[aftertime]

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]

attach geometry file

[aftertime]

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

[Far]

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

[aftertime]

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]

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

[aftertime]

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 ...
http://encodable.com/uploaddemo/files/sphere.zip
( 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]

Ok . Done in five minutes (I wasn't counting .)

[Far]

Your case is much difficult than your teacher did.

[diamondx]

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]

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

[Far]

i must add that wind hit the flat side of hemisphere in tunnel

From left to right? Any angle of attack?

[aftertime]

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

[Far]

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

[aftertime]

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 .
http://uploading.com/files/c218e433/New%2Bfolder.zip/
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 .
again thanks for your help

* 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]

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]

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!
could you please help me?
Thanks.

[Far]

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

[Far]

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

[Far]

try this.......strategy is similar to sphere-cube tutorial