natural convection of a 2D plate with bousinesqSimpleFoam

emjay · December 31, 2017, 12:13

Hello everybody,

i have some questions about my case.

As you can see in Drawing.png this simulation is a 2d case.
On the left side is a plate with a uniform temperature T_hot
Every other patch have symmetric boundary condition, except Top and bottom.

I tested some variations of boundary conditions for top- and bottom patch but i couldn't find the right combinations for one specific physical boundary condition.

top and bottom patch should behave like an farfield.
but i don't know which bc should i use for velocity, pressure...

velocity should be calculated
pressure should be on bottom-patch fixed value

The solver is a bouyant SimpleFoam with Boussinesq approximation.

May somebody can give me a hint.

Best regards
emjay

piu58 · December 31, 2017, 12:51

You have to specify in the thermophysicalProperties the dependency of the density of the fluid in dependence of the temperature. It is possible to give a polynom up to 7th grade (plus a constant value).

emjay · January 1, 2018, 10:36

Hello Uwe,

thank you for your interest on my problem, but i don't know how your answer match my question.

The question is which boundary conditions for the top and bottom patch are suitable to simulate an "open" boundary condition.

thank you in advance
emjay

piu58 · January 1, 2018, 10:55

That depensds what you intended for that wall.You may
- set it to the temperature of the fluid volume
- set it to zero gradient
I don't believe that it makes a huge difference.

December 31, 2017, 12:51		#2
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	You have to specify in the thermophysicalProperties the dependency of the density of the fluid in dependence of the temperature. It is possible to give a polynom up to 7th grade (plus a constant value). __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

January 1, 2018, 10:55		#4
piu58 Senior Member Uwe Pilz Join Date: Feb 2017 Location: Leipzig, Germany Posts: 744 Rep Power: 15	That depensds what you intended for that wall.You may - set it to the temperature of the fluid volume - set it to zero gradient I don't believe that it makes a huge difference. __________________ Uwe Pilz -- Die der Hauptbewegung überlagerte Schwankungsbewegung ist in ihren Einzelheiten so hoffnungslos kompliziert, daß ihre theoretische Berechnung aussichtslos erscheint. (Hermann Schlichting, 1950)

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January 1, 2018, 10:36		#3
emjay New Member Marko Josic Join Date: Dec 2010 Posts: 20 Rep Power: 15	Hello Uwe, thank you for your interest on my problem, but i don't know how your answer match my question. The question is which boundary conditions for the top and bottom patch are suitable to simulate an "open" boundary condition. thank you in advance emjay