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ConnClark · 09-13-2011, 04:17 PM

It can predict it provided you have modeled every thing right. What I'm saying is things like how smooth the surface is and gaps in body panels on the car are going to have some effect on the air flow that you have to quantify for the model.

Another thing that is very very important is getting a good mesh of calculation points. Too many points and your simulation will take too much memory and time to run. Too few and you won't get valid results. As I understand it there are formulas that can give you a starting point, but knowing this is something that comes with experience and looking at results.

There are ways to go about this to get a good approximation. One method is to model a test case that someone has gone through and tested thoroughly in a wind tunnel and start tweaking parameters in the simulation until you get very similar results. Then you can start testing your model. A common test case for car simulations is the Ahmed Bluff body.

start reading through this thread on this forum

Automotive test case -- CFD Online Discussion Forums

Then get a copy of openfoam running and look at the motorcycle test case and learn how to view the data with paraview.

Sadly my free time is not predictable so I don't have time to learn it to the degree required.

you can also chat with someone on the internet relay chat (irc) on

irc://freenode/openfoam-irc

be patient the people there are from all over the world and in different time zones

Edit: I was told this would be a good link for someone to look at http://www.icaen.uiowa.edu/~me_160/L...medcarrodi.pdf

09-13-2011, 04:17 PM	#8 (permalink)
ConnClark DieselMiser Join Date: Jun 2008 Location: Richland,WA Posts: 985 Das Schlepper Frog - '85 Mercedes Benz 300SD 90 day: 23.23 mpg (US) Gentoo320 - '04 Mercedes C320 4Matic 90 day: 22.44 mpg (US) Thanks: 46 Thanked 231 Times in 160 Posts	It can predict it provided you have modeled every thing right. What I'm saying is things like how smooth the surface is and gaps in body panels on the car are going to have some effect on the air flow that you have to quantify for the model. Another thing that is very very important is getting a good mesh of calculation points. Too many points and your simulation will take too much memory and time to run. Too few and you won't get valid results. As I understand it there are formulas that can give you a starting point, but knowing this is something that comes with experience and looking at results. There are ways to go about this to get a good approximation. One method is to model a test case that someone has gone through and tested thoroughly in a wind tunnel and start tweaking parameters in the simulation until you get very similar results. Then you can start testing your model. A common test case for car simulations is the Ahmed Bluff body. start reading through this thread on this forum Automotive test case -- CFD Online Discussion Forums Then get a copy of openfoam running and look at the motorcycle test case and learn how to view the data with paraview. Sadly my free time is not predictable so I don't have time to learn it to the degree required. you can also chat with someone on the internet relay chat (irc) on irc://freenode/openfoam-irc be patient the people there are from all over the world and in different time zones Edit: I was told this would be a good link for someone to look at http://www.icaen.uiowa.edu/~me_160/L...medcarrodi.pdf __________________ Last edited by ConnClark; 09-13-2011 at 05:07 PM..