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Dissipation
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<p>In <a href="/facts/Thermodynamics/q4hIx3yP">thermodynamics</a>, dissipation is the result of an <a href="/facts/Irreversible_process/k7PH6Muk">irreversible process</a> that affects a <a href="/facts/Thermodynamic_system/VUr0kpWu">thermodynamic system</a>. In a dissipative process, <a href="/facts/Energy/wd8PrQM7">energy</a> (<a href="/facts/Internal_energy/IYdsoxhR">internal</a>, bulk flow <a href="/facts/Kinetic_energy/aJRxUd4p">kinetic</a>, or system <a href="/facts/Potential_energy/I03KLbmn">potential</a>) <a href="/facts/Energy_transformation/8g4seWcj">transforms</a> from an initial form to a final form, where the capacity of the final form to do <a href="/facts/Work_(thermodynamics)/SjChajtw">thermodynamic work</a> is less than that of the initial form. For example, <a href="/facts/Heat_transfer/1IV3WbFL">transfer of energy as heat</a> is dissipative because it is a transfer of energy other than by thermodynamic work or by transfer of matter, and <a href="/facts/Entropy_(energy_dispersal)/KruLM6E6">spreads</a> previously concentrated energy. Following the <a href="/facts/Second_law_of_thermodynamics/m7SJ2eeH">second law of thermodynamics</a>, in conduction and radiation from one body to another, the <a href="/facts/Entropy/s52IXeFz">entropy</a> varies with <a href="/facts/Temperature/QyGe4gmj">temperature</a> (reduces the capacity of the combination of the two bodies to do work), but never decreases in an isolated system. </p><p>In <a href="/facts/Mechanical_engineering/cbId4fye">mechanical engineering</a>, dissipation is the irreversible conversion of <a href="/facts/Mechanical_energy/gI4oMzoY">mechanical energy</a> into <a href="/facts/Thermal_energy/eVaKAC7K">thermal energy</a> with an associated increase in entropy. </p><p>Processes with defined local temperature <a href="/facts/Entropy_production/HxNR6Yza">produce entropy</a> at a certain rate. The entropy production rate times local temperature gives the dissipated <a href="/facts/Power_(physics)/mkaEyRnn">power</a>. Important examples of irreversible processes are: <a href="/facts/Heat_flow/1IV3WbFL">heat flow</a> through a <a href="/facts/Thermal_resistance/N7VLrDAf">thermal resistance</a>, <a href="/facts/Fluid_flow/y7uzSCfg">fluid flow</a> through a flow resistance, diffusion (mixing), <a href="/facts/Chemical_reaction/GpqWlKrz">chemical reactions</a>, and <a href="/facts/Electric_current/Dc1xdnUX">electric current</a> flow through an <a href="/facts/Electrical_resistance_and_conductance/hxSt0UAj">electrical resistance</a> (<a href="/facts/Joule_heating/eANEHVzP">Joule heating</a>). </p> Look up <i>dissipation</i> in Wiktionary, the free dictionary.