transportprocesser

Transportprocesser (transport processes) refer to the mechanisms governing the movement of mass, energy and momentum within and between physical systems. They arise from gradients such as concentration, temperature, or velocity and are central to chemistry, physics, engineering, geology, and biology. A unified view treats transport as fluxes driven by these gradients, governed by constitutive relations and boundary conditions.

Mass transport includes diffusion driven by concentration differences and advection by bulk fluid flow. Energy transport encompasses conduction, convection, and radiation. Momentum transport, tied to viscosity, is described by the Navier–Stokes equations. In electrical contexts, charge transport follows Ohm’s law or more general electro-diffusion relations in electrolytes.

Governing equations combine conservation laws with constitutive relations. For example, diffusion is described by the diffusion equation ∂C/∂t = D ∇^2 C; heat transfer by Fourier’s law q = -k ∇T; and fluid flow by the continuity equation ∂ρ/∂t + ∇·(ρv) = 0, with appropriate momentum equations. Modelers use dimensionless numbers such as the Peclet number (advection versus diffusion), the Fourier number (diffusion time scale), and the Damköhler number (reaction versus transport) to classify regimes and guide design and analysis.

Transportprocesser are essential across engineering, environmental science, and physiology, from designing heat exchangers and predicting pollutant dispersion to modeling ion and oxygen transport in tissues and batteries.