solar heating

[c3109396]

Hi,

I'm currently modelling solar heating of a model house. To do it in CFD you have to create an external environment. As a result this does not allow a transparent boundary condition to be applied to internal objects (my window on the house).

Is there a way to model a window when it is within the external environment?

I've tried changing the transmissivity value in the material properties, however, I still have had no success getting any solar radiation or heat passing through the window to the slab.

Cheers,

Jackson

[apolo_vanderberg · Accepted solution]

You will need to use Transparent materials.
Given that some of our inherent assumptions are based on diffuse grey body radiation.

As solar energy comes in to the domain you will see the outer face of the window heat up based on its emissivity.
Given the windows transmissivity, that percentage will then be radiated (diffusely) from the inner face of the windows.
You will get the appropriate amount of energy in to the interior domain, however, if what you were looking for was that the solar energy would heat a small patch on the interior (in the shape and direction of the window) that is not how the diffuse grey body assumptions work.

[c3109396]

Hi,

Thanks for the response. I've modelled it how you said.

In regards to this comment you made (see below).

"if what you were looking for was that the solar energy would heat a small patch on the interior (in the shape and direction of the window) that is not how the diffuse grey body assumptions work".

Are you saying I shouldn't expect any solar heat flux to pass through the window to the slab but I should get an increased temperature on the interior slab in the shape and direction of the window shouldn't I?

I did get a slight increase in temperature on the slab, however, I expected more. I used an emissivity = 0.3 and trnsmissivity = 0.7 as an initial try. The glass volume is 6.38mm thick. Do you have any particular values you recommend for this simulation or are these okay?

Thanks again,

Jackson

[Royce_adsk]

Hi Jackson,

Basically what Apolo said is that you won't see a hot spot where the sun would be hitting the floor on the other side (inside the house) of the window. Instead, the heat will be spread out (diffused/non-directional influence) throughout the entire room.