natural convection

[Michele1980]

Hello to all,

I would like to have some clarifications how to set up correctly a natural convection case.
By reading tutorial "Transient flow and heat equations – Rayleigh-Benard instability", I see that on heat equat. tab it's imposed to set:
convenction = computed;
I think this is to say to Elmer that density change according to the temperature.

Why gravity is not specified too (example on body forces tab, imposing F2= -9.81 m/^2, y direction)? How elmer recognize it?
Is there a possibility to see variables of calculation? and how to set up new ones?

Thanks a lot

Regards

[Supituki]

Hi Michelle,

I found this case.sif file among the different examples that are stored at the "tests" elmer folder. The test is called "Natural Convection".
In it you can see how the gravity is defined.


Regarding to the natural convection problem, I was wondering if it is possible to define the convection coefficient at the boundaries myself. Instead of modelling a bar and the air surrounding it, I would like to just create the bar and impose the h convection coefficient. I have read many posts but I have not found any example in which the h coefficient is inserted manually. Basically the case is that I want to define a Neumann boundary condition, am I correct?

Kind regards,

Supituki

[cemg]

Hi Supituki,

Elmer Models manual, p.17: http://www.nic.funet.fi/pub/sci/physics ... Manual.pdf

Regards,

Cesar

[Supituki]

Upssss

Thank you very much for your help!