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August 8, 2000, 11:44 
simulating a twophase flow with an external field

#1 
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hi,
Any advice on the modeling and simulation of a gassolid twophase flow with an exteral magnetic field? Twofluid model or EulerianLagrangian model? By the way, the particles are ferromagnetic. Thanks. Yi 

August 8, 2000, 21:05 
Re: simulating a twophase flow with an external f

#2 
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Hi, I am interested in this problem. I am also reseaching to simulate the twophase flows. Do you have any document about this, please help me!!!! Thank you very much!!!


August 9, 2000, 05:55 
Re: simulating a twophase flow with an external f

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Hi,
EulerianLagrangian model is a classic one but if you want to do simulation with PHOENICS code for exemple I think that you can start with a Twofluid model and look for results. For match informations a bout this problem, you can view documentation of ** US ARMY HEADQUATERS**. 

August 9, 2000, 07:30 
Re: simulating a twophase flow with an external f

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hi, Phan Cong Thuong
I am just curious about the CFD simulation of a twophase flow with not only gravity force but also other external force fields. As mentioned in the first post, an external magnetic field will have big influence on the motion of the ferromagnetice particles in the investigated twophase system. I am wondering what is the main factor to cause the impact. Is it only due to the external force acting on the particles like gravity, or is it also due to the interparticle forces resulting from the external force field? (Suppose the particle diameter is ~1 mm.) This may be easily illustrated using basic knowledge in physics. Unfortunately, I don't know the answer. Frankly speaking, the posted content is not my work. I ever worked on CFD simulation of gassolid twophase flows two years ago. My interest still lies in CFD, though my current work is mostly related with experimental hydrodynamics. As for any documents, I think you will find many references about multiphase CFD in the literature. However, I did not find relevant contributions on my question. If someone knows, I would appreciate very much for any help. Good luck. Yi 

August 9, 2000, 07:37 
Re: simulating a twophase flow with an external f

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hi, there,
Thanks. If possible, I would use CFX or FLUENT. I think the underlying physics determines which model is better to do the job. I like twofluid model, but I have no idea how to use it to simulate a gassolid system in which interparticle forces play an important role. Regards, Yi 

August 9, 2000, 10:16 
Re: simulating a twophase flow with an external f

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I don't know about Fluent, but CFX 4.3 is customizable with user fortran so it can handle just about any type of flow situation if you have the time to write the code. CFX does not have a default model for particleparticle interaction like you described, but a brief review of the available fortran routines shows several that relate to the particle transport model that could possibly be modified to handle your situation.


August 9, 2000, 10:52 
Re: simulating a twophase flow with an external f

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MHD simulation on the two phase system is a difficult topic. As your questioin on the choice of the twofluid model or EulerianLagrangian model, I do not know the exact your system, just some thoughts:
1, Could the second fluid assum to be the continuous phase? (the twofluid model will base on two sets of NS equation) I always get a question: why you use continunity equation for the bubble? (gaslquid plume simulation) 2, How many groups or number particles needed to be calcuated? Then, you can think based on the source of your hardware and software. With limted number of particles, may use EulerianLagrangian. Otherwise, twofluid is good choice. 3, How about the existed results on the Interphase transfer (mass, heat..) in the related fields? The results are about the separated particlefluid or solidfluid. Anyway, you should find the source terms on the phase interaction. Hence, previous theortiecal and experimental results are important. 4, If magnetic forces have effect on both liquid and solid particles, it become more hard by use twofluid simulation since two different source terms should be built in the momentum equation. 5, Will you plan to consider the effect of induced curent? And more..... Hope for the help Sheng it is better first ? 

August 9, 2000, 11:12 
Re: simulating a twophase flow with an external f

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Answer Q1> Twofluid Model (TFM) has been acknowledged as a powerful and efficient tool to simulate complicated multiphase flows, especially for engineering applications, though there are some arguments about the physics of TFM. As you said in Q2, if the number of particles is not large, EulerianLagrangian model would be a good choice. It is possible for me to do both.
Answer Q4,5> That's what I want to know and to consider before starting the simulation. Thanks, Sheng. Yi 

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