Boundary condition - FFT

cfdapprentice · June 22, 2010, 02:55

Boundary condition - FFT

I am working on simulating a two-phase flow 3-D fluidized bed. It is a granular flow interacting with gas.

When I created my mesh, the bottom part was declared as a “velocity-inlet”. Mainly walls on the sides and the top part is the outlet.

My question is:

I am not sure if I should declare it as “outflow” or “pressure-outlet”.

Can somebody tell what is more appropriate and explain me the difference between them?

The reason why I am asking the above question is because I am also trying to get the
FFT (Power Spectral Estimate) x frequency graph of the vertical forces.

Thank you!

cfdapprentice · June 23, 2010, 00:14

After asking some people, I got the answer to my question.
It might help others so I decided to post.

Since it is a two-phase flow, it is more apropriate to use "outflow".
"Pressure-outlet" is used mostly for gas.

sri99iitm · July 9, 2010, 05:42

hi ..did u completed 3d fludized bed simulation ..can u send case n data file to me plzzz.
if u dont have help me out plz..i have some doubts pertaining to udf and under relaxation factors ...
thx for telling it outflow . Its been very helpful for me
thx for replying in advance

June 22, 2010, 02:55	Boundary condition - FFT	#1
cfdapprentice New Member Join Date: Jun 2010 Location: London Posts: 3 Rep Power: 15	Boundary condition - FFT I am working on simulating a two-phase flow 3-D fluidized bed. It is a granular flow interacting with gas. When I created my mesh, the bottom part was declared as a “velocity-inlet”. Mainly walls on the sides and the top part is the outlet. My question is: I am not sure if I should declare it as “outflow” or “pressure-outlet”. Can somebody tell what is more appropriate and explain me the difference between them? The reason why I am asking the above question is because I am also trying to get the FFT (Power Spectral Estimate) x frequency graph of the vertical forces. Thank you!

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June 23, 2010, 00:14		#2
cfdapprentice New Member Join Date: Jun 2010 Location: London Posts: 3 Rep Power: 15	After asking some people, I got the answer to my question. It might help others so I decided to post. Since it is a two-phase flow, it is more apropriate to use "outflow". "Pressure-outlet" is used mostly for gas.

July 9, 2010, 05:42		#3
sri99iitm New Member srinivas Join Date: Feb 2010 Posts: 9 Rep Power: 16	hi ..did u completed 3d fludized bed simulation ..can u send case n data file to me plzzz. if u dont have help me out plz..i have some doubts pertaining to udf and under relaxation factors ... thx for telling it outflow . Its been very helpful for me thx for replying in advance