Diffusielijn

Diffusielijn is a Dutch term that translates roughly as diffusion line. In scientific usage it is a generic label for a line or contour that marks the reach or boundary of a diffusing substance after a given period, rather than a fixed technical term with a single, formal definition. The concept is most easily understood from diffusion theory, where the characteristic diffusion distance L after time t in an isotropic medium is often described by L ≈ sqrt(2Dt) (or sqrt(Dt) depending on geometry and conventions). A diffusielijn, in this sense, is a contour around a source at a fixed distance L, illustrating how far diffusion has progressed.

In practice, diffusielijnen appear in various fields as a visual or analytical tool. In materials science and geology they can describe fronts in concentration-depth profiles or diffusion zones within solids, where a line marks the boundary between regions of different concentrations. In environmental science, a diffusielijn may denote the boundary of a diffusive pollutant plume over time, helping to illustrate spread in soils or groundwater. In biology and physiology, similar contours can represent diffusion distances of nutrients or signaling molecules across tissues or membranes.

The term is not universally formalized across disciplines; it is often used descriptively or as a translation for “diffusion line” or “diffusion front” in Dutch-language texts. When used, it typically refers to a contour, boundary, or front associated with a diffusive process, governed in simple cases by Fickian diffusion and diffusion length scales, but applicable with caveats in anisotropic, nonlinear, or complex media.