Rayleigh-Benard problem with buoyanBoussinesqSimpleFoam

Logan Page · April 30, 2011, 17:28

Hi Foamers

I was wondering if anyone has tried solving the classical Rayleigh-Benard problem with buoyanBoussinesqSimpleFoam?

I have been trying to solve it for the following case:

Laminar, steady-state and 2D flow
free-free boundary condition
Pr = 0.72
Ra = 3000
H= 1
L = 10
Thot = 1
Tcold = Tref = 0
g = -1
beta = 1
nu = 0.01549193

nu is obtained from the Ra number relationship
nu = 1/(alpha*Ra) = Pr/(nu*Ra)
thus nu = sqrt(Pr/Ra)

From what ive found Ra_crit should be around 657.51, i.e. any Ra number smaller than that will have no convection. Thus for Ra = 3000 i should indeed have convection for this case.

However I am not getting any convection when OpenFOAM solves this case. I get a pure conduction solution with 10 W heat flux at the top and bottom faces. If solved in Fluent i get the correct solution.

Any advise would be appreciated

vnarayana · March 11, 2016, 11:17

Did you get the result for convection. i am also doing and struggling to get the results ?

thomasArk47 · March 13, 2016, 14:47

Hello,

hae a look at the Mukul P. post named "unsteady solver in OpenFoam" (the name is not explicit indeed). Sorry I don't konw to put the link

but it is one of the last on the forum.

He looks at the same things than you I guess.

You should work together maybe.

April 30, 2011, 17:28	Rayleigh-Benard problem with buoyanBoussinesqSimpleFoam	#1
Logan Page Member Logan Page Join Date: Sep 2010 Posts: 38 Rep Power: 16	Hi Foamers I was wondering if anyone has tried solving the classical Rayleigh-Benard problem with buoyanBoussinesqSimpleFoam? I have been trying to solve it for the following case: Laminar, steady-state and 2D flow free-free boundary condition Pr = 0.72 Ra = 3000 H= 1 L = 10 Thot = 1 Tcold = Tref = 0 g = -1 beta = 1 nu = 0.01549193 nu is obtained from the Ra number relationship nu = 1/(alphaRa) = Pr/(nuRa) thus nu = sqrt(Pr/Ra) From what ive found Ra_crit should be around 657.51, i.e. any Ra number smaller than that will have no convection. Thus for Ra = 3000 i should indeed have convection for this case. However I am not getting any convection when OpenFOAM solves this case. I get a pure conduction solution with 10 W heat flux at the top and bottom faces. If solved in Fluent i get the correct solution. Any advise would be appreciated

March 11, 2016, 11:17	Rayleigh benard convection	#2
vnarayana New Member narayana vekamulla Join Date: Oct 2015 Posts: 15 Rep Power: 11	Did you get the result for convection. i am also doing and struggling to get the results ?

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March 13, 2016, 14:47		#3
thomasArk47 Member Thomas Boucheres Join Date: May 2013 Posts: 41 Rep Power: 13	Hello, hae a look at the Mukul P. post named "unsteady solver in OpenFoam" (the name is not explicit indeed). Sorry I don't konw to put the link but it is one of the last on the forum. He looks at the same things than you I guess. You should work together maybe.