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Yplus calculation for buoyant flow

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Old   December 19, 2017, 09:51
Default Yplus calculation for buoyant flow
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Rajesh
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Hello,
I have to refine mesh near wall in a natural convection case and the y plus should between 30 and 300. but in the buoyant case my internal fluid has initial conditions of velocity as (0 0 0).

How can I calculate y plus with zero velocity in the domain?

The flow should pass from hot wall to cold wall.

Thank you
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Old   December 19, 2017, 10:14
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You could calculate y+ for u=0 (it will be 0) but you should not.
Y+ is only interesting for the final solution, not for the initial conditions.
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Old   December 19, 2017, 11:29
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Filippo Maria Denaro
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You could use the characteristic bouyancy velocity, that one that gives you the Rayleigh number of your problem.
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Old   December 19, 2017, 18:29
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Thank you for the reply guys,

I was given a closed room geometry with an air-conditioner attached to one of the walls. and gave an outside temp to be 50degree Centigrades and coefficent of heat transfer is 0.5 W/(m^2 K) for walls.

asked to setup yplus between 30 and 300
and correct choice of turbulence model and its parameters.

Should I give any inlet velocity at AC vents and outlet pressures? or the air in the room has zero velocity without any inlet velocity.

I am new to simulating with energy equation included. Any references to read can be greatly helpful.
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