Sunday, January 10, 2010

VOF Simulations : Waves, Bubbles, Spillways....

Use of Volume-of-Fluid methods in wide environment has helped researchers gather tonnes of test cases / simulation studies that one could now use to enhance the interface capturing or try comparing the influence of other parameters such as turbulence in estimating the over all flow field.

This is particularly useful feature which encourages VOFers to try things that they werent sure before..since their random tests cannot be validated quite effectively. Being more towards the multiphase front, tests with VOF has intrigued me for a while and still does...Whenever, I come across tests / cases on multiphase modeling, Eulerian, VOF with advanced turbulence modeling, I tend to mark them for more in-depth analysis.

I am posting some of the VOF studies that once again found in my research directory. Hope it helps in providing someone with case study or for further analysis.

Anyone, having  developed a VOF method or trying its capability, has always come across the typical DAM breaking problem...tiring one ..appears in the to-do list all the time. The ERCOFTAC community has a typical 3D dam  case for readers

http://wiki.manchester.ac.uk/spheric/images/SPHERIC_Test2_v1p1.pdf

Find droplet deformation studies using PROST VOF code here:
http://www.math.vt.edu/people/renardyy/Research/Publications/56114.pdf

Some sample cases / validation studies: Hydraulic jump free surface modeling

http://www.iahr.org/publications/assets/jhr39-5/P2045.pdf

FLOW3D work on droplet based Microfluidics problem using VOF methods is available here

http://www.flow3d.com/pdfs/tp/micro_tp/FloSci-Bib12-09.pdf

Interestingly, recently I came across a similar question in CFD-online
http://www.cfd-online.com/Forums/fluent/71563-behavior-two-phase-flow-pipe.html#post242061

Similar discussions on mixing of gas / liquid flows invoking the question: should we use VOF or other Eulerian strategies...
My view is : its a case-by-case situation. Based on what one would like to capture and the refinement of the grids that one would like to achieve, VOF or other Eulerian methods can be appropriately put to test.

A presentation of combined VOF/ Level Set methods (which are becoming sort of popular these days ...)

http://www.ahd.tudelft.nl/~bendiks/nwo/cs.pdf

These methods try combining the effective mass conservation of VOF type schemes with production of sharp interfaces using the distance function based LEVEL set methods. I really havent tried exploring this option (implementing this idea) yet.

And, how about simulating WaterFalls for a change...hello Niagara !
http://www2.et.lut.fi/ttd/twophaseflow/Seminars/Multiphase_seminar_Waterfall_21_11_2006.pdf

LES/VOF studies of liquid jet breakup:
http://www.stanford.edu/group/ctr/Summer/SP08/3_3_Herrmann.pdf
http://pdf.aiaa.org/preview/CDReadyMFDC06_1188/PV2006_3730.pdf

Also, take a look at the study of liquid-metal flows
http://www.fusion.ucla.edu/apex/ISFNT6/simFNT.pdf

A more numerical study on "total volume conservation during free surface flows" can be found here
http://journals.tubitak.gov.tr/engineering/issues/muh-07-31-5/muh-31-5-6-0704-8.pdf

Collection of bubbles simulated using VOF ! Wow, now thats resource-intensive study !!
http://www.ahd.tudelft.nl/academy/abstracts/abstract_iwata.pdf

Comparisons of various CFD models in simulating flow field near tailrace zones : A nice report presented by US army corps.

http://www.pnl.gov/main/publications/external/technical_reports/pnnl-13467.pdf

btw, the report compares VOF methods in STAR, FLOW3D and they explain what other softwares were considered for this project and details on choosing STAR and FLOW3D !!!

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