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thermal expansion coefficient in FLUENT

    • douniaextra1

      Hello everyone,

      my study case is transient natural convection in which I'm using boussinisq density in air property, the problem is in the thermal expansion coefficient.

      • I search online, and I found a value of 0.0032 (1/k) for air.

      • but I found a tutorial video in YouTube that use 0.036 (1/k),

      • when I'm using a value of 0.00032(1/k) I found good results.

      so my question is is it logical if I use 0.00032 ? 

      and how can I know the right value in my case?

      I'll be so grateful for any comments or answers.

      Best wishes,


    • sathya


      I think the issue is with units system followed.

      Kindly verify the units in all the 3 sources.

      Select and apply the unit system as per your setup.

    • douniaextra1
      Hi sathya Actually, they all have the same unit (1/k).
      Best wishes
    • Rob
      Ansys Employee

      You need to figure out the correct value, it's not something we can help with.  As a check do the maths with the various coefficients and then review the ideal gas model (fix P) to see how the density changes. How do all the values compare? 

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