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IndrajitW October 15, 2013 05:52

Length of interface in VOF
Hi all,
I am simulating a two phase flow using VOF model in fluent. I need to know the length of the liquid vapor interface in the cell. This length of the interface is used in one of my UDF's.Is there any macro or something in fluent whic hcould give me acces to the interface length???:confused:

bansa9643 October 22, 2013 13:51

Look up Interfacial Area Density.. it will involve writing a udf which allows an estimation of the interface's "length" in each cell.

garvitgoel June 5, 2014 10:59

interface length in the cell
Can somebody please post more information on how to estimate the length of interface in the cell?

bansa9643 June 6, 2014 03:36

Check Yuri Egorov's (Ansys Fluent) year 2004, work on "Validation of CFD codes with PTS - relevant test cases".
Some approximations for calculating interfacial length have been provided as a function of volume fraction and its gradient in each interfacial cell.
This approximation was found to be best suited for curved interfaces:

A = 6 * alpha_l * alpha_g * SQRT( grad(alpha_l) * grad(alpha_g) )
A = 6 * alpha_l * (1-alpha_l) * mag ( grad(alpha_l))

A being the Interfacial area density
alpha_l the liquid volume fraction
grad(alpha_l) the gradient of liquid volume fraction

A UDF could then be used to calculate the interfacial length for each cell.


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