# HOW to define boundary conditions in DPM?

 Register Blogs Members List Search Today's Posts Mark Forums Read

 May 29, 2003, 21:36 HOW to define boundary conditions in DPM? #1 x.p.lee Guest   Posts: n/a Hello to all The gas bubbles induced liquid flow field in a water tank is to be calculated in my model. I got a problem in my calculation using DPM, that is i have to define the face(3d) or edge(2d) adjacent to the injections(randomly distributed on the face or edge)as a wall zone. But in this case, i don't know how to define its boundary conditions, since the injection is the only flow inlet, with a face or edge of the tank open to the air, without the flow outlet. the injiection particle is assumed to be bubbles of air with a fixed diameter.As the bubbles rise along the face or edge because of buoyancy, the continuous phase(water here)will be dragged to form a flow field in the tank. how to define the boundary conditions? how to initialize the calculation with the gas bubbles? Any help will be appreciated!

 May 30, 2003, 00:36 Re: HOW to define boundary conditions in DPM? #2 Alex Munoz Guest   Posts: n/a Hi I was thinking in you case. In my opinion, the only way to estimate the flow field is applying multiphase models, because the Discrete Phase Model was developed under the assumption of low volume fraction (less than 12% DP/CP). I guess you require a volume fraction higher than 12% to provide at least a gentle mixing. Even if you were able to use the discrete model available in fluent, you need a model for the continuous phase and none of them would give you a satisfactory answer. The best model to simmulate mixing in tanks is the LES, however this model is incompatible with the DPM. Therefore, you should talk to someone in this forum about the potential to use LES and multiphase models for your case. Unfortunately, I have never worked with multiphase model, so I cannot give you a better insight. Best regards Alex Munoz

 May 30, 2003, 04:01 Re: HOW to define boundary conditions in DPM? #3 x.p.lee Guest   Posts: n/a Hi, Alex Munoz Thanks for your reply! In my model the volume fraction of the dispersed phase is about 10%, so i want to use DPM. The problem you mentioned above do exist, it's not easy to find a model for the continuous phase. I am not so familiar with the LES and Multphase model either. i will start to learn them. thanks again for your advice! best regards X.P.Lee

 May 31, 2003, 03:26 Re: HOW to define boundary conditions in DPM? #4 winnie Guest   Posts: n/a Hi, my friend I think maybe you can define the face(3d) or edge(2d) adjacent to the injections(randomly distributed on the face or edge)as velocity inlet condition and set the velocity equal to zero. Then you can initialize the field using inlet zone, then you give the initial field with zero velocity everywhere. Since I am not familiar with your problem, I don't know whether my advice is useful. Good luck! winnie

 May 31, 2003, 09:12 Re: HOW to define boundary conditions in DPM? #5 x.p.lee Guest   Posts: n/a Hi, Winnie Thanks a lot! That's a good idea, i will try it! Thanks! X.P.Lee

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Attesz CFX 7 January 5, 2013 04:32 almir OpenFOAM 3 September 27, 2011 02:20 Fan Main CFD Forum 10 September 9, 2006 12:24 Dan CFX 0 April 3, 2006 11:32 Sheenu Main CFD Forum 4 May 12, 2000 12:52

All times are GMT -4. The time now is 14:12.