Multizone Blocking Decomposition failed.

I am a beginner to Ansys Fluent. I am trying to mesh a microchannel heat exchanger as part of my project. But i couldn't do the meshing part. It shows an error "MultiZone blocking decomposition failed".

I have modeled the geometry using Ansys Spaceclaim. I have attached the Archive file along. Please help me.


  • peteroznewmanpeteroznewman Member
    edited March 29

    Replace the Multizone method with Hex Dominant method.  On the Mesh Details window, type 2.5e-2 mm for the Element Size and you will get a hex mesh.  That works in this case, but in general, never use Hex Dominant for CFD meshes because it can create horrible element shapes in the center, where you can't see them. This is not a problem for Structural solvers but is poison for CFD solvers.

    Three elements across a fluid channel is way too few to properly compute the flow. You will want at least 10 elements across the channel and smaller elements near the wall.

    Regards, Peter

  • kkanadekkanade Forum Coordinator
    edited January 2019

    following link may help you. 

    if this helps you, please mark this post as 'is solution' to help others on forum.




  • jaseemharryjaseemharry Member
    edited February 2019

    Thank you for the reply. and sorry i took so long. I was busy with my project.

  • ZIcoZIco Member
    edited March 28


    I am facing mesh problem and the generated mesh is not so smooth. i am using Multizone method with edge sizing and face mesh.

    Please check the attachment for reference and help me to generate smooth mesh.



  • kkanadekkanade Forum Coordinator
    edited March 30

    you may need to use some edge sizing. 

    as this was about failed multizone and is marked as 'is solution' , can you please create a new post in meshing to improve mesh. 




    If this helps, please mark this post as 'Is Solution' to help others.

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  • ZIcoZIco Member
    edited March 30
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