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mystic_cfd December 10, 2002 03:51

free surface inside a stirred tank
I am modelling flow in a stirred tank with a free top surface. Presently I solve the case using geo-reconstruct, but this consumes huge amounts of time - my feeling is that its the free surface algorithm. 2 questions:

1) which of the other VOF can be recommended for the free surface if the actual shape and location is not mission critical.

2) is there a way to monitor how much time the solver spends on solving the geo-reconstruction VOF?


MissNancy December 10, 2002 04:10

Re: free surface inside a stirred tank
1) geo-reconstruction VOF 2) what do you mean by that, do you mean how much extra time it takes to calculate the VOF part as compared to not considering the free surface? Why do you need this ??


mystic_cfd December 10, 2002 05:50

Re: free surface inside a stirred tank
1) when using Fluent 6, the recommended (by manual) option for solving VOF problems, is the geo-reconstruct method, described as a piecewise linear reconstruction of the VOF interface.

2) some time in the iteration loop will be spent doing this interface reconstruction - in my case I have a feeling it takes "forever". i would like to know if anyone has ideas on how to measure this.

MissNancy December 10, 2002 06:22

Re: free surface inside a stirred tank
At the end of the day, you will conclude that "The VOF simulation in Fluent is total sh**t*"

Sorry for my language :)


boris December 11, 2002 04:07

Re: free surface inside a stirred tank
If the free-surface is not so critical in your problem, you maybe can try implicit Eulerian with second order discritization scheme. It is much faster. But, the interface between two phases obtained from the results is not sharp. That is the limitation. VOF of Fluent is really frustrating. I totally agreed with Miss Nancy. So, be patient.

stan tonks December 11, 2002 10:27

Re: free surface inside a stirred tank
If the surface is not mission-critcal why not model it as a no-slip boundary

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