System and methods are disclosed in connection with a reaction at or below the surface of a work object, in the context of a fluid flow fostering the reaction. In some example embodiments, the reaction is fostered by (1) creating fluid flow of an inerting fluid over a surface during exposure of the surface to a predetermined type of light, (2) creating fluid flow comprising a reactive species that reacts with another species at or below the work surface in a predetermined manner and/or (3) creating a fluid flow comprising a catalytic species that catalyzes a reaction in a predetermined manner, e.g., during exposure of the surface to a predetermined type of light. In some example embodiments, a light source is employed that comprises a solid-state light source, e.g., a dense array of solid-state light sources. In at least one of such example embodiments, the reaction is a photoreaction associated with the light source.