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How to transform (mass flow rate) boundary condition from 3D to 2D?

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Old   October 18, 2012, 03:26
Question How to transform (mass flow rate) boundary condition from 3D to 2D?
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Hello everybody,

I'm using CFD-Fluent to simulate gasification. In my case, mass flow rate that enter gasifier column is 0,0074 kg/s of coal. I want to simulate with 2D geometry. Only half of the domain with is modeled because of symmetry. Is it same the number of mass flow rate in 3D and 2D? Is the mass flow rate used in 2D unchanged (0,0074 kg/s)? Or the mass flow rate must be devided to transform in 2D? I hope you can help me. Thanks.

Last edited by nurul efha; October 18, 2012 at 04:09.
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Old   October 20, 2012, 13:29
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Hi.
Are you using 2D Ax-symmetric? If yes, mass flow should be divided by (2*PI). You are just modeling 1 rad of the whole circle.
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Old   October 21, 2012, 17:59
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Quote:
Originally Posted by nurul efha View Post
Hello everybody,

I'm using CFD-Fluent to simulate gasification. In my case, mass flow rate that enter gasifier column is 0,0074 kg/s of coal. I want to simulate with 2D geometry. Only half of the domain with is modeled because of symmetry. Is it same the number of mass flow rate in 3D and 2D? Is the mass flow rate used in 2D unchanged (0,0074 kg/s)? Or the mass flow rate must be devided to transform in 2D? I hope you can help me. Thanks.
HI
You had better use intensive property for your simulation and further calculation.it is an easy way to get rid of changing units in 2.d or 3.d . i mean instead of using mass flow rate(which is an extensive property) just use velocity(intensive property)
good luck
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Old   October 21, 2012, 20:47
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Originally Posted by eng_s_sadeghi View Post
Hi.
Are you using 2D Ax-symmetric? If yes, mass flow should be divided by (2*PI). You are just modeling 1 rad of the whole circle.
I'm using 2D planar...
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Old   October 21, 2012, 20:49
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Originally Posted by misagh View Post
HI
You had better use intensive property for your simulation and further calculation.it is an easy way to get rid of changing units in 2.d or 3.d . i mean instead of using mass flow rate(which is an extensive property) just use velocity(intensive property)
good luck

I think so. Thanks...
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Old   October 27, 2012, 14:03
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Quote:
Originally Posted by eng_s_sadeghi View Post
Hi.
Are you using 2D Ax-symmetric? If yes, mass flow should be divided by (2*PI). You are just modeling 1 rad of the whole circle.

Can you expand on this ? I have always entered the full mass flow for axisymetric problems, not a 1 rad slice...

Quick search to find a Fluent manual online, reveals the following, (v6.3)

http://hpce.iitm.ac.in/website/Manua...ug/node227.htm

Quote:

Note that for axisymmetric problems, this mass flow rate is the flow rate through the entire ( -radian) domain, not through a 1-radian slice.
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