Eric,
This has been somewhat fixed--as part of his work with me on a related solver, Henry has implemented a multiphase version of his MULES solver which improves the phase fraction bounding for the multiphase case by several orders of magnitude. I imagine this will be out in future versions of the code. -Kent |
Interesting. Why do you need MULES in a multi-fluid solver, since MULES is typically used to track free surfaces?
Limiting alpha is done in most of the multi-fluid codes with re-normalization of the variable, and enforcement of the mass conservation principle. You can refer to the implementation of codes for nuclear applications like NEPTUNE CFD, or to other multiphase codes like MFIX. Essentially, the idea (from NEPTUNE paper) is to solve for the phase fraction of all the phases, solve for the pressure equation based on total continuity and repeat until 1 - sum(alpha) < epsilon, being epsilon a very small number. In this process some Author re-normalize alpha so that alpha = alpha/sum(alpha) < 1. It is a pretty standard approach, but it is also robust. Best, |
Quote:
|
My bad, sorry. I was misled by the title of the thread!
|
@Kent Did you get the reply to your email?
|
Dear Alberto,
Now I am interested in QMOM and want to do research on this. I find that you have an openSource called OpenQBMM in gitHub. But I could not download it. Could you be so kind send it to me? My email: 981588592@qq.com Regards, Xu |
1 Attachment(s)
Quote:
Dear Alberto, I am working on same solver (twoPhaseEulerFoam) for bubble column. I am Simulating Hills case (1974) for cylindrical bubble column. I am describing my case in detail here. I am running simulations where gas is sparged in the liquid column at superficial velocity of 64 mm/s at the inlet. When the gas rises throughout the column we have some gas hold up and slip velocity for bubbles or actual gas rise velocity at all the axial point in the column. If there is no mass transfer from gas to liquid, that is, no gas dissolved in the liquid, in order to have mass conservation of gas at any axial position in the column, superficial gas velocity (and hence the mass flux of gas) should be same throughout the column and must be equal to 64 mm/s. In other words, (local gas holdup * local bubble rise velocity) must be equal to that of the superficial gas velocity with which gas is entering the column. In order to observe this, I have plotted superficial gas velocity along the axial position in the column as shown in attachment. I have observed that, near inlet (for axial position (Z)<0.1) there is substantial reduction in the superficial velocity of gas, which is an indication of loss of mass for gas in that region. but as we start moving away from the inlet, it is observed that the superficial velocity of gas increases (or recovery of mass of gas) and finally reached the 64 mm/s at Z=0.7 and remains there. I tried to understand this behavior of gas in the column n meanwhile came across this post of yours. I wonder if that is the reason why I have loss of gas near inlet or is there any other reason??. What could be the other possibility? Please help me to get though this. Thanking you... |
BubbleFoam limitations
I want to use bubblefoam solver but it prevents on my work, because of bubblefoam limitations.
BubbleFoam limitations The diameter of the particles constituting the dispersed phase is assumed to be consistent. Aggregation, breakage and coalescence phenomena are not accounted for. What is your suggestion? DO you know any solver uses Euler mixture model ? thank you |
Hi, Alberto.
Recently, I try to use DQMOM method in Fluent to simulate a two-phase flow (water and gas). Because DQMOM method requires three second phases, I set three gas phases. Is this right ? Besides,I don't know how to set the m4 and vof value of three second phases in boundary condition. Best regards. |
BubbleFoam limitations
I want to use bubblefoam solver but it prevents on my work, because of bubblefoam limitations.
BubbleFoam limitations The diameter of the particles constituting the dispersed phase is assumed to be consistent. Aggregation, breakage and coalescence phenomena are not accounted for. What is your suggestion? DO you know any solver uses Euler mixture model ? thank you |
Hi Masoudsh
Which openfoam version are you using? I think bubbleFoam solver is disconinued (though I am not sure) after OF170. look into twoPhaseEulerFoam solver in the recent version of OF (OF231/OF240). Hope it might work for you. All the best |
Hi vishal
thank you from your suggestion. how is multiphaseEulerFoam? Best regard |
Hi masoudsh
Multiphaseeulerfoam can also do your job. But being specific about the solver, it is used when your system has more than two phases in it, for example gas-liquid-solid. Whereas twophaseeulerfoam is used only for two phase systems. With kind regards |
masoudsh,
I am no expert in this area, but have you considered the IATE diameter model in twoPhaseEulerFoam (i.e., recent OF, not Foam-ext)? If you don't need to resolve individual tiny bubbles, but want to keep track of bubble surface area, for example, it is an elegant solution. IATE accounts for bubble breakage, coalescence due to wake, etc. At the other end of the scale, interFoam (incompressible) is useful for looking at individual bubbles if incompressibility isn't an issue (small pressure/depth gradient), but the grid must be much smaller than the smallest bubble. |
hello
what is IATE? is it in twoPhaseEulerFoam? thank you for reply to my question |
IATE is "interfacial area transport equation"
Yes, it is available in twoPhaseEulerFoam. See tutorials > multiphase > twoPhaseEulerFoam > laminar > bubbleColumnIATE and study the constant > phaseProperties file. IATE will also require the kappa.* and Theta.* files in the 0 folder, and a few other considerations (e.g., thermophysicals) depending on the model assumptions. So far, it seems to be fairly realistic for air/water. |
thank you for reply
|
All times are GMT -4. The time now is 02:46. |