dynamic mesh for porous media combustion?

Hi , all,

I am doing a project of porous media combustion with fluent. The application of this project is diesel particle filter which is used on diesel vehicles. I am just starting this project. Therefore I want to ask a very general question of this project. Below is the 2D geometry of this project:

The red region is soot cake which is a porous media and there is also soot in the porous wall the filter. My purpose is to simulate the combustion process of soot cake and soot trapped in the porous wall. The initial soot cake thickness is given and drawn as porous region. The local soot concentration in soot cake and porous wall is defined as an UDS. 

The whole process is like air flows through the porous zone and reacts with soot cake during which soot cake is consumed until no soot left. My question is do I need to use dynamic mesh to describe the variation of soot cake region? My thought is dynamic mesh is not need for this case. Because local soot mass concentration is a variable to define whether this region is a porous region. To be specific, when local soot mass concentration is 0, the porosity of this cell is 1 and becomes non-porous. On the contrary, as long as the local soot mass is not 0, the region remains a porous media zone.

I am posting this thread to validate my thought. Anyone who are doing similar project? Please help.

Best regards.

Weiqiang 

Comments

  • Weiqiang LiuWeiqiang Liu Member
    edited May 2019

    I have this confusion because I found a similar tutorial case in Comsol and dynamic mesh is used in that case. I wonder if dynamic mesh is needed for fluent.

  • RobRob UKForum Coordinator
    edited May 2019

    No need for dynamic mesh, porous media & UDFs should cover it all. 

    Unfortunately we're unable to offer detailed "engineering" suggestions because of the export rules: I have seen this done before. 

  • Weiqiang LiuWeiqiang Liu Member
    edited May 2019

    Do you mean you've seen somebody else posted similar thread? 

    Thanks very much! You give me confidence.

    Best regards.

    Weiqiang

  • Weiqiang LiuWeiqiang Liu Member
    edited June 7

    Hi, Rwoolhou,

    I've done this project for almost one year. Still I can not reproduce results in literature very accurately. I finished all the UDFs and porous media model in fluent. The maximum temperature and soot concentration profiles are very similar to literature. However, I can not get the even-close y velocity contour like the author did. The author has very obvious y velocity at end of the channel while I don't. The very small y velocity at the corner makes heat accumulate and divergence happened. 

    I tried to use compaction model in the simulation which is a UDF code to calculate soot concentration exchange between upper and lower cells. However, it does not work. You mentioned you've seen this done before. Could you please give me some hints or suggestions? My email is [email protected]

    I put the y velocity contour the author obtained with very obvious y velocity at end of the channel below

    please help

    Weiqiang  

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