How do I calculate the Reynolds number of a wing with wing chord,1.2m and speed of 60km/henter image description here


1 Answer 1


One way is to see what the following NASA links have to say about it and possibly using the calculator they have at the bottom of either page.


The similarity parameter for viscosity is the Reynolds number. The Reynolds number expresses the ratio of inertial forces to viscous forces. From a detailed analysis of the momentum conservation equation, the inertial forces are characterized by the product of the density $\rho$ times the velocity $V$ times the gradient of the velocity $dV/dx$. The viscous forces are characterized by the viscosity coefficient $\mu$ times the second gradient of the velocity $d^2V/dx^2$. The Reynolds number $Re$ then becomes:

$$Re = (\rho \cdot V \cdot dV/dx) / (\mu \cdot d^2V/dx^2)$$

$$Re = (\rho \cdot V \cdot L) / \mu$$

where $L$ is some characteristic length of the problem.


The dynamic viscosity coefficient divided by the density is called the kinematic viscosity and given the Greek symbol $\nu$

$$\nu = \mu / \rho$$

$$Re = V \cdot L / \nu$$

The units of $\nu$ are length^2/sec.


The Reynolds number expresses the ratio of inertial (resistant to change or motion) forces to viscous (heavy and gluey) forces.

  • 2
    $\begingroup$ I've edited the post for you, but please consider revising my edit and adding any extra information you think should be added. $\endgroup$
    – Federico
    Aug 2, 2018 at 8:02

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