Fickiaanse

Fickiaanse is a term used in Dutch-language science to describe diffusion that follows the laws of Fick. The term derives from Adolf Fick, a 19th-century German physician who formulated what are now known as Fick's laws of diffusion. In this sense, 'Fickiaanse' refers to processes in which the diffusive flux is proportional to the negative gradient of concentration, so that J = -D ∇C, with D as the diffusion coefficient.

Under the common assumption of constant D in a homogeneous medium, Fick's first law applies to steady-state diffusion, while Fick's second law governs time-dependent diffusion: ∂C/∂t = D ∇^2 C. The term is widely used in chemistry, physics, biology, and materials science, for example in modeling pollutant transport in air and water, nutrient diffusion in tissues, or drug release from polymers.

Fickiaanse diffusion presumes no memory effects and no coupling to reactions or mechanical deformation. In many real systems, diffusion deviates from Fick's law, producing non-Fickiaanse or anomalous diffusion, where D may depend on C or t, or where transport is constrained by viscoelastic media or obstacles.

Etymology and usage: the term honors Adolf Eugen Fick (1829–1901), with the Dutch adjective 'Fickiaanse' used to describe phenomena rooted in his laws. The use of the term is most common in Dutch-language texts and may be encountered as 'Fickian' or 'Fickian diffusion' in English-language literature.