Drag decreasing with decrease in temperature- Keeping Re and Mach same. why???
 

Dear all,
I am working on the validation of my cfd (using openFOAM) results on NACA0012. Experimental results are available at 0.3 Mach with 3.5 million Reynolds number.

I am matching finding the properties of air by matching the Mach and Reynolds number by using expressions of Re, Ma, equation of state, and Sutherland's equation.
For a particular temperature, I can find remaining properties of air such that Re, and Mach remains same.

Now, if I decrease temperature, the values of Cd are decreasing. I am unable to understand that why is it so.

CFD runs details:
Mesh count: 83k (structured)
Turb-Model: kw-SST
Y+ : < 0.1
Convergence criteria: 10e-7

Kindly guide me in this regard,
Thanks,

Regards,