Drag and Lift calculation

tjwldhks79 · September 10, 2024, 22:04

I understand that in the formulas for drag and lift, different areas are used.

I also understand that this area can be set in the reference values.

In that case, isn’t it impossible to calculate drag and lift at the same time?

Since the areas used for each are different, and there is only one area that can be input in the reference values, shouldn’t we calculate drag and lift separately, one after the other?

However, in the reference videos and materials, it seems that they are calculating both together...

Could you please give me some advice?

HHOS · September 27, 2024, 13:17

Drag and Lift coefficients are given using a reference area, the same one for both.

The area is the cross section of the body, perpendicular to the flow direction. Now, that area would vary depending on the direction of the flow, but then the coefficient would give you a little information if you are to compare two situations. Hence that value is fixed and the dimensionless number is the one adopting the change, so that you can compare stuff.

You can also obtain the forces in N instead and work with that if dimensionless numbers are confusing.

Maybe helps, maybe not

September 10, 2024, 22:04	Drag and Lift calculation	#1
tjwldhks79 New Member eddy Join Date: Jan 2024 Posts: 24 Rep Power: 2	I understand that in the formulas for drag and lift, different areas are used. I also understand that this area can be set in the reference values. In that case, isn’t it impossible to calculate drag and lift at the same time? Since the areas used for each are different, and there is only one area that can be input in the reference values, shouldn’t we calculate drag and lift separately, one after the other? However, in the reference videos and materials, it seems that they are calculating both together... Could you please give me some advice?

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September 27, 2024, 13:17		#2
HHOS Member Join Date: Jul 2013 Posts: 98 Rep Power: 13	Drag and Lift coefficients are given using a reference area, the same one for both. The area is the cross section of the body, perpendicular to the flow direction. Now, that area would vary depending on the direction of the flow, but then the coefficient would give you a little information if you are to compare two situations. Hence that value is fixed and the dimensionless number is the one adopting the change, so that you can compare stuff. You can also obtain the forces in N instead and work with that if dimensionless numbers are confusing. Maybe helps, maybe not