The Boussinesq Approximation

The Boussinesq approximation is a simplifying assumption used in fluid dynamics, especially for studying how fluids like air or water move when temperature differences cause density changes. It assumes that variations in density are negligible except when they create buoyancy forces—those that make warm fluid rise and cool fluid sink. This approximation allows scientists to analyze fluid flow more efficiently without solving complex equations that account for tiny density changes everywhere, making it easier to understand phenomena like natural convection, ocean currents, or weather patterns while maintaining accurate predictions of the main flow behavior.