dissipationrate
Dissipation rate is the rate at which energy is irreversibly lost from a system and converted into heat by dissipative processes such as viscosity, thermal conduction, or friction. It is a key concept in thermodynamics and fluid dynamics for describing how stored or transported energy diminishes over time.
In turbulence, the dissipation rate per unit mass, often denoted ε, represents how quickly turbulent kinetic energy
The concept also appears in other contexts. Per unit volume, the viscous dissipation rate is Φ = 2μ
Measurement and estimation of dissipation rate can be experimental, via velocity field measurements and structure functions,