# multiphase modelling

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 September 8, 2005, 00:54 multiphase modelling #1 Sumeet Guest   Posts: n/a 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

 September 8, 2005, 01:39 Re: multiphase modelling #2 zxaar Guest   Posts: n/a tutorials are best friends

 September 8, 2005, 02:41 Re: multiphase modelling #3 Mary Guest   Posts: n/a 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 ...

 September 8, 2005, 05:15 Re: multiphase modelling #4 srik Guest   Posts: n/a 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.... Thanks in advance

 September 8, 2005, 06:05 Re: multiphase modelling #5 Mary Guest   Posts: n/a 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.

 September 9, 2005, 01:30 Re: multiphase modelling #6 srik Guest   Posts: n/a 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. Thanks in advance

 September 26, 2005, 02:34 3d cylinder #7 Rashmi Guest   Posts: n/a 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 thanx in advance

 October 9, 2005, 15:06 Re: 3d cylinder #8 Ehab Guest   Posts: n/a 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.

 October 11, 2005, 01:40 Re: 3d cylinder #9 rashmi Guest   Posts: n/a 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

 July 4, 2011, 00:07 #10 New Member   Mridul Join Date: Mar 2011 Location: Melbourne, Australia Posts: 26 Rep Power: 7 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

 December 12, 2014, 07:33 adapt region #11 Member   Muhammed Asmail Join Date: Nov 2009 Location: Iraq Posts: 40 Rep Power: 8 Hi all Please i want to adapt region for 3D clylinder , it has diameter 20mm and length 700 mm what the value of Xmin,Ymin,Zmin and Xmax,Ymax,Zmax and the radius?????when i will go to menu adapt>>region Many Thanks

December 12, 2014, 07:35
#12
Member

Muhammed Asmail
Join Date: Nov 2009
Location: Iraq
Posts: 40
Rep Power: 8
Hi Mary

, it has diameter 20mm and length 700 mm

Many Thanks

Quote:
 Originally Posted by Mary ;124045 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.

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