How can I achieve my desired chord Reynolds number?

Moreza7 · July 24, 2020, 05:59

Hello,

I'm trying to simulate flow around an airfoil which its experimental results are achieved at the chord Reynolds number of 2.1E6 with the chord length of 0.6m and the Mach number of 0.15 and the kinematic viscosity of air at 15°C.

Now, my coordinates file of the airfoil gives the chord length of 1m. As the Mach number must be equal to the experiment, the freestream velocity is also equal to the experiment. But now if I use the kinematic viscosity of air at 15°C, the chord Reynolds number will be increased about 1Million.

Can I manually change the kinematic viscosity of the fluid to set the chord Reynolds number equal to the experiment?

Geetjev · July 26, 2020, 08:36

Hello,

As by my understanding, you should be able to lower the kinematic viscosity to obtain a lower Reynolds number and therefore have similar flow conditions.

However, if you have the same airfoil as the experiment in the coordinates file you could look into scaling your file to have a chord length of 0.6m. That way you can be certain you have the exact same conditions.

Hope this helps!

July 24, 2020, 05:59	How can I achieve my desired chord Reynolds number?	#1
Moreza7 Senior Member Join Date: Jan 2018 Posts: 121 Rep Power: 8	Hello, I'm trying to simulate flow around an airfoil which its experimental results are achieved at the chord Reynolds number of 2.1E6 with the chord length of 0.6m and the Mach number of 0.15 and the kinematic viscosity of air at 15°C. Now, my coordinates file of the airfoil gives the chord length of 1m. As the Mach number must be equal to the experiment, the freestream velocity is also equal to the experiment. But now if I use the kinematic viscosity of air at 15°C, the chord Reynolds number will be increased about 1Million. Can I manually change the kinematic viscosity of the fluid to set the chord Reynolds number equal to the experiment?

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July 26, 2020, 08:36		#2
Geetjev New Member Thijs-Gerrit Join Date: Jul 2020 Posts: 1 Rep Power: 0	Hello, As by my understanding, you should be able to lower the kinematic viscosity to obtain a lower Reynolds number and therefore have similar flow conditions. However, if you have the same airfoil as the experiment in the coordinates file you could look into scaling your file to have a chord length of 0.6m. That way you can be certain you have the exact same conditions. Hope this helps!