tank drainage on fluent

piyusharas · June 24, 2015, 04:44

Suppose I have a tank which is half full of water initially with one exit at bottom surface and one inlet on upper surface . Tank is kept in atmosphere and now I have to analyse the system on fluent . Will I have to use multiphase model??
If yes why and if no then why not?
I am very much confused as my domain inside tank I have taken it as water but it is not totally filled with water. Will it automatically assume vaccum in rest of space or I have to mention.
Please help

edoan · June 24, 2015, 16:05

It will not initialize a vacuum, when you do the initialization the whole domain will be filled. For your case I suggest VOF multiphase method.

piyusharas · June 24, 2015, 16:07

I urgently need some examples of vof model . I cant get it on net. Can you please tell me where will i get some tutorials or examples .
If you have something then please mail me piyusharas.iitkgp@gmail.com

piyusharas · June 27, 2015, 18:56

I am working on a multiphase VOF model
It is kind of tank drainage with one inlet and 6 outlets.
I am done with everything till Adapt-> Region and Solution Initialization -> Patch .
This to things I skipped and after running I am getting error as

Global courant number is greater than 250.00 The
velocity field is probably diverging. Please check the solution
and reduce the time-step if necessary.

What should I do .Please help.
here is how my model look
https://drive.google.com/file/d/0B9c...ew?usp=sharing

edoan · June 29, 2015, 07:50

is the domain initially completely filled with water? is the error happening right away or after some time? what is your timestep?

piyusharas · June 29, 2015, 07:54

Sorry the screenshot I have given is a little wrong as I am talking about steady state so now I am working on steady instead of transient.
I am working on both low and high flow rates but in both flow rate is not that much that it can fill the complete fluid domain with water i.e. air is also present in steady condition.

edoan · June 29, 2015, 08:45

so you do or don't initialize the air with a patch initialization? sorry i didn't understand your meaning

piyusharas · June 29, 2015, 12:20

Actually I have not worked on multiphase earlier that's why i might have left some steps.
Yes I have done nothing like initializing patch of air.
please tell me some basic steps of how to setup my model in fluent.

Need help .

Thank You

edoan · June 29, 2015, 15:34

i responded to your PM

June 24, 2015, 04:44	tank drainage on fluent	#1
piyusharas Member Piyush Aras Join Date: Jun 2015 Posts: 34 Rep Power: 10	Suppose I have a tank which is half full of water initially with one exit at bottom surface and one inlet on upper surface . Tank is kept in atmosphere and now I have to analyse the system on fluent . Will I have to use multiphase model?? If yes why and if no then why not? I am very much confused as my domain inside tank I have taken it as water but it is not totally filled with water. Will it automatically assume vaccum in rest of space or I have to mention. Please help

June 27, 2015, 18:56	VOF model	#4
piyusharas Member Piyush Aras Join Date: Jun 2015 Posts: 34 Rep Power: 10	I am working on a multiphase VOF model It is kind of tank drainage with one inlet and 6 outlets. I am done with everything till Adapt-> Region and Solution Initialization -> Patch . This to things I skipped and after running I am getting error as Global courant number is greater than 250.00 The velocity field is probably diverging. Please check the solution and reduce the time-step if necessary. What should I do .Please help. here is how my model look https://drive.google.com/file/d/0B9c...ew?usp=sharing

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June 24, 2015, 16:05		#2
edoan Member Ethan Doan Join Date: Oct 2012 Location: Canada Posts: 90 Rep Power: 13	It will not initialize a vacuum, when you do the initialization the whole domain will be filled. For your case I suggest VOF multiphase method.

June 24, 2015, 16:07		#3
piyusharas Member Piyush Aras Join Date: Jun 2015 Posts: 34 Rep Power: 10	I urgently need some examples of vof model . I cant get it on net. Can you please tell me where will i get some tutorials or examples . If you have something then please mail me piyusharas.iitkgp@gmail.com

June 29, 2015, 07:50		#5
edoan Member Ethan Doan Join Date: Oct 2012 Location: Canada Posts: 90 Rep Power: 13	is the domain initially completely filled with water? is the error happening right away or after some time? what is your timestep?

June 29, 2015, 07:54		#6
piyusharas Member Piyush Aras Join Date: Jun 2015 Posts: 34 Rep Power: 10	Sorry the screenshot I have given is a little wrong as I am talking about steady state so now I am working on steady instead of transient. I am working on both low and high flow rates but in both flow rate is not that much that it can fill the complete fluid domain with water i.e. air is also present in steady condition.

June 29, 2015, 08:45		#7
edoan Member Ethan Doan Join Date: Oct 2012 Location: Canada Posts: 90 Rep Power: 13	so you do or don't initialize the air with a patch initialization? sorry i didn't understand your meaning

June 29, 2015, 12:20		#8
piyusharas Member Piyush Aras Join Date: Jun 2015 Posts: 34 Rep Power: 10	Actually I have not worked on multiphase earlier that's why i might have left some steps. Yes I have done nothing like initializing patch of air. please tell me some basic steps of how to setup my model in fluent. Need help . Thank You

June 29, 2015, 15:34		#9
edoan Member Ethan Doan Join Date: Oct 2012 Location: Canada Posts: 90 Rep Power: 13	i responded to your PM