radiationmodel

Radiation model is a term used across disciplines to describe frameworks for the propagation of radiation, energy, or information. In physics, radiation models describe how electromagnetic radiation travels through space or media and interacts with matter. The core mathematical description is the radiative transfer equation, which accounts for emission, absorption, and scattering along paths. Numerical solutions employ methods such as Monte Carlo ray tracing, discrete ordinates, and diffusion approximations. These models underpin simulations in astrophysics, atmospheric science, optical engineering, and medical physics, where predicting spectra, radiance, or dose is required.

Separately, the radiation model denotes a mobility model used to predict flows between geographic locations. It is characteristically parameter-free and derives flows from the distribution of opportunities and populations, rather than distance alone. In the model, the propensity for travelers from origin i to reach destination j depends on the population at i, the opportunities available at j, and the amount of intervening population around i. It has been applied to explain commuting, migration, and travel patterns across cities and countries, and is often presented as an alternative to gravity-type models that incorporate a distance-decay parameter.

Applications and limitations vary by domain. In physics, radiation models are essential for accurate radiative transfer calculations in complex media. In mobility research, the model offers a parsimonious framework but assumes knowledge of opportunities and may be less accurate in highly heterogeneous or data-sparse regions. See also radiative transfer, diffusion approximation, gravity model, and ray tracing.