Non-Equilibrium Thermodynamics

Non-equilibrium thermodynamics is a branch of physics that deals with the behavior of systems that are not at equilibrium, meaning that the system is not at rest. In contrast, equilibrium thermodynamics deals with systems that are in a state of balance, where all processes are happening at the same rate and the properties of the system do not change over time.

Non-equilibrium thermodynamics is concerned with the transfer of energy and matter within a system, and how these transfers affect the behavior of the system. This can include the movement of heat, mass, and energy within a system, as well as chemical reactions and phase transitions.

One of the key concepts in non-equilibrium thermodynamics is the concept of flux. Flux refers to the rate at which energy or matter is flowing through a system. In non-equilibrium systems, the fluxes of energy and matter are not constant, and this can lead to a variety of interesting phenomena, such as phase transitions, chemical reactions, and the creation of complex structures.

Non-equilibrium thermodynamics is important in a wide range of fields, including physics, chemistry, and materials science. It is used to understand the behavior of systems that are not in equilibrium, such as in the study of transport phenomenaA field of engineering that studies mass, energy, and momentum within and between systems, such as heat and mass transfer, chemical reactions and biological systems.

One of the most important developments in non-equilibrium thermodynamics is the Onsager reciprocal relations, which provide a theoretical framework for understanding transport phenomena, such as the relationship between heat and mass transfer.