[Ariya]

Hi Guys,

Considering a natural Convection problem (Steady State, Pressure-Based).I wonder if anyone knows what is the best value of the following factors in Pressure-Inlet Boundary Condition for Air at 20° C in a box with ∆T = 10° C ( T top –T bottom) at.

• Turbulent Intensity
• Turbulent Viscosity Ratio

OR

What is best value for K and Ɛ ?
Cheers,

[skikay]

Originally Posted by Ariya

Hi Guys,

Considering a natural Convection problem (Steady State, Pressure-Based).I wonder if anyone knows what is the best value of the following factors in Pressure-Inlet Boundary Condition for Air at 20° C in a box with ∆T = 10° C ( T top –T bottom) at.

• Turbulent Intensity
• Turbulent Viscosity Ratio

OR

What is best value for K and Ɛ ?
Cheers,

it is difficult to compute,because you could not know I and Re,so you can assume the average velocity(4e-4) and I(4%).by computing,we could define K and Ɛ!
of course ,it takes many time to verify！

[nikhil]

It does not have to be exact. You can also use the option of intensity and hydraulic diameter.
For intensity you can mention 5% for the not highly turbulent flow (guess on the basis of upstrem condition of flow domain) and 10% for highly turbulent flow.

You can easily compute the hydraulic diameter based from the geometry features,

[Ariya]

Thanks So much guys, your solotions are reaseonble and worked for me