Lift Coefficient in fluent (reference value)

tonytonygood · November 19, 2018, 06:57

For the fluent solver, it uses the force to deduce the coefficient, but what should be the Area i should set in reference value?

I am doing a car model, I get the downforce but the lift coefficient seems to be incorrect since i don't know the area (should I use surface area or cross sectional area?). is there any way to compute the coefficient directly?

Thank you!

LuckyTran · November 19, 2018, 08:57

The reference area is defined in the definition of lift coefficient. Depending on who you are, what day of the week it is, and what time of day it is, the reference area chosen can be anything. If you don't know what the reference area ought to be, then there's no meaning to lift coefficient and you should probably shouldn't be looking at the lift coefficient in the first place. Why isn't the lift force sufficient? Is there a need to examine the lift coefficient?

However, the reference area is often the frontal cross-sectional area (which has nothing to do with lift but this makes the lift and drag coefficients consistent). A better area is the planform area (again a projected area but viewed from above). Both are used. Normally it is a cross-sectional area and not an actual surface area.

November 19, 2018, 06:57	Lift Coefficient in fluent (reference value)	#1
tonytonygood New Member Yuk Tong Cheng Join Date: Oct 2018 Location: Hong Kong Posts: 2 Rep Power: 0	For the fluent solver, it uses the force to deduce the coefficient, but what should be the Area i should set in reference value? I am doing a car model, I get the downforce but the lift coefficient seems to be incorrect since i don't know the area (should I use surface area or cross sectional area?). is there any way to compute the coefficient directly? Thank you!

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November 19, 2018, 08:57		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,751 Rep Power: 66	The reference area is defined in the definition of lift coefficient. Depending on who you are, what day of the week it is, and what time of day it is, the reference area chosen can be anything. If you don't know what the reference area ought to be, then there's no meaning to lift coefficient and you should probably shouldn't be looking at the lift coefficient in the first place. Why isn't the lift force sufficient? Is there a need to examine the lift coefficient? However, the reference area is often the frontal cross-sectional area (which has nothing to do with lift but this makes the lift and drag coefficients consistent). A better area is the planform area (again a projected area but viewed from above). Both are used. Normally it is a cross-sectional area and not an actual surface area.