Advection

In physics and fluid dynamics, advection refers to the transport of a substance, such as a fluid, a gas, or a solute, by the bulk motion of the medium it is in. This transport can be caused by a variety of factors, such as the movement of air or water currents, or the flow of a chemical solution through a pipe.

Advection is distinct from diffusion, which is the movement of particles from an area of high concentration to an area of low concentration due to random thermal motion, and from convection, which is the transfer of heat by the movement of a fluid.

In mathematical modeling of fluid dynamics, advection is often described by the advection equation, which is a partial differential equation that relates the rate of change of a quantity with respect to time and position to the velocity of the fluid. Advection plays an important role in many physical phenomena, such as weather patterns, ocean currents, and the spread of pollutants in the atmosphere or in waterways.