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 dreamliner2011 May 3, 2011 13:45

Need help on meshing a car profile

2 Attachment(s)
Hello CFD folks,
I am meshing an electric car at a velocity of 65 mph to capture the drag over the profile, and below are my topology and meshing in ICEM. I am not able to write out the mesh file for solver because It was said some mesh element can not be produced. Someone could give me some advise on:

1) The topology (6 blocks) looks good for this model? Any suggestion?

2) How to create an O-grid around the profile?
I applied O-grid by selecting block 13, profile's block, but this messed up the whole topology by creating so many other blocks around the profile.

I am looking forward help from the forum.

Thank you.

-Matt

http://www.cfd-online.com/Forums/att...1&d=1304444010

http://www.cfd-online.com/Forums/att...1&d=1304443289

 dreamliner2011 May 9, 2011 15:51

 PSYMN May 9, 2011 17:37

Steps...

There is a 2D car tutorial... Have you tried that?

This blocking looks OK, although it may have been built strangely (not how I would have done it).

If it were me, I would have started with a single block for the whole domain, then split once vertically to capture the back of the "car". Then again vertically to capture the bottom of the car. Then use Ogrid and select all the blocks and select all the edges along the bottom and exit. Apply and you will get your nice quarter ogrid. Associate and Fit the "Hgrid" portion of this quarter Ogrid to the body of your car. Put the Hgrid block that is within the car into a new Blocking Material called "CAR" (do this by right clicking on the parts branch of the tree to create a new part).

Then the boundary layer Ogrid becomes easy. Do you want it to just be around the car or around the car and the block below and or behind it?

Select the blocks you want to wrap around, then change the Ogrid option to "around blocks" (normally it goes inside out). If you want the Ogrid to go into the floor, don't forget to select that bottom edge also...

Apply, set sizes, check quality, adjust, etc.

If you get that same error message again, you will need to include it to get specific help.

Best regards,

Simon

 dreamliner2011 May 10, 2011 02:24

To Simon:
Thanks a lot for the detailed reply. But I am afraid I am not clear your topology yet. You mean:

1) The 1st single block is a rectangle,

2) then 2 split: 1 vertical line at the back of the car, another one at the front.

3) O-grid ...

Regarding to my topology, I used the topology for an airfoil to capture smooth flow over the spheroid-shaped car profile. I thought it could be better than a rectangular topology. The topology has 6 blocks, and the focus are on block 17 (friction drag near the wall), block 21 (separation behind the car), block 13 (flow under the car, ground, effect). But I was not able to create an O-grid around the profile. It will be great if you can comment on how to fix this topology for an O-grid.

Also, I focus on the O-grid around the car (not include the behind and the bottom)

Again, thanks a lot for your help.

Regards,
-Matt

 PSYMN May 11, 2011 18:47

Hands on help...

2 Attachment(s)
This is what I mean...

This is done with a top down blocking and only took a couple minutes...

You could stop here, without the ogrid around the car...
Attachment 7669

Or you could add an Ogrid. Here is one variation where I put the Ogrid around just the car...
Attachment 7670

But you could also put the ogrid around the car and the block below it (as is done in the 2D car tutorial). You could also do variations to get a nice ogrid in the wake region that would capture that recirculation very well...

Play with it and have fun, but definitely do the tutorials... The airfoil tutorial I put on youtube will also help.

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