Diffusionsöppen

Diffusionsöppen describes a diffusion process where the system is open to exchange with its surroundings, allowing particles to diffuse into and out of the domain. In practice, this means that the boundary of the region of interest is permeable or in contact with an external reservoir, so mass can be transferred rather than being completely confined. The term is used in Swedish contexts to distinguish open boundary diffusion from diffusion in a closed or isolated (diffusionsstängd) system.

In modeling diffusion with diffusionsöppna boundary conditions, the diffusion equation is solved with boundaries that permit exchange with the environment. This can include fixed external concentrations or fluxes that depend on the difference between internal and external concentrations. Open boundaries influence the time evolution of concentration profiles and can prevent artificial buildup that would occur in closed systems.

Applications span materials science, chemistry, and biology. They include diffusion of gases through porous membranes, moisture transport in building materials, nutrient or drug diffusion through tissues, and gas sensing or catalytic systems where exchange with the surroundings is essential. Diffusionsöppna setups are also relevant in packaging and environmental engineering, where external exchange controls performance.

Etymology: diffusionsöppen is a compound in Swedish meaning diffusion-open, used to describe diffusion processes with open boundaries. The term may appear variably across literature, sometimes described by boundary-condition terminology rather than as a stand-alone label.