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Natural convection cavities high rayleigh numbers

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Old   September 24, 2008, 02:54
Default Natural convection cavities high rayleigh numbers
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tommy
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I'm doing some calculation on natural convection in cavities at high rayleigh numbers (Ra=10^10-10^16) and Pr = 0.71. I have serious convergence difficulties using a standard k-eps turbulence model. Does' anyone have any suggestions for me ??

Thanks you in advance
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Old   September 25, 2008, 07:25
Default Re: Natural convection cavities high rayleigh numb
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Rogerio Fernandes Brito
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change the scheme to upwind and try to see if it will converge or not.
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Old   September 25, 2008, 19:34
Default Re: Natural convection cavities high rayleigh numb
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Glenn Horrocks
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Hi,

The documentation has a discussion about obtaining convergence and you might get some ideas here: http://www.cfd-online.com/Wiki/Ansys...gence_criteria

Note that it is common for flows at these Rayliegh numbers will converge steady state as they are almost always transient. Are you running in transient mode?

Glenn Horrocks
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Old   September 27, 2008, 15:43
Default Re: Natural convection cavities high rayleigh numb
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pratik mehta
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Hi, I have done very similar simulation using fluent 2 yrs back and I see that certainly one has to be very strategic to get convergence for natural convection simulations . I would suggest that you solve the case steady for few iterations but soon change to transient since as Glenn says and I agree most of such flow are transient in nature.

Best of lucky
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