Bénard cell

Bénard cells are a pattern of convective rolls that form between two horizontal plates when the lower plate is heated and the upper plate is cooled. This phenomenon occurs when the temperature difference between the plates exceeds a critical value, known as the Rayleigh number.

Convection is the transfer of heat through the movement of a heated fluid, such as air or water. Natural convection happens when fluids expand as they heat up, becoming less dense and rising due to buoyancy. Forced convection involves moving fluids through external means like fans or pumps.

Bénard cells are a macroscopic instability of convection, demonstrating how temperature gradients can drive fluid motion and create organized patterns. This concept is fundamental to understanding heat transfer in various natural and engineered systems.12