.C, residuals)

but I need to simulate with this configuration from 0 to 90 deg of A.O.As.

I have no idea that how to define B.C when A.O.A is very high.(e.g. 45 deg, 60 deg, 80, 90 deg..)

The freestream is 8m/s, so pressure-based solver is needed.

perhaps I can....
1. rotate geometry of faring, and blocking again.
2. change solver to density-based, and use pressure far-field B.C
3. change shape of FF surfaces.
4. Now is good, go on ....

How do you think? I need your help.

Best@Regards

 diamondx August 5, 2013 01:55

Don't touch the mesh, have you done the naca tutorial in fluent !? just change the velocity component x and y ie, when AOA is 0, x=1 and y=0 ...

 jyh3134 August 5, 2013 02:20

Thanks

Quote:
 Originally Posted by diamondx (Post 443808) Don't touch the mesh, have you done the naca tutorial in fluent !? just change the velocity component x and y ie, when AOA is 0, x=1 and y=0 ...
I already know set angle of fresstream using vector. (e.g. at a.o.a. 15 deg,
x : cos15, y :sin15)

But when increasing a.o.a, reversed flow error occus at sudden a.o.a.

Now I'm trying that 0~45 deg : present B.C,
45~90 deg : change B.C of top surface to pressure outlet, and other to velocity inlet.

 Far August 5, 2013 07:44

Couple of things.

1. Your mesh is very good. However at TE you should go for C type grid and collapse blocking. Do you have access to "Hexa blocking around cone" on ansys customer portal?

2. At 45 AOA you domain shape should be hemisphere at inlet and cylinder at outlet.

3. At 45 AOA the wake will be different. Therefore you need much denser in that region. So maybe Quarter O-grid is better option for your case. Or at least you should align mesh with flow.

 jyh3134 August 6, 2013 09:24

thanks far

1 Attachment(s)
1. I used y-blocks to capture sharp tail likes 'your' old post about "Rectangular Enclosure 3d wedge". (see attached pic) :)
And I wonder where ansys customer portal is.. I want to you to tell me.

2. sorry I can't understand.

Just in case, I uploaded prj files.

https://www.dropbox.com/s/r76m14aj8bwemn1/question.zip

3. O.K. I wil, thanks.

Best&Regards

Quote:
 Originally Posted by Far (Post 443877) Couple of things. 1. Your mesh is very good. However at TE you should go for C type grid and collapse blocking. Do you have access to "Hexa blocking around cone" on ansys customer portal? 2. At 45 AOA you domain shape should be hemisphere at inlet and cylinder at outlet. 3. At 45 AOA the wake will be different. Therefore you need much denser in that region. So maybe Quarter O-grid is better option for your case. Or at least you should align mesh with flow.

 Far August 7, 2013 03:23

Ok. Angle is not too sharp. You can go with current blocking at trailing edge.

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