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-   -   multiphase modelling (http://www.cfd-online.com/Forums/fluent/37832-multiphase-modelling.html)

 Sumeet September 8, 2005 00:54

multiphase modelling

can anybody please guide me in multiphase modelling. i have to model water in square container heated and there is air above the surface . basically i have to generate the interface . pls suggest some model with the outline of procedure as well.

thank u, sumeet

 zxaar September 8, 2005 01:39

Re: multiphase modelling

tutorials are best friends

 Mary September 8, 2005 02:41

Re: multiphase modelling

VOLUME OF FLUID is the model you should use. You have to define two phases: air (primary phase) and water In Operating conditions of course you have to include gravity, operating pressure is 101325 Pa (if container is opened to atmosphere) and don't forget to specify reference pressure location

I hope it helps ...

 srik September 8, 2005 05:15

Re: multiphase modelling

Hi, I am also trying similar type of problem. An rectangular open channel with water and air. I could not find any fluent tutorials related to open channel flow. Can anyone suggest right BC for open channel flow and any sample cases run on fluent....

 Mary September 8, 2005 06:05

Re: multiphase modelling

OPEN CHANELL FLOW. One BC is above air - define it as pressure-inlet, name:OPEN And of course another two BC are velocity inlet (name-INLET) and pressure outlet (name-OUTLET)(defined as the whole area of chanell) and wall of the chanell of course. FLUENT: Multiphase model - Volume of fluid Number of phases: 2 (air and liquid water) Define materials- add water liquid Define Phases- Phase 1 (AIR) and Phase (2) (water-liquid) Define operating conditions- include gravity check Specified operating density Operating pressure 101325 and reference pressure location -give exactly the coordiantes of one point on the BC (OPEN) Be carefull when you initialize. After that you sholud patch, d.h. Adapt-Region (in order to make register where the air is-you have 3 shapes), this is important - hier you mark the region where is air. And then Solve-Initialize-Patch (now you have your register) select the register, write the volume fraction of phase 2 (water-liquid) it is 0 (now you defined where is the air)and click Patch. And then try to iterate ... etc.

 srik September 9, 2005 01:30

Re: multiphase modelling

Hi, Thank you very much for the suggestions. I am able to simulate open channel with VOF Method using the above conditions. But I am unable to simulate the same problem using "open channel" option in VOF method. I am using mass-flow-inlet condition in which only free surface level need to be specified, pressure outlet condition in which free-surface level has to be specified and top boundary which, I am specifying as symmetry, since specifying top as pressure inlet is causing divergence. I am patching the water phase using adapt-region and initialize-patch. The problem I am facing is the water level in the domain is increasing above the free-surface level specified.

 Rashmi September 26, 2005 02:34

3d cylinder

hello everyone

plz let me knw if anyone knows how to create 3d cylindrical pipe with structured meshing..i want to transform the cylinder to mappable...plz explain

 Ehab October 9, 2005 15:06

Re: 3d cylinder

Hi Rashmi, Did you find out how to solve this problem. I have the same one, I'm simulating a liquid flow from a circular tank via a horizontal narrow and short pipe to the atmosphere. I'm trying to capture the liquid surface using VOF (unsteady formulation). I'm having difficulty and have been told the mesh should be structured while I'm using unstructured one.

So, please, if you have know how, let me know.

Thanks.

 rashmi October 11, 2005 01:40

Re: 3d cylinder

hi sorry for delay as i was not well.......... if u want to create structured meshing then u shud do it by virtual edge split and face split operations....

first create a 3d cylinder and split the edges of the cylinder with point equally with edges virtual connected and then split the face (ie the whole face).then u can mesh the cylinder by map scheme.then mash the whole volume my cooper..the vol created will be virtual so after meshing u can transform the volume into real.

hope this will help u good luck rashmi

 makkks July 4, 2011 00:07

Hi guys,

similar problem but with oil and air.
closed fin with oil running thru and air blowing on top.
I have defined two diff domains in CFX-pre: AIR and OIL.
In basic settings where we have to define Fluid and particle definitions , I have added oil and Air .
The problem I am facing is to define "Buoyant Reference Density"...
I am not able to separately define thr densities...Its only taking 1 density at a tym.
Ref den of air- 1.185
Ref den of oil - 830.33
as soon as i put 1.185 for air , oil density turns into 1.185.

Thanks for help :)

 Muhammed_iraq December 12, 2014 07:33

Hi all

, it has diameter 20mm and length 700 mm

Many Thanks

 Muhammed_iraq December 12, 2014 07:35

Hi Mary