Wall cell length calculator

This calculator allow you, depending on the desired y+ value, to estimate the size of the first wall cell.
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Methodology:

R_e =\frac{\rho U L_c}{\mu}
C_f = f(R_e)
\tau_w = \frac{C_f\rho U^2 }{2}
u_{\tau} =\sqrt{\frac{\tau_w}{\rho}}
\Delta y =\frac{y^+ \mu}{u_{\tau} \rho}

Correlations of wall friction coefficients C_f = f(R_e) :

Schlichting:

C_f = \frac{1}{(2log(R_e)-0.65)^{-2.3}}

ITTC 1957:

C_f = \frac{0.075}{(log(R_e)-2)^{-2}}

Prandtl’s one-seventh-power law:

C_f = \frac{0.027}{(R_e)^{-1/7}}

Blasius solution:

C_f = \frac{0.664}{(R_e)^{-1/2}}