
[Sponsors] 
May 17, 2013, 05:03 
How to calculate the vehicle front/rear lift forces

#1 
New Member
Fayong.zhang
Join Date: Nov 2012
Posts: 2
Rep Power: 0 
How to calculate the vehicle front/rear lift force? I know how to calculate the whole car lift force, but how to calculate the front/rear lift force separately?


May 17, 2013, 06:30 

#2 
Senior Member
Lefteris
Join Date: Oct 2011
Location: UK
Posts: 199
Rep Power: 7 
Which software are you using?
__________________
Lefteris 

May 17, 2013, 10:15 

#3 
New Member
Fayong.zhang
Join Date: Nov 2012
Posts: 2
Rep Power: 0 

May 19, 2013, 08:19 

#4 
Senior Member
Gajendra Gulgulia
Join Date: Apr 2013
Location: Munich
Posts: 138
Rep Power: 6 
Hey Zhang
I am not giving you a software custom method to calculate the vehicle lift. What I am about to mention in the foregoing discussion is a standard method for calculating the lift/drag forces at any region of the body The region of interest has to be explicitly defined in the code. For lift coefficient calculation you need to have the area (Vector) of the region normal to the longitudinal direction of the vehicle, say A, and the density of the fluid flowing over the surface of the vehicle, say d, The force has to be calculated by the expression in the code you will be using (all of the softwares nowadays have an inbuilt expression to calculate the force on the surface of interest. This force, say F, is fund out by running the simulation. Then you can create a custom expression to get the force coefficient and running the same in iteration. The following formula has to be used for calculating the force coefficient: C= F/(0.5*d*A) For drag coefficient F is along the direction opposite to the fluid flow or along the direction of the area vector, and for lift coefficient F is along the direction aligned with the vertical of the local coordinate system 

May 19, 2013, 08:21 

#5 
Senior Member
Gajendra Gulgulia
Join Date: Apr 2013
Location: Munich
Posts: 138
Rep Power: 6 
.. and yeah if you are using STAR CCM+ , you can get the example in one of the tutorials given in the help file of the package
PS sorry for the long reply posted previously.. it's just that I emphasize a lot in keeping the basics clear 

May 19, 2013, 13:23 

#6 
Senior Member
Join Date: Mar 2009
Location: Austin, TX
Posts: 138
Rep Power: 11 
You can get the aerodynamic lift, drag and moment from your CFD software and then do some very simple static analysis to determine the aerodynamic load on each axle.


May 19, 2013, 13:50 

#7 
Senior Member
Lefteris
Join Date: Oct 2011
Location: UK
Posts: 199
Rep Power: 7 
I think that in Fluent you can choose the surface that you want and have it calculate the aerodynamic forces on these surfaces. I'm not so sure about that though.
Lift is in the direction perpendicular to the flow direction.
__________________
Lefteris 

Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Lattice Boltzmann, LIFT and DRAG forces  Puigar  Main CFD Forum  0  October 15, 2012 08:57 
using forces for geting drag and lift force magnitude?  510_  Main CFD Forum  2  October 28, 2010 11:42 
how to calculate forces on the wall with free surface?  phsieh2005  Main CFD Forum  2  July 13, 2010 08:11 
Trying to calculate lift and drag forces  vkrastev  OpenFOAM  0  January 27, 2010 12:33 
Calculate forces without hydrostatic pressure  geir_oye  FLUENT  4  November 12, 2009 10:12 