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In [[thermodynamics]], '''dissipation''' is the result of an [[irreversible process]] that takes place in homogeneous [[Thermodynamic system|thermodynamic systems]]. A dissipative process is a process in which [[energy]] ([[Internal energy|internal]], bulk flow [[Kinetic energy|kinetic]], or system [[Potential energy|potential]]) is [[Energy transformation|transformed]] from some initial form to some final form; the capacity of the final form to do [[mechanical work]] is less than that of the initial form. For example, [[Heat Transfer|heat transfer]] is dissipative because it is a transfer of internal energy from a hotter body to a colder one. Following the [[second law of thermodynamics]], the [[entropy]] varies with [[temperature]] (reduces the capacity of the combination of the two bodies to do mechanical work), but never decreases in an isolated system.

In [[thermodynamics]], '''dissipation''' is the result of an [[irreversible process]] that takes place in homogeneous [[Thermodynamic system|thermodynamic systems]]. A dissipative process is a process in which [[energy]] ([[Internal energy|internal]], bulk flow [[Kinetic energy|kinetic]], or system [[Potential energy|potential]]) is [[Energy transformation|transformed]] from some initial form to some final form; the capacity of the final form to do [[mechanical work]] is less than that of the initial form. For example, [[Heat Transfer|heat transfer]] is dissipative because it is a transfer of internal energy from a hotter body to a colder one. Following the [[second law of thermodynamics]], the [[entropy]] varies with [[temperature]] (reduces the capacity of the combination of the two bodies to do mechanical work), but never decreases in an isolated system.

In thermodynamics, dissipation is the result of an irreversible process that takes place in homogeneous thermodynamic systems. A dissipative process is a process in which energy (internal, bulk flow kinetic, or system potential) is transformed from some initial form to some final form; the capacity of the final form to do mechanical work is less than that of the initial form. For example, heat transfer is dissipative because it is a transfer of internal energy from a hotter body to a colder one. Following the second law of thermodynamics, the entropy varies with temperature (reduces the capacity of the combination of the two bodies to do mechanical work), but never decreases in an isolated system.

In thermodynamics, dissipation is the result of an irreversible process that takes place in homogeneous thermodynamic systems. A dissipative process is a process in which energy (internal, bulk flow kinetic, or system potential) is transformed from some initial form to some final form; the capacity of the final form to do mechanical work is less than that of the initial form. For example, heat transfer is dissipative because it is a transfer of internal energy from a hotter body to a colder one. Following the second law of thermodynamics, the entropy varies with temperature (reduces the capacity of the combination of the two bodies to do mechanical work), but never decreases in an isolated system.

在热力学中，耗散是在均匀热力学系统中发生的不可逆性的结果。耗散过程是能量(内部、体流动动力学或系统势)从某种初始形式转化为某种最终形式的过程，最终形式做机械功的能力小于初始形式。例如，热传递是耗散的，因为它是内部能量从一个较热的物体向一个较冷的物体的转移。在热力学第二定律之后，熵随温度变化(降低了两个物体组合做机械功的能力) ，但是在一个孤立的系统中熵不会减少。

在热力学中，<font color="#ff8000"> 耗散Dissipation</font>是在均匀热力学系统中发生的不可逆性的结果。耗散过程是能量(内部、整体流动动力学或系统势)从某种初始形式转化为某种最终形式的过程，最终形式做机械功的能力小于初始形式。例如，热传递是耗散的，因为它是内部能量从一个较热的物体向一个较冷的物体的转移。在热力学第二定律之后，熵随温度变化(降低了两个物体组合做机械功的能力) ，但是在一个孤立的系统中熵不会减少。

{{Wiktionary}}

{{Wiktionary}}

== Definition ==

== Definition 定义==

Thermodynamic dissipative processes are essentially irreversible. They [[entropy production|produce entropy]] at a finite rate. In a process in which the temperature is locally continuously defined, the local density of rate of entropy production times local temperature gives the local density of dissipated power.[Definition needed!]

Thermodynamic dissipative processes are essentially irreversible. They [[entropy production|produce entropy]] at a finite rate. In a process in which the temperature is locally continuously defined, the local density of rate of entropy production times local temperature gives the local density of dissipated power.[Definition needed!]

A particular occurrence of a dissipative process cannot be described by a single individual Hamiltonian formalism. A dissipative process requires a collection of admissible individual Hamiltonian descriptions, exactly which one describes the actual particular occurrence of the process of interest being unknown. This includes friction, and all similar forces that result in decoherency of energy&mdash;that is, conversion of coherent or directed energy flow into an indirected or more isotropic distribution of energy.

A particular occurrence of a dissipative process cannot be described by a single individual Hamiltonian formalism. A dissipative process requires a collection of admissible individual Hamiltonian descriptions, exactly which one describes the actual particular occurrence of the process of interest being unknown. This includes friction, and all similar forces that result in decoherency of energy&mdash;that is, conversion of coherent or directed energy flow into an indirected or more isotropic distribution of energy.

耗散过程的特殊现象不能用单个的哈密顿形式来描述。耗散过程需要一系列可接受的个体哈密顿描述，准确地描述未知的兴趣过程的实际特殊发生。这包括摩擦力，以及所有导致能量退相干的类似作用力---- 也就是说，相干或定向能量流转化为间接或更为各向同性的能量分布。

耗散过程的特殊现象不能用单个的哈密顿形式来描述。耗散过程需要一系列可接受的个体哈密顿描述，准确地描述未知的兴趣过程的实际特殊发生。这包括摩擦力，以及所有导致能量退相干的类似作用力---- 也就是说相干或定向能量流转化为间接或更为各向同性的能量分布。

=== Energy ===

=== Energy 能量===

"The conversion of mechanical energy into heat is called energy dissipation." – ''François Roddier''<ref>[http://www.editions-parole.net/?product=thermodynamique-de-levolution-un-essai-de-thermo-bio-sociologie Roddier F., ''Thermodynamique de l'évolution (The Thermodynamics of Evolution)'', parole éditions, 2012]</ref> The term is also applied to the loss of energy due to generation of unwanted heat in electric and electronic circuits.

"The conversion of mechanical energy into heat is called energy dissipation." – ''François Roddier''<ref>[http://www.editions-parole.net/?product=thermodynamique-de-levolution-un-essai-de-thermo-bio-sociologie Roddier F., ''Thermodynamique de l'évolution (The Thermodynamics of Evolution)'', parole éditions, 2012]</ref> The term is also applied to the loss of energy due to generation of unwanted heat in electric and electronic circuits.

"The conversion of mechanical energy into heat is called energy dissipation." – François Roddier The term is also applied to the loss of energy due to generation of unwanted heat in electric and electronic circuits.

"The conversion of mechanical energy into heat is called energy dissipation." – François Roddier The term is also applied to the loss of energy due to generation of unwanted heat in electric and electronic circuits.

=== Computational physics ===

=== Computational physics计算物理学 ===

In [[computational physics]], numerical dissipation (also known as "numerical diffusion") refers to certain side-effects that may occur as a result of a numerical solution to a differential equation. When the pure [[advection]] equation, which is free of dissipation, is solved by a numerical approximation method, the energy of the initial wave may be reduced in a way analogous to a diffusional process. Such a method is said to contain 'dissipation'. In some cases, "artificial dissipation" is intentionally added to improve the [[numerical stability]] characteristics of the solution.<ref>Thomas, J.W. Numerical Partial Differential Equation: Finite Difference Methods. Springer-Verlag. New York. (1995)</ref>

In [[computational physics]], numerical dissipation (also known as "numerical diffusion") refers to certain side-effects that may occur as a result of a numerical solution to a differential equation. When the pure [[advection]] equation, which is free of dissipation, is solved by a numerical approximation method, the energy of the initial wave may be reduced in a way analogous to a diffusional process. Such a method is said to contain 'dissipation'. In some cases, "artificial dissipation" is intentionally added to improve the [[numerical stability]] characteristics of the solution.<ref>Thomas, J.W. Numerical Partial Differential Equation: Finite Difference Methods. Springer-Verlag. New York. (1995)</ref>

In computational physics, numerical dissipation (also known as "numerical diffusion") refers to certain side-effects that may occur as a result of a numerical solution to a differential equation. When the pure advection equation, which is free of dissipation, is solved by a numerical approximation method, the energy of the initial wave may be reduced in a way analogous to a diffusional process. Such a method is said to contain 'dissipation'. In some cases, "artificial dissipation" is intentionally added to improve the numerical stability characteristics of the solution.

In computational physics, numerical dissipation (also known as "numerical diffusion") refers to certain side-effects that may occur as a result of a numerical solution to a differential equation. When the pure advection equation, which is free of dissipation, is solved by a numerical approximation method, the energy of the initial wave may be reduced in a way analogous to a diffusional process. Such a method is said to contain 'dissipation'. In some cases, "artificial dissipation" is intentionally added to improve the numerical stability characteristics of the solution.

=== Mathematics ===

=== Mathematics数学 ===

A formal, mathematical definition of dissipation, as commonly used in the mathematical study of [[measure-preserving dynamical system]]s, is given in the article ''[[wandering set]]''.

A formal, mathematical definition of dissipation, as commonly used in the mathematical study of [[measure-preserving dynamical system]]s, is given in the article ''[[wandering set]]''.

== Examples ==

== Examples例子 ==

=== In hydraulic engineering ===

=== In hydraulic engineering 水利工程  ===

Dissipation is the process of converting mechanical energy of downward-flowing water into thermal and acoustical energy. Various devices are designed in stream beds to reduce the kinetic energy of flowing waters to reduce their [[erosion|erosive potential]] on banks and [[stream bed|river bottoms]]. Very often, these devices look like small [[waterfall]]s or [[waterfall#Types|cascades]], where water flows vertically or over [[riprap]] to lose some of its [[kinetic energy]].

Dissipation is the process of converting mechanical energy of downward-flowing water into thermal and acoustical energy. Various devices are designed in stream beds to reduce the kinetic energy of flowing waters to reduce their [[erosion|erosive potential]] on banks and [[stream bed|river bottoms]]. Very often, these devices look like small [[waterfall]]s or [[waterfall#Types|cascades]], where water flows vertically or over [[riprap]] to lose some of its [[kinetic energy]].

Dissipation is the process of converting mechanical energy of downward-flowing water into thermal and acoustical energy. Various devices are designed in stream beds to reduce the kinetic energy of flowing waters to reduce their erosive potential on banks and river bottoms. Very often, these devices look like small waterfalls or cascades, where water flows vertically or over riprap to lose some of its kinetic energy.

Dissipation is the process of converting mechanical energy of downward-flowing water into thermal and acoustical energy. Various devices are designed in stream beds to reduce the kinetic energy of flowing waters to reduce their erosive potential on banks and river bottoms. Very often, these devices look like small waterfalls or cascades, where water flows vertically or over riprap to lose some of its kinetic energy.

=== Irreversible processes ===

=== Irreversible processes不可逆转过程 ===

Important examples of irreversible processes are:  

Important examples of irreversible processes are:  

=== Waves or oscillations ===

=== Waves or oscillations波或振荡 ===

[[Wave]]s or [[oscillation]]s, lose [[energy]] over [[time]], typically from [[friction]] or [[turbulence]]. In many cases, the "lost" energy raises the [[temperature]] of the system. For example, a [[wave]] that loses [[amplitude]] is said to dissipate. The precise nature of the effects depends on the nature of the wave: an [[atmospheric wave]], for instance, may dissipate close to the surface due to [[friction]] with the land mass, and at higher levels due to [[radiative cooling]].

[[Wave]]s or [[oscillation]]s, lose [[energy]] over [[time]], typically from [[friction]] or [[turbulence]]. In many cases, the "lost" energy raises the [[temperature]] of the system. For example, a [[wave]] that loses [[amplitude]] is said to dissipate. The precise nature of the effects depends on the nature of the wave: an [[atmospheric wave]], for instance, may dissipate close to the surface due to [[friction]] with the land mass, and at higher levels due to [[radiative cooling]].

Waves or oscillations, lose energy over time, typically from friction or turbulence. In many cases, the "lost" energy raises the temperature of the system. For example, a wave that loses amplitude is said to dissipate. The precise nature of the effects depends on the nature of the wave: an atmospheric wave, for instance, may dissipate close to the surface due to friction with the land mass, and at higher levels due to radiative cooling.

Waves or oscillations, lose energy over time, typically from friction or turbulence. In many cases, the "lost" energy raises the temperature of the system. For example, a wave that loses amplitude is said to dissipate. The precise nature of the effects depends on the nature of the wave: an atmospheric wave, for instance, may dissipate close to the surface due to friction with the land mass, and at higher levels due to radiative cooling.

波浪或振荡，随着时间的推移会失去能量，通常是由于摩擦或紊流。在许多情况下，“损失”的能量提高了系统的温度。例如，失去振幅的波叫做消散波。影响的确切性质取决于波的性质: 例如，大气波可能由于与陆地质量的摩擦而接近地表消散，由于辐射冷却的缘故而在更高的水平上消散。

波或振荡，随着时间的推移会失去能量，通常是由于摩擦或紊流。在许多情况下，“损失”的能量提高了系统的温度。例如，失去振幅的波叫做消散波。影响的确切性质取决于波的性质: 例如，大气波可能由于与陆地质量的摩擦而于接近地表处消散，由于辐射冷却的缘故而在更高的水平上消散。

== History ==

== History历史 ==

{{See also |Timeline of thermodynamics}}

{{See also |Timeline of thermodynamics}}

The concept of dissipation was introduced in the field of thermodynamics by William Thomson (Lord Kelvin) in 1852. Lord Kelvin deduced that a subset of the above-mentioned irreversible dissipative processes will occur unless a process is governed by a "perfect thermodynamic engine". The processes that Lord Kelvin identified were friction, diffusion, conduction of heat and the absorption of light.

The concept of dissipation was introduced in the field of thermodynamics by William Thomson (Lord Kelvin) in 1852. Lord Kelvin deduced that a subset of the above-mentioned irreversible dissipative processes will occur unless a process is governed by a "perfect thermodynamic engine". The processes that Lord Kelvin identified were friction, diffusion, conduction of heat and the absorption of light.

耗散的概念是由威廉 · 汤姆森(开尔文勋爵)于1852年在热力学领域提出的。开尔文勋爵推断，上述不可逆耗散过程的一个子集将会发生，除非一个过程被一个“完美的热力学发动机”所支配。开尔文勋爵确定的过程是摩擦、扩散、热传导和光的吸收。

耗散的概念是由威廉·汤姆森(开尔文勋爵)于1852年在热力学领域提出的。开尔文勋爵推断，上述不可逆耗散过程的一个子集将会发生，除非一个过程由一个“完美的热力学发动机”控制。开尔文勋爵确定的过程是摩擦、扩散、热传导和光吸收。

==See also==

==See also参见==

*[[Entropy production]]

*[[Entropy production]]

 

*[[Flood control]]

*[[Flood control]]

 

*[[Principle of maximum entropy]]

*[[Principle of maximum entropy]]

 

*[[Two-dimensional gas]]

*[[Two-dimensional gas]]

 

==References参考==

==References==

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