Buoyancy driven flows
 

Dear community,

I published a new tutorial which is related to buoyancy driven flows. The training case includes the well known run script which will give you all information you need. The case is a solar chimney (imaginary case) in 3D. I simulated just one quarter of the whole design. The driving force in that tutorial is the buoyancy force.

https://holzmann-cfd.de/images/phoca...larChimney.png


Video: https://www.youtube.com/watch?v=mYV18BMr8HY

The can be downloaded from my website https://Holzmann-cfd.de

Questions about the case
 

Hello Tobias,

I want to ask 3 questions about the case please:

1) How did you estimate the mixingLength for k at the inlet in the initial conditions folder?

2) Are you considering photovoltaic panels at the bottom of the rectangle gaps (first attached image)?

3) Why your inlet patch is horizontal and not vertical (second attached image)?

Thanks in advance,
Paul

A) hydraulic diameter
B) yes, it is just a test case without physical condition
C) p-rgh is always easy on horizontal patches.

Hello,

A) Yes, I was trying to calculate with the hydraulic diameter, but for two parallel plates I can't find an equation for Dh. If you have considered the inlet patch as annular diameters, Dh can be easy calculated.

B) Is it because g in p-rgh is distributed on the whole area of the patch, but if you consider as vertical it will be distributed only on a line?

Thanks,
Paul

A) dh = 4A/U

A Area
U perimeter

Hello poulmack,
maybe an addition: two parallel plates have distance d and width w
A=w*d
U=(w+d)*2
so 4A/U=4w*d/(w+d)/2=2*d because w+d=w, d is small compared to w
so dh=2d

hope this helps
Wouter

Radiation
 

Thanks for your answers.

Regarding radiation, a uniform flux in W/m^2 is set in 0/T using externalWallHeatFluxTemperature in the heaterTop. Then in constant/radiationProperies, there are values of absorptivity and emissivity. Does that it mean that the radiation effect covers the whole model or just only the heaterTop? If it is applied to the whole model, how is possible to create different radiation properties each component of the system (for example to the glass in the cover)?

Regards,
Paul