The first law of thermodynamics in hydrodynamic steady and unsteady flows

Fuente: arXiv
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Autores principales: Giżyński, Konrad, Makuch, Karol, Paczesny, Jan, Żuk, Paweł, Maciołek, Anna, Hołyst, Robert
Formato: Preprint
Publicado: 2024
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author Giżyński, Konrad
Makuch, Karol
Paczesny, Jan
Żuk, Paweł
Maciołek, Anna
Hołyst, Robert
author_facet Giżyński, Konrad
Makuch, Karol
Paczesny, Jan
Żuk, Paweł
Maciołek, Anna
Hołyst, Robert
contents We studied planar compressible flows of ideal gas as models of a non-equilibrium thermodynamic system. We demonstrate that internal energy $U(S^{*},V,N)$ of such systems in stationary and non-stationary states is the function of only three parameters of state, i.e. non-equilibrium entropy $S^{*}$, volume $V$ and number of particles $N$ in the system. Upon transition between different states, the system obeys the first thermodynamic law, i.e. $dU=T^{*}dS^{*}-p^{*}dV+μ^{*}dN$, where $U=3/2 NRT^{*}$ and $p^{*}V=NRT^{*}$. Placing a cylinder inside the channel, we find that U depends on the location of the cylinder $y_{c}$ only via the parameters of state, i.e. $U(S^{*}(y_{c}),V,N(y_{c}))$ at V=const. Moreover, when the flow around the cylinder becomes unstable, and velocity, pressure, and density start to oscillate as a function of time, t, U depends on t only via the parameters of state, i.e. $U(S^{*}(t),V,N(t))$ for V=const. These examples show that such a form of internal energy is robust and does not depend on the particular boundary conditions even in the unsteady flow.
format Preprint
id arxiv_https___arxiv_org_abs_2403_00463
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The first law of thermodynamics in hydrodynamic steady and unsteady flows
Giżyński, Konrad
Makuch, Karol
Paczesny, Jan
Żuk, Paweł
Maciołek, Anna
Hołyst, Robert
Statistical Mechanics
Fluid Dynamics
We studied planar compressible flows of ideal gas as models of a non-equilibrium thermodynamic system. We demonstrate that internal energy $U(S^{*},V,N)$ of such systems in stationary and non-stationary states is the function of only three parameters of state, i.e. non-equilibrium entropy $S^{*}$, volume $V$ and number of particles $N$ in the system. Upon transition between different states, the system obeys the first thermodynamic law, i.e. $dU=T^{*}dS^{*}-p^{*}dV+μ^{*}dN$, where $U=3/2 NRT^{*}$ and $p^{*}V=NRT^{*}$. Placing a cylinder inside the channel, we find that U depends on the location of the cylinder $y_{c}$ only via the parameters of state, i.e. $U(S^{*}(y_{c}),V,N(y_{c}))$ at V=const. Moreover, when the flow around the cylinder becomes unstable, and velocity, pressure, and density start to oscillate as a function of time, t, U depends on t only via the parameters of state, i.e. $U(S^{*}(t),V,N(t))$ for V=const. These examples show that such a form of internal energy is robust and does not depend on the particular boundary conditions even in the unsteady flow.
title The first law of thermodynamics in hydrodynamic steady and unsteady flows
topic Statistical Mechanics
Fluid Dynamics
url https://arxiv.org/abs/2403.00463