Mass transfer is the phrase commonly used in engineering for physical processes which involve molecular and convective transport of atoms and molecules within physical systems. Mass transfer includes both mixing and separation processes.

Some common examples of mass transfer processes are the evaporation of water from a pond to the atmosphere; the diffusion of chemical impurities in lakes, rivers, and oceans from natural or artificial point sources; mass transfer is also responsible for the separation of components in an apparatus such as a distillation column.

Topics:

• Diffusion
• Separation

In astronomy, mass transfer is the process by which matter gravitationally bound to a body, usually a star, fills its Roche lobe and becomes gravitationally bound to a second body, usually a compact object (white dwarf, neutron star or black hole), and is eventually accreted onto it. It is a common phenomenon in binary systems, and may play an important role in some types of supernovae, and pulsars.