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Old   November 24, 2003, 13:39
Default boundary condition and hydrostatic pressure
Atit Koonsrisuk
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I conclude after reading some topics in this forum that when I model flow with buoyancy effect, I have to include the hydrostatic pressure with the boundary conditions. Is my understanding right? I model the flow in a equipment with high chimney. This equipment allow the working fluid to flow in through the inlet portion and flow out through a chimney. The flow arise due to natural convection within the equipment. Do I have to add the hydrostatic pressure to the 'inlet' and 'outlet' boundary conditions. Actually I already tried to add it, but I got the divergent solution. Thank you very much.

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Old   November 24, 2003, 13:49
Default Re: boundary condition and hydrostatic pressure
Atit Koonsrisuk
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Since the density will be changed with temperature, then I enter the expression for density as the function of temperature in the fluid property form when I define the model. Then I followed the suggestion in one topic that specify 'density*g*y' as the expression for pressure in the boundary condition form. I got the error message say that 'density' is not available for this expression. Could anyone please suggest me how to fix this problem? Thank you very much.
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Old   November 25, 2003, 21:39
Default Re: boundary condition and hydrostatic pressure
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I suggest you read the handbook of CFX, you can get the method that solve your problem in tutorial 3.
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Old   December 7, 2003, 06:46
Default Re: boundary condition and hydrostatic pressure
Amit Katiyar
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hello Atit,

i also have the same problem as you have in your chimney problem. I suspect that the static pressure taken by cfx-5 is <p-rho*g*h>. so we should define this value only as proper boundary condition. but i didn't get proper results. I am also unanswered about this question.

share your views with me. amit

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