Heat loss

I've been setting up a steady flow transient transport model to calculate tempertaures in soil surrounding an electrically heated plot where the temperature is controlled and known (changes with time) at different depths. I apply these temperatures within the plot with time varying border conditions. I have set no fluxes in or out.

Will Feflow calculate loss of heat up through the top slice and down through the bottom slice in my model ?? or are these considered no flux boundaries ??.

Best regards Christian

By default, these are no-flux boundaries. I recommend to use - for example - a third-kind boundary condition on top with a reference (air) temperature and some transfer rate (being the inverse of the transfer resistance).

Thanks a lot. I thought these boundaries were no-flux but could not find it stated directly anywhere. Probably didnt look enough.  My scenario is a bit special as the surface is actually insulated (with mats) and also hot air is drawn from the vadoze zone by vacuum so its a bit complicated and i dont have all details. But at the moment I'm not supposed to describe this in detail.  If I have to at a later stage I can use the approach you've suggested. Thanks again.