boussinesq approximation when temperature difference is large
 

I'm studying on the natural convection of spent fuel in the dry storage system.

I understand that boussinesq approximation can be used only when the temperature difference is small.

If the temperature range is 300K-500K for example, is it right to simply use an incompressible ideagl gas law that uses the p=rho*R*T law?

Or can i just use the boussinesq approximation?

i don't know about these.


Thank your reply.

That temperature range is too large for Boussinesq. I've heard 10% density difference maximum. Ideal gas is not incompressible, it is definitely compressible, and using that for density would be much more appropriate.

Thankyou so much!

Hi evcelica,
I have a doubt regarding coefficient of thermal expansion which we use in boussinesq approximation.
I am doing simulation for natural convection for a pcb in an enclosure. the freestream temp is 322K. i read bousinesq approximation is valid iff
beta * (T-T_ref) <0.05. in this for beta what should I consider. my fluid is air and as its an ideal gas beta = 1/T. so here what temperature should I use.

Thanks for the help