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June 20, 2018, 14:30 |
Force coefficient Cf
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#1 |
New Member
Prasenjit Sanyal
Join Date: May 2016
Posts: 25
Rep Power: 9 |
Previously I calculated cfx and cfy as Cfx=Fx/(0.5*rho*vz^2)*A Cfy=Fy/(0.5*rho*vz^2)*A where A is projected area in the direction of wind But in some paper they are taking Ax= Projected area normal to the direction of wind for cfx and Ay=Projected area parrallel to the direction of wind which one is correct ? |
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June 21, 2018, 07:17 |
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#2 |
New Member
HBR
Join Date: Jun 2018
Posts: 6
Rep Power: 7 |
You can calculate them following the convention you want to adopt. I mean, what is in the denominator (\rho v^2 A) is a simple number, dimensionally consistent with Fx to make their ratio dimensionless.
Usually A is chosen such as it is the area that the flow "views". But you can decompose the speed vector into its components (v_x,v_y) and calculate the areas A_x A_y respectively as well. |
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June 23, 2018, 09:47 |
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#3 |
Member
Sangeet
Join Date: Jun 2017
Location: India
Posts: 43
Rep Power: 8 |
Hello,
There's no convention as to how the reference area is chosen. Contrary to the above post, the reference area isn't chosen based on what the flow sees. It depends on what kind of work you are doing and the convention followed in that area. For example, in my work with airfoils, the literature that I consult with to check the results, use the chord length * span as the reference area. Though you are free to use what you want to non-dimensionalize your data. I would suggest that you look at the literature related to your work and follow the convention that it follows. This will make is easier for you comapre your results with the published data. Last edited by sangeet; June 25, 2018 at 09:30. |
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