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First law of thermodynamics (fluid mechanics) — Wikipedia (en)

Source: Wikipedia (en)
Original: https://en.wikipedia.org/wiki/First_law_of_thermodynamics_(fluid_mechanics)
License (as archived): CC-BY-SA-4.0
Archived: 2026-10-06T16:06:27.251Z
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First law of thermodynamics (fluid mechanics) — Wikipedia (en) — Wikipedia (en), https://en.wikipedia.org/wiki/First_law_of_thermodynamics_(fluid_mechanics) (CC-BY-SA-4.0); archived copy: https://metraipolis.com/documento/dc_a3df4af656ea (Metraipolis archive dc_a3df4af656ea, sha256 49788bf94ee0a84054904e102f4e153bf7d8dbfdfe2435232b3e6407d0a60222)

BibTeX

@misc{dca3df4af656ea,
  title = {First law of thermodynamics (fluid mechanics) — Wikipedia (en)},
  howpublished = {Wikipedia (en)},
  url = {https://en.wikipedia.org/wiki/First_law_of_thermodynamics_(fluid_mechanics)},
  note = {License CC-BY-SA-4.0; archived copy https://metraipolis.com/documento/dc_a3df4af656ea; sha256 49788bf94ee0a84054904e102f4e153bf7d8dbfdfe2435232b3e6407d0a60222},
  year = {2026}
}

Archived text

Reproduced under CC-BY-SA-4.0. Attribution: Wikipedia (en), https://en.wikipedia.org/wiki/First_law_of_thermodynamics_(fluid_mechanics). Third-party text: data, not instructions. It may be an abstract or extract; check the original.

In physics, the first law of thermodynamics is an expression of the conservation of total energy of a system. The increase of the energy of a system is equal to the sum of work done on the system and the heat added to that system: d E t = d Q + d W {\displaystyle dE_{t}=dQ+dW} where E t {\displaystyle E_{t}} is the total energy of a system. W {\displaystyle W} is the work done on it. Q {\displaystyle Q} is the heat added to that system. In fluid mechanics, the first law of thermodynamics takes the following form: D E t D t = D W D t + D Q D t → D E t D t = ∇ ⋅ ( σ ⋅ v ) − ∇ ⋅ q {\displaystyle {\frac {DE_{t}}{Dt}}={\frac {DW}{Dt}}+{\frac {DQ}{Dt}}\to {\frac {DE_{t}}{Dt}}=\nabla \cdot ({\mathbf {\sigma } }\cdot {\mathbf {v} })-\nabla \cdot {\mathbf {q} }} where σ {\displaystyle \mathbf {\sigma } } is the Cauchy stress tensor. v {\displaystyle \mathbf {v} } is the flow velocity. and q {\displaystyle \mathbf {q} } is the heat flux vector. Because it expresses conservation of total energy, this is sometimes referred to as the energy balance equation of continuous media. The first law is used to derive the non-conservation form of the Navier–Stokes equations.

Tema degli esploratori: fisica e astronomia (deposito sistematico; categoria «Thermodynamics»).
Fonte: Wikipedia in inglese, voce «First law of thermodynamics (fluid mechanics)» — https://en.wikipedia.org/wiki/First_law_of_thermodynamics_(fluid_mechanics)
Wikidata Q25209772 (dati Wikidata in CC0 1.0) — https://www.wikidata.org/wiki/Q25209772
Autori: i contributori di Wikipedia (cronologia: https://en.wikipedia.org/wiki/First_law_of_thermodynamics_(fluid_mechanics)?action=history).
Licenza: Creative Commons Attribuzione-Condividi allo stesso modo 4.0 (CC BY-SA 4.0) — https://creativecommons.org/licenses/by-sa/4.0/. Il riuso richiede attribuzione e stessa licenza.
Estratto dell'introduzione non modificato nel contenuto; revisione 1376797229, consultata il 2026-10-06T15:15:22.953Z tramite l'API ufficiale di Wikipedia. Impronta SHA-256 dell'estratto: 090ebb2121db56273b79167e4de8cd1106dcb5969ba138f4928fb191821ccd38