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vkrastev December 22, 2010 10:44

Buoancy driven suction
Hi all, I was just doing some trials on a (very) simplified thermal chimney model, consisting of a square duct with a lateral inlet on bottom (with lateral I mean a square opening orthogonal to the lower face of the duct) and an outlet on top. What I want to obtain is to impose the heating of a higher portion of the air volume inside the duct, so that It would begin to move towards the outlet and to generate a suction effect at the inlet. Well, as a solver I use buoyantPisoFoam, but till now the results are not so encouraging...The main problem is (I guess) that I'm not able to set proper boundary condition, especially at the inlet/outlet sections and in the heated region. So, my questions are:

1) Which should be a proper choice for p and U bc's at inlet and outlet? I've tried fixedValue and pressureInletVelocity for p and U at the inlet and totalPressure/zeroGradient for p/U at the outlet, but the flow tends to enter upstairs and exit downstairs instead of doing exactly the opposite...

2) What about the heated region? Is it better to set a fixedValue for the temperature at the heated walls or a fixed heat flux? In the latter case, does it exist a fixedHeatFlux (or something similar) bc in OF 1.6?

Any comments and/or suggestions would be really appreciated

Thank you in advance


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