Definition and Examples of Dissipation
– Dissipation is the result of an irreversible process that affects a thermodynamic system.
– In a dissipative process, energy transforms from an initial form to a final form with reduced capacity for thermodynamic work.
– Dissipation occurs in processes such as heat transfer, fluid flow, diffusion, chemical reactions, and electric current flow.
– Dissipative thermodynamic processes produce entropy.
– Friction is a prime example of an irreversible thermodynamic process.
– In hydraulic engineering, dissipation occurs when the mechanical energy of flowing water is converted into thermal and acoustical energy.
– Irreversible processes such as heat flow, fluid flow, diffusion, chemical reactions, and electrical current flow involve dissipation.
– Lord Kelvin identified friction, diffusion, conduction of heat, and absorption of light as examples of dissipative processes.
– The concept of dissipation was introduced by Lord Kelvin in 1852.
Energy Dissipation
– The conversion of mechanical energy into heat is called energy dissipation.
– Energy dissipation can occur in electric and electronic circuits due to the generation of unwanted heat.
– Dissipation leads to an increase in entropy.
Computational Physics
– Numerical dissipation, also known as numerical diffusion, can occur in computational physics when solving differential equations.
– Numerical dissipation can reduce the energy of an initial wave, similar to a diffusional process.
– Artificial dissipation may be intentionally added to improve the numerical stability of a solution.
Mathematics
– In the mathematical study of measure-preserving dynamical systems, dissipation is defined as the wandering set.
– Dissipation involves the conversion of coherent or directed energy flow into a more isotropic distribution of energy.
Dissipation in Waves and Oscillations
– Waves or oscillations can dissipate energy over time, typically due to friction or turbulence. Source: https://en.wikipedia.org/wiki/Dissipation
In thermodynamics, dissipation is the result of an irreversible process that affects a thermodynamic system. In a dissipative process, energy (internal, bulk flow kinetic, or system potential) transforms from an initial form to a final form, where the capacity of the final form to do thermodynamic work is less than that of the initial form. For example, transfer of energy as heat is dissipative because it is a transfer of energy other than by thermodynamic work or by transfer of matter, and spreads previously concentrated energy. Following the second law of thermodynamics, in conduction and radiation from one body to another, the entropy varies with temperature (reduces the capacity of the combination of the two bodies to do work), but never decreases in an isolated system.
In mechanical engineering, dissipation is the irreversible conversion of mechanical energy into thermal energy with an associated increase in entropy.
Processes with defined local temperature produce entropy at a certain rate. The entropy production rate times local temperature gives the dissipated power. Important examples of irreversible processes are: heat flow through a thermal resistance, fluid flow through a flow resistance, diffusion (mixing), chemical reactions, and electric current flow through an electrical resistance (Joule heating).
