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-   -   Aerodynamics of an Automobile. (Floworks 2007) (http://www.cfd-online.com/Forums/floefd-floworks-flotherm/27166-aerodynamics-automobile-floworks-2007-a.html)

 Nicole Price May 13, 2008 16:11

Aerodynamics of an Automobile. (Floworks 2007)

Hi all,

I've been building and testing 1:1 models in solidworks of an SCCA D-sport Racer for several weeks/months. I've been pretty successful in getting usable relative results (reduced drag and/or increased total downforce), but I am having trouble in one area;

How do I go about setting up my analysis to allow me to determine loads at each tire? I want to be able to see how these increased downforce numbers are effecting my front to rear balance.

The solidworks documention has left things pretty vague to me. Could it be as simple as setting up a 4 seperate goals? (I looked into it, but couldn't find anything I could use as a 'pad' for each wheel).

 Dani May 14, 2008 08:57

Re: Aerodynamics of an Automobile. (Floworks 2007)

Yes, simply apply a surface goal on the surfaces of each tire and select the parameters of the goals. It is that simple. The goal then shows for example the forces or moments acting on these surfaces. What you cannot do is determine how much downforce the front wing is causing on the left or the right tire because the goal only gives you the forces of the fluid acting on the selected surfaces. If you want to know the force of the front wing on each tire, you will have to go by hand calculation of the simple mechanics or use COSMOSworks. Because in EFD or Floworks there is no mechanical translation of forces acting on one point to the other point.

 Nicole Price May 15, 2008 20:48

Well that blows... So I was sold a bag of garbage?

How would Cosmosworks be able to help me determine the total loads transfered to the contact patch of each tire due to aerodynamic drags and forces?

This is terribly rediculous if this is true. My solidworks reseller is of no use. All he says is that 'anything is possible with solidworks!'

Your answer also does not make total sense, as I can get cosmos to give me total down force and total drag of my models.

 Bill McEachern May 16, 2008 14:45

Re: Well that blows... So I was sold a bag of garb

Just 'cause some guy named Dani makes a post doesn't mean you need to go get all non-linear on us now.....

It has been awhile since I did this but I am pretty sure you can sum all or any the forces & torques acting on a particular surface relative to a co-ordinate system. You can then figure it out pretty simply with all the moments referenced to a single location. No big deal. You need to sum the "torques" on a surface about a known location (coordinate system) and if you know the lift then getting the center of lift is not that tough given you know the moment and the lift. Obviously, with the locations of the centers of lift you can figure out the load per tire with some sigma F=0. Hope that helps.

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