# Rayleigh number Custom field function

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 October 13, 2017, 00:26 Rayleigh number Custom field function #1 New Member   Praphul T Join Date: Dec 2013 Location: Bangalore, India Posts: 23 Rep Power: 8 Hi , I would like to plot a custom field function of Rayleigh number with time in Fluent. ( I am simulating a natural convection problem in a 3D rectangular enclosure ). The formula for Rayleigh number is . I would like to get the values of these fluid properties from the simulation. The problem is i am unable to find these properties and constants inside custom field function in fluent while defining the cff. Is there a solution to this problem ? Can anyone guide me on how to implement it ? Thanks in advance.

 November 4, 2017, 09:26 #2 New Member   Praphul T Join Date: Dec 2013 Location: Bangalore, India Posts: 23 Rep Power: 8 It will be certainly helpful if some can help me on this issue. It might seem trivial to some of you but can help a lot in getting ahead in the learning curve.

November 13, 2017, 01:48
#3
Member

Vignesh Lakshmanan
Join Date: Nov 2016
Location: India
Posts: 65
Rep Power: 5
Quote:
 Originally Posted by praphul Hi , I would like to plot a custom field function of Rayleigh number with time in Fluent. ( I am simulating a natural convection problem in a 3D rectangular enclosure ). The formula for Rayleigh number is . I would like to get the values of these fluid properties from the simulation. The problem is i am unable to find these properties and constants inside custom field function in fluent while defining the cff. Is there a solution to this problem ? Can anyone guide me on how to implement it ? Thanks in advance.
You know g is 9.81; Your beta is thermal expansion coefficient, which is 1/T (1/fluid temperature). L is characteristic length which is Volume of the body/Surface area of the body; Dynamic viscosity (Nu) , Diffusivity (alpha) can be easily found onlne at the corresponding fluid temperature

 Tags custom field function., fluent, natural convection, rayleigh number, udf