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-   -   [ICEM] 2d hemisphere in wind tunnel (https://www.cfd-online.com/Forums/ansys-meshing/102816-2d-hemisphere-wind-tunnel.html)

 aftertime June 3, 2012 12:27

2d hemisphere in wind tunnel

i just wanna calculate drag of a hemisphere in wind tunnel .i had a problem in first step when i tried generate mesh file in icemi . i dont know which far field is better . i tried some but i had problem in aspect ratio . if some one can help me it would be great . i must add that wind hit the flat side of hemisphere in tunnel . sry for my bad english

 Far June 3, 2012 15:20

attach geometry file

 aftertime June 4, 2012 08:09

1 Attachment(s)
i attached my icem file with a random farfield that i dont know if its good or not . tnx for your help

 Far June 4, 2012 09:25

2d case..... Shouldn't it be 3d?

 aftertime June 4, 2012 10:18

our teacher did it for a sphere with a bigger sphere for far field and as far as i know we do it in 2d and the axis line make it a perfect sphere . for my case i did same thing with hemisphere . for a sphere mesh had good quality but for hemishpere the flat line causes some aspect ratio problem .

 Far June 4, 2012 10:33

My favourite post

I like this post very much http://www.cfd-online.com/Forums/ans...sh-fluent.html
It is classical work using ICEM.

 aftertime June 4, 2012 11:23

the topic you linked is great but i feel my issue is very simple and primary

the project our teacher wanna us to do is a simple one like the one he did in class (because we are beginner and amature )
here is a link for the one he did for sphere . he did it in 5 min and asked us do it for different geometry like mine(hemisphere)
and after that exported it to fluent . and i know what to do there for drag and ...
( i just wanna know how should i take my far field for a good blocking and after that meshing ) again sry for bad english ;)

tnx a lot for your attention and time .

 Far June 4, 2012 12:12

1 Attachment(s)
Ok . Done in five minutes (I wasn't counting :p.)

http://img403.imageshack.us/img403/2716/12531369.png

http://img818.imageshack.us/img818/646/30150213.png

 Far June 4, 2012 12:26

 diamondx June 4, 2012 12:26

2 Attachment(s)
here is how i changed the far field, of curse you need refinement so you can capture boundary layer. i suppose you know how to play with it. i'm sure there is a better blocking strategy

 aftertime June 4, 2012 12:33

tnx man you helped alot . now i must look at it and figure it out how u did that ( im amature as u know :D)
thank you very very much

 Far June 4, 2012 12:40

Quote:
 i must add that wind hit the flat side of hemisphere in tunnel
From left to right? Any angle of attack?

 aftertime June 5, 2012 07:00

yes From left to right and no angle . btw you split it to 9 blocks ?

 Far June 5, 2012 07:56

I just made three half ogirds. one for body, one for boundary layer and one for outer layer

 aftertime June 5, 2012 11:47

I worked on what you suggested and here is what i did ( i should thank diamondx too ) . i think it has lots of problem . i exported it to fluent and when i checked quality the Minimum Orthogonal Quality was 6.62394e-01 . i dont know how i can enhance the quality .
and something else . i need check the drag coefficient from experiment with what i calculate . do you have any idea where i can find one? i search a little for it but i didnt find any .

* sry that i upload my file in different place . i just wanna some expert (like you ;) )see it with detail and help me correct mine

 Far June 5, 2012 12:31

0.6 is very good quality. Minimum needed is 0.01 by fluent. Meshing is good, but you have very fine mesh in far field..

 reza45000 June 5, 2012 14:41

3D hemisphere

1 Attachment(s)
Hi, I have some problem related to this topic: I want to compute drag coefficient on a hemisphere and I know that the best way is an axisymmetric simulation. but for training I want to run a 3D simulation and need a 3D mesh.
actually I couldn't make a good one with ANSYS ICEM!
Thanks.:)

 Far June 5, 2012 15:09

Follow shpere-cube tutorial. What do you mean by good quality?

 Far June 5, 2012 15:41

1 Attachment(s)
were you looking for this. Just deleted lower part of sphere!!! do you need it? I am not sure.

 Far June 6, 2012 10:09

1 Attachment(s)
try this.......strategy is similar to sphere-cube tutorial

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