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-   -   I need to fix total volume fraction (https://www.cfd-online.com/Forums/fluent/43373-i-need-fix-total-volume-fraction.html)

Yasser January 17, 2007 07:32

I need to fix total volume fraction
 
hello i am using eulerian two phase model to simulate the flow in mixing tank. after post processing, i find the solid volume fraction become lower than its patched value ....

I read that another one used UDF to fix the total volume fraction to a certain value and he gave this link in the references

http//www.fluentusers.com/udf_archieve/udf_examples/UDF52.htm

but i don't have access to this site can anyone help me? thank you

Suijth January 17, 2007 12:12

Re: I need to fix total volume fraction
 
what is your simulation?

If you just want to keep the initial values of the vol fraction, you can turn off the volume fraction equation from solving it, in the solution controls panel..

-Sujith S Nair

Yasser January 17, 2007 12:24

Re: I need to fix total volume fraction
 
i am modelling two phase flow (solid-liquid) in mixing tank and thx for your suggestion

i don't want to keep the initial values ... i am studying solids concentration. just i need the total volume fraction in the tank be the same as initially patched.

thx for reply

Sujith January 17, 2007 16:19

Re: I need to fix total volume fraction
 
After patching your initial value of the patched variable will be over written. if u want to keep this for rest of simulation , you can switch off vof eqn.

Yasser January 17, 2007 16:47

Re: I need to fix total volume fraction
 
Thanks very much

Yasser January 18, 2007 01:25

Re: I need to fix total volume fraction
 
hello now i turned the equation off, but the volume fraction didn't change from cell to another

i need the volume fraction of solids to change from cell to another but i need the average volume concentration overall the tank to remain constant (which is not happened when turning the vof eq. on).

thx

Yasser


phire August 1, 2011 15:14

Urgent!!
 
pls yasser. I am working on the scour under pipeline. I am having the same problem you had. Where you able to find solution to it. I will really appreciate your response cos I have to submit my Thesis by august 9. thank you very much

phire August 1, 2011 15:15

Quote:

Originally Posted by Yasser
;138273
hello now i turned the equation off, but the volume fraction didn't change from cell to another

i need the volume fraction of solids to change from cell to another but i need the average volume concentration overall the tank to remain constant (which is not happened when turning the vof eq. on).

thx

Yasser

pls yasser. I am working on the scour under pipeline. I am having the same problem you had about the volume fraction reducing. Were you able to find solution to it. I will really appreciate your response cos I have to submit my Thesis by august 9 I can get result due to the wrong volume fraction result. thank you very much

zino August 3, 2011 08:10

I think you need mass conservation. there are options in multiphase. I have used eulerian approach. that approach provide mass conservation option

phire August 3, 2011 13:37

@zino Pls how do I set mass conservation because I am using eulerian granular phase model in which sand is taken as the granular phase while water is the continuum


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