[zackufairu]

Hi people
I am learning ICEM and attempted to do ahmed body meshing tutorial.
What i got was an absolute disaster on top of the car in terms of mesh.
Could you tell me why am i getting this and what i can do to remedy it?
Thank you

[shereez234]

Hello;

Can you post more pics of your blocking and perhaps the surface mesh as well.

If you want proper help can you upload the blocking file? or if you can't thats okay

[bluebase]

Hi Zack,

i agree with shereez, more pictures might be needed.
From the first picture alone, i suggest you to check all surfaces and faces, as well as its associations in this area. You might redo the associations as intended.

With regards,
Sebastian

[zackufairu]

13.PNG

11.jpg

14.PNG

12.jpg


hope this makes it clear
I really am perplexed did the tutorial 2 times now

[diamondx]

Association problem, 100%. make sure curves are associated with their respective lines. What you can do is cancel all associations. and re-do it. you don't have to generate a new blocking

[shereez234]

Ali is right. Redo the associations. Associate every line to curve and perhaps if that's not good enough associate the face as well. But the geometry of ahmed body is very simple so that just associating every edge to it's curve will be good enough to represent the geometry.

Regards
Shereez

[zackufairu]

thank you for your replies
I HAVE found the problem I think and it may not be association.
You see the ahmed car body internally is an empty shell thus the inside of the car was giving a distorted mesh,this was due to no block at its left side(where symmetry condition will be applied)
If the internal body was removed and then premesh regenrated the mesh was much cleaner(normal looking)
Am i correct to remove the mesh from within the body?and with this logic i should ignore the health of the mesh inside the body?
Do let me know
Thank you

[bluebase]

Hi zack,

probably, the inside of the ahmed body is of no interest to you. Hence, it's correct to remove these blocks.

It can be a good idea though to not delete those blocks "permanently" in ICEM. That way you can keep the edge relations between neighboring blocks.

[zackufairu]

Status:I am trying to improve the mesh quality now.
Thank you people for your support.
This is kind of wierd that even ansys tutorials dont explain much about improving mesh quality
Right now I am aiming for determinant 3x3x3 quality >0.5 as my benchmark.
please suggest what I can do to improve mesh quality other than increasing the nodes and why the mesh is bad at certain points.(that curved line at rear bottom is particulary persistent)

ahmed clean.jpg

ahmed rear side.jpg

ahmedrearbottom.PNG

ahmed11.PNG

[shereez234]

Originally Posted by zackufairu

Right now I am aiming for determinant 3x3x3 quality >0.5 as my benchmark.
please suggest what I can do to improve mesh quality other than increasing the nodes and why the mesh is bad at certain points.(that curved line at rear bottom is particulary persistent)

Hello zackufairu

Great that you are able to resolve the previous issue. Quality is really a matter of the solver. If you are taking this model to ANSYS Fluent then Orthogonal quality and skew is the most important with a reasonable aspect ratio I believe.

I have always found that having a quality of 0.1 and above gives accurate results. However the solution is also dependent on number of mesh elements ( mesh independent solution) and solver settings ( Right turbulence models, viscosity value, and relaxation factors). If you will reach there and find some problems do not hesitate to come back and ask.