# How model natural convection in water?

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 January 27, 2010, 10:45 How model natural convection in water? #1 New Member   Daniele Join Date: Jan 2010 Posts: 8 Rep Power: 8 Hi! I'm modeling a problem of natural convection induced by a thermal source. Fluid is water. I've already set 'Density' as 'boussinesq', 'Thermal Expansion Coefficient' is 1/T, (where T is T of film). It seems that everything si right, but the output is not satisfactionary. Why?

 January 27, 2010, 10:59 #2 New Member   Daniele Join Date: Jan 2010 Posts: 8 Rep Power: 8 *satisfactorily, excuse the mistake! BC are all costant temperatures, there's a heat source in the centre, and the flow il laminar. Thank you sincerely for the help you will be able to give me.

 January 27, 2010, 12:18 #3 New Member   Daniele Join Date: Jan 2010 Posts: 8 Rep Power: 8 I need your advice. Is there somebody who could answer to me?

January 27, 2010, 13:58
boussinessq hyp
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CFDtoy
Join Date: Mar 2009
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Hi,
try using different function for rho(T) for water....1/T settings may just not be right for water. when pv = rho*R*T, you can easily derive expansion coefficient = 1/T but thats for gases..for water, the expansion is much lower.

try searching for water thermal expansion coefficient and validate the code with some known results first and then experiment for different beta.

/CFDtoy

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 January 28, 2010, 04:23 #5 New Member   Daniele Join Date: Jan 2010 Posts: 8 Rep Power: 8 Hi! Thank you very much for your suggestion. I think that I'll set the density as 'piecewise polynomial'.. Have a nice CFDay!!

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