How do I decide between laminar or turbulent modeling in case of the thermal management of an electronic box (or similar) where fluid motion is driven only by convective fluxes? Re number doesn't seem to be useful. What about Grashof number? Thanks

well generally in natural convection problems, the flow is driven by thermal energy, so as there is no momentum-driven flow, you can use either laminar or turbolent assumptions.

Calculate the Rayleigh Number (=GrPr), the transition value from laminar to turbulent is given in heat transfer textbooks.

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[lyes43]

hey ahmed I'm new user of FLUENT and GAMBIt and I 'm working on simulation of mixed convection in a rectangular horizontal channel contain heat sources ex electronic compounents maybe u help me to simulate that problem using any Code or program
i have expirimental results to valid my results
waiting ur reply thx. lyes43@yahoo.com