Learning Forum

[douniaextra1]

Hello everyone,

my study case is transient natural convection in which I'm using boussinisq density in air property, the problem is in the thermal expansion coefficient.

• I search online, and I found a value of 0.0032 (1/k) for air.


• but I found a tutorial video in YouTube that use 0.036 (1/k),


• when I'm using a value of 0.00032(1/k) I found good results.

so my question is is it logical if I use 0.00032 ? 

and how can I know the right value in my case?

I'll be so grateful for any comments or answers.

Best wishes,

Dounia

[sathya]

Hi,

I think the issue is with units system followed.

Kindly verify the units in all the 3 sources.

Select and apply the unit system as per your setup.

[douniaextra1]

Hi sathya Actually, they all have the same unit (1/k).
Best wishes
Dounia

[Rob]

You need to figure out the correct value, it's not something we can help with.  As a check do the maths with the various coefficients and then review the ideal gas model (fix P) to see how the density changes. How do all the values compare?