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[kavatar]

Hello Everyone,

Can anyone suggest referene papers related to Eulerian Multi-Fluid VOF model available in ANSYS Fluent. I am trying to undrstand the model formulation including governing equations and regime transition detection algorithms (transition from Eulerian to VOF and vice versa).

The theory guide does not provide details about this model and there are very limited number of articles using this model, but these also include very minimal details of the model formulation. 

Kindly suggest related articles so I can understand how this model works.

 

A very good reference article which I found is following. But I am not sure if fluent uses same algorithm (or similar approach). Kindly comment.

Coupling of the Interface Tracking and the Two-Fluid Models for the Simulation of Incompressible Two-Phase Flow by Gregor Cerne, Stojan Petelin, and Iztok Tiselj, Journal of Computational Physics 171, 776–804 (2001). doi:10.1006/jcph.2001.6810

 

I am using Explicit Eulerian Multi-Fluid VOF with Sharp/Dispersed interface modelling option and modified HRIC scheme for volume fraction discretization in my project.

 

Sincerely

Krishna 

[SRP]

Hi,

You can check articles:

Particulate flow modeling in a spiral separator using eulerian multi fluid VOF by Lingguo Meng,shuling Guo.

A 3D, fully Eulerian, VOF solver to study the interaction between the fluids and moving rigid bodies using the fictitious domain method by Ashish Pathak

Hope this helps you.

 

[kavatar]

Hello SRP and other fluent experts,

I have gone through these articles as well as many other papers related to multi-fluid VOF. Ultimately, they led to the paper by Gregor Cerne (doi:10.1006/jcph.2001.6810).

According to this article and the papers suggested by you, in the multi-fluid VOF model, some regions are solved with single velocity formulation (VOF), and in some regions, two-fluid formulation (Eulerin-Eulerin) is applied. These are coupled with a regime transition criteria computed using volume fractions in the neighboring cells. So, if this is true, then the difference between gas and liquid velocity should be zero in single-velocity VOF-applied regions.

I plotted the contours of (gasVelocity-LiquidVelocity) in the computational domain. I found that there is not a single place where the velocity difference between two phases is zero.

My question is that, in the multi-fluid VOF model, does it apply single-velocity VOF formulation in sharp interface regions or not ?(in conjuction with the two-fluid eulerian model in some bubbly regions)

Or it is two-equation eulerian model everywhere, and we call it multiFluid VOF because is uses compressive scheme with varying discretization slope limiter (2 in sharp interface zone and <1 in bubbly zone) in the domain, when in sharp/dispersed option we select phase localized discretization?

Can you flash a light on this point, I need to understand this point before I move forward

Thanks and regards

Krishna 

 

 

[SRP]

Hi,

The multi-fluid VOF model provides a framework to couple the VOF and Eulerian multiphase models. This allows the use of discretization schemes and options suited to both sharp and dispersed interface regimes while overcoming some limitations of the VOF model that arise due to the shared velocity and temperature formulation.This model is only available with the Eulerian multiphase model.

For more details please check fluent theory guide: 14.5. Eulerian Model Theory (ansys.com)

Let me know if you have any question.

[kavatar]

Dear SRP,

Thank you for your time. 

There are two type of papers in the literature using fluent multi-fluid VOF. first set of papers say, it switches between VOF and eulerian while the others say, only two equation formulation is applied everywhere and it is called multi-fluid VOF since special discretiation schemes are used. Overall it's very confusing from the literature.

To resolved this confusion, parallel to this post, I contacted ANSYS team from Pune office. They have clarified this issue. 

Thanks again 

Sincerely

Krishna