passive scalar boundaries

ultrich

Hi

I work with both, active & passive scalars. I have been able to define boundaries (baffle) that are impermeable to mass flow and at the same time allow diffusion. However I have not been able to define a boundary that can allow mass flow and zero flux for some chosen scalars; in my case, these are solved only by diffusion. When I define walls, the GUI clearly says that there is a zero flux restriction for these scalars but it is not true them freely to diffuse, even if you define it not to. But then again, I may be doing something wrong. Do you know how to define a boundary that allows mass flux and 0 flux only for some scalars?

Many thanks

Ul