Hi...

Can anyone tell me that what is the convient way to model a free surfece flow...?

Thanks in advance..!

---sushii..

The VOF model is the best model used for free surface flow.

Hi kb,

Thanks a lot for your reply, can you help me in having some tutorial which will help me in knowing and understanding use of VOF model..! I am new to CFD, I dont know how to go for this kind of problems. please Help me...!

Thanks once again..!

---sushii.

Hi sushii you can see the tutorial of spining bowl in the manual its very good one for modeling the changing of water level with time step. If you not hve it you can search for it on the web just type VOF tutorial.

hope this help kb

Hi,

Free surface can be applied in two ways. If your problem definintion is of the multiphase then go for the VOF.If not then go for the wall with the zero shear.It will behave like free surface.That is more easier.

Thanks Kb...I will try..for this..!

---sushii..

Hi Tejas..

Thanks a lot for your reply...I know the second option you have suggested, and I hv tried it too...! but now i want to solve the same case with VOF...but i am unable to go for setting up the problem....I really dont know how to go for...! Is it the results are that good with 'zero shear wall' or wall as symmetry BC, as they are with VOF...? is any difference there...? or both are giving similar results..?

---sushii..

sushii what type of your geometry? can you tell me what type of your problem too you wan to simulate with VOF.

Cheers kb

Hi Kb,

My problem is of an anoxic tank...! it is a huge tank 25mX4.5mX3.5m tank...in which upto 3m level water is there...and three small submerged mixers are stirring the whole fluid for mixing it....the water is entering at 52lit/sec from a corner on top and leaving the tank from opposite end through a vertical slit of 1mX3.5m dimension. Now what can be the better way to tackle it out...?

Any help is appreciable...!

---sushii..

Oh i thoght you have a pipe flow like mine I think enabling open channel flow boundary with VOF in your case more suitable try it and compare your results you need just to set the free surface level in the tank.

Cheers kb

Yeah...I am trying...!

Anyway...keep in touch buddy...if possible then mail me at sushilkumar.sonar@gmail.com

Have a nice time...!

Regards, --sushii..

I want to simulate an open channel by FLUENT6.2.16 in 3D model.This channel is rectangular and it's dimentions is: Width=0.2 , depth=0.2 , lenght=10m , the water depth is 0.1m and the average velocity inflow direction is 0.378 .I assume the boundaries by considering :inlet:mass flow inlet , outletressure outlet , up of channelressure outlet. I seperate the boundaries for water and air from Grid - seperate - cell for boundary condition in inlet ,outlet and upper surface of the channel. i choose "open channel flow" and then (free surface level=0.1 , bottom level=0) for each two phase (water and air). for initial condition i consider only the velocity in flow direction (=0.378).I want to know whether my assumption are true or not? I have some more problems who would you please help me . How can we get velocity vectors and contours in cross section?(how can we difine cross section in FLUENT?). Is it possible that the model draw contours only for water(without considering air)? Why can not this model converge?

send your mail to me.i will send you some file.

Hi there....

I hv simulated my problem well...but yet it is not conversed...It is taking lot of time to converge...! Can any one suggest me some tricks to deal with it...? now I have created a free surface with 0.5 as volm fraction of fluid...but I dont know what things to be considered when post-processing this VOF case...!

Please help...!

--Sushii..!

Dear Mr.Tahery This is my email address "rahimy@graduate.uk.ac.ir" Your sincerely

Hi~ I am modling open channel flows by VOF+Open channel flow too.I use two pressure inlets,top one for air and bottom one for water.The single outlet is pressure outlet.But the velocity of water through outlet is fluctuate,can't stay at a normal level.I do not know why.Could you give me some advice? Thanks for the help

Dear Mr.Tahery This is my email address "rahimy@graduate.uk.ac.ir" Your sincerely

I am also interested for free surface flow. Pl. send your files to mdmk27.at.yahoo.com. Thanking you

I am also interested foe free surface flow. can u pls send to me too to kit98192@yahoo.com. Thank you.

[rahulrp]

Mr Taheri,
I am also struck to open channel flow.
Pls do send/share in forum me some test case at praghanmor@gmail.com

Regards
Rahul