Fluids

Fluids

How describe natural convection inside a closed volume

    • giovanni_ianziti
      Subscriber

      hello,


      I`ve a closed volume (heat pipe) with inside a part of water liquid and another part of mixture: air and vapour (when the water is boiling). 


      In my simulation I don`t have a good representation of the convection. the results are similar to the symmetric case but I`m working with a planar case.


      how can I improve the convective movement inside the volume? 


      thank you

    • DrAmine
      Ansys Employee

      1/Work with compressible liquid for liquid and ideal gas for mixture


      2/Apply gravity and set an operating density


      3/More details of your case are really welcome so that we can point to some modifications: detailed screenshot of the problem.


       


      As ANSYS Stuff we won't download or check any attached document.

    • Rob
      Ansys Employee

      Just to add, I don't think compressible liquid has a temperature term for density (check documentation) so if the system has a reasonable gas volume use a polynomial for liquid density. 

    • giovanni_ianziti
      Subscriber


      I`m working with these materials, but I`ve same problems to insert the all mixture properties. I`m using incompressible ideal gas for the mixture with  a pressure of 20000Pa and initial temp of 25 C. the gravity is active.


      thank you

    • Rob
      Ansys Employee

      In a confined space you'll need to use an ideal gas: if the density within the system changes but the volume cannot the solver will struggle.  If you have openings then it's not a problem. 


      However, as you've set water with a constant density you won't see any motion in the water due to natural convection within the water. 

    • giovanni_ianziti
      Subscriber

      In my work I have a non-compressible condition to respect for the flow. Can I lose this condition If I use ideal gas for the mixture?

    • Rob
      Ansys Employee

      Yes. As it's a sealed system something must compress as the mass has to go somewhere. 

Viewing 6 reply threads
  • You must be logged in to reply to this topic.