Question regarding applying grid-based solar radiation data to terrain/ground surfaces in FDS

[HEROISCOMING1]

Hi everyone,

I hope you are all doing well.

I am currently using FDS to model micro-meteorological phenomena in an outdoor domain, with a focus on turbulence modeling.

As far as I know, FDS does not natively support setting solar radiation dynamically based on the specific solar altitude/azimuth angle at a given time. To account for shading effects caused by surrounding geometry at a specific time of day, I am planning to use an external solar radiation simulation tool (such as Ladybug or FormIt).

My goal is to extract the grid-by-grid solar flux values for the ground/terrain surfaces from the external tool and map them into my FDS model. (To keep the setup manageable, I am currently focusing only on the ground surface and excluding building facades for now.)

Could anyone share advice or recommended workflows on how to achieve this?

Thank you very much for your time and help!

Best regards,

Pillsoooon

[mcgratta]

By default, FDS treats radiation in the gray gas limit; that is, there is no wavelength dependence. If you were to include the effect of solar radiation, it would only be the thermal/infrared component. Could you just implement either EXTERNAL_FLUX or CONVECTIVE_HEAT_FLUX on the SURF line that defines the ground? The former would represent energy introduced into the computational domain from some external source, i.e. the sun. The latter would change the ground temperature and extract or generate this amount of energy from the air above the ground.