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- - **Doubt about calculating the frictional velocity over an airfoil**
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Doubt about calculating the frictional velocity over an airfoilHi there,
Recently I read a post in a blog about estimating the initial cell height in a simulation of an aerofoil, this estimation includes the calculation of the frictional velocity over the aerofoil wall but the equation is not clearly written and I don't know if the right form is: Vt = Vinf*2*(Cf)^0.5 or: Vt = Vinf*(Cf*2)^0.5 Vinf : is the flow velocity Cf : is the skin friction coefficient Any help will be appreciated! |

Quote:
Vt = Vinf(Cf/2)^0.5 Starting with definition of Cf Cf(0.5*density*Vinf^2) = Tau Vt = sqrt(Tau/density) = sqrt ( 0.5*Cf*Vinf^2) = Vinf*sqrt(Cf/2) That particular work may have used a different definition of friction coefficient so that a factor of 4 may have been introduced. Which would yield the formula you already provided. |

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