[tprpr1]

hi
i have a question regarding the Sutherland law
for air
s=110
mo=1.715
t0=273.11
does the co-efficients vary with altitude of air?
for example for 10000m mo=1.458e^-5
how do i calculate S?
thanks in advance

[immortality]

Hi
whats "mo"?
didn't you get anything by searching?

[tprpr1]

s=sutherland temperature
m0=reference viscosity
to=reference temperature
i looked at several places on the net
to=remains the same for all
s and m0 changes for different materials
However mo will change for different altitude for air(data available)
but i do not know how to calculate s corresponding to the new mo

[Aeronautics El. K.]

http://www.cfd-online.com/Forums/mai...rland-law.html

Anderson too in the Fundamentals of Aerodynamics 5th Edition, gives S=110

[michujo]

Hi, I would say that for a certain fluid the coefficients are constant, viscosity only changes with temperature. The viscosity of air varies indirectly with altitude through temperature.

Cheers,
Michujo.

[Aeronautics El. K.]

Originally Posted by michujo

Hi, I would say that for a certain fluid the coefficients are constant, viscosity only changes with temperature. The viscosity of air varies indirectly with altitude through temperature.

Cheers,
Michujo.

If you take air to be an ideal gas

[michujo]

Hi, can you please elaborate?

Thanks,
Michujo.

[Aeronautics El. K.]

Originally Posted by michujo

Hi, can you please elaborate?

Thanks,
Michujo.

I hadn't read carefully your post and I didn't know how to delete my post

[tprpr1]

thank you all for replying

so in other words the 3 coefficients mo ,to,s remain the same for any altitude as long as im taking air as ideal gas in fluent

the actual viscosity m will vary as a function of temperature t.
that clears my doubt .thank you