# sutherland law?

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 August 24, 2013, 10:30 sutherland law? #1 New Member   TPRPR1 Join Date: Apr 2013 Posts: 13 Rep Power: 5 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 Last edited by tprpr1; August 24, 2013 at 13:33.

 August 27, 2013, 05:37 #2 Senior Member     Ehsan Join Date: Oct 2012 Location: Iran Posts: 2,209 Rep Power: 19 Hi whats "mo"? didn't you get anything by searching? __________________ Injustice Anywhere is a Threat for Justice Everywhere.Martin Luther King. To Be or Not To Be,Thats the Question! The Only Stupid Question Is the One that Goes Unasked.

 August 27, 2013, 06:49 #3 New Member   TPRPR1 Join Date: Apr 2013 Posts: 13 Rep Power: 5 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

 August 27, 2013, 07:23 #4 Senior Member   Lefteris Join Date: Oct 2011 Location: UK Posts: 199 Rep Power: 7 sutherland law? Anderson too in the Fundamentals of Aerodynamics 5th Edition, gives S=110 __________________ Lefteris

 August 27, 2013, 08:42 #5 Senior Member   Join Date: Dec 2011 Location: Madrid, Spain Posts: 134 Rep Power: 7 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.

August 27, 2013, 09:19
#6
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Lefteris
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Quote:
 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
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Lefteris

 August 27, 2013, 13:14 #7 Senior Member   Join Date: Dec 2011 Location: Madrid, Spain Posts: 134 Rep Power: 7 Hi, can you please elaborate? Thanks, Michujo.

August 27, 2013, 13:20
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Lefteris
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Quote:
 Originally Posted by michujo Hi, can you please elaborate? Thanks, Michujo.
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 August 27, 2013, 15:26 #9 New Member   TPRPR1 Join Date: Apr 2013 Posts: 13 Rep Power: 5 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

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