scholarly journals Testing the Steady-State Fluctuation Relation in the Solar Photospheric Convection

Entropy ◽  
2020 ◽  
Vol 22 (7) ◽  
pp. 716
Author(s):  
Giorgio Viavattene ◽  
Giuseppe Consolini ◽  
Luca Giovannelli ◽  
Francesco Berrilli ◽  
Dario Del Moro ◽  
...  
Keyword(s):  
Steady State ◽  
Entropy Production ◽  
Production Rate ◽  
Local Level ◽  
Entropy Production Rate ◽  
Quasi Steady State ◽  
The Sun ◽  
Statistical Features ◽  
Local Entropy ◽  
Fluctuation Relation

The turbulent thermal convection on the Sun is an example of an irreversible non-equilibrium phenomenon in a quasi-steady state characterized by a continuous entropy production rate. Here, the statistical features of a proxy of the local entropy production rate, in solar quiet regions at different timescales, are investigated and compared with the symmetry conjecture of the steady-state fluctuation theorem by Gallavotti and Cohen. Our results show that solar turbulent convection satisfies the symmetries predicted by the fluctuation relation of the Gallavotti and Cohen theorem at a local level.

scholarly journals Evaluating a proxy of the local entropy production rate on the solar photosphere

2019 ◽  
Vol 1226 ◽  
pp. 012004 ◽  
Author(s):  
G Viavattene ◽  
F Berrilli ◽  
G Consolini ◽  
D Del Moro ◽  
F Giannattasio ◽  
...  
Keyword(s):  
Entropy Production ◽  
Production Rate ◽  
Entropy Production Rate ◽  
Solar Photosphere ◽  
Local Entropy

Steady state traffic flow, entropy production rate, temporal fluctuations and fuel consumption

2006 ◽  
Vol 361 (2) ◽  
pp. 630-642 ◽  
Author(s):  
J.A. Montemayor-Aldrete ◽  
P. Ugalde-Vélez ◽  
M. del Castillo-Mussot ◽  
C.A. Vázquez-Villanueva ◽  
G.J. Vázquez ◽  
...  
Keyword(s):  
Steady State ◽  
Entropy Production ◽  
Production Rate ◽  
Fuel Consumption ◽  
Traffic Flow ◽  
Entropy Production Rate ◽  
Temporal Fluctuations

scholarly journals Non-Equilibrium Thermodynamics and Stochastic Dynamics of a Bistable Catalytic Surface Reaction

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 811 ◽  
Author(s):  
Miguel Pineda ◽  
Michail Stamatakis
Keyword(s):  
Steady State ◽  
Entropy Production ◽  
Production Rate ◽  
Surface Reaction ◽  
Stochastic Dynamics ◽  
Reaction System ◽  
Entropy Production Rate ◽  
Minimum Entropy ◽  
Catalytic Surface ◽  
Non Equilibrium

Catalytic surface reaction networks exhibit nonlinear dissipative phenomena, such as bistability. Macroscopic rate law descriptions predict that the reaction system resides on one of the two steady-state branches of the bistable region for an indefinite period of time. However, the smaller the catalytic surface, the greater the influence of coverage fluctuations, given that their amplitude normally scales as the square root of the system size. Thus, one can observe fluctuation-induced transitions between the steady-states. In this work, a model for the bistable catalytic CO oxidation on small surfaces is studied. After a brief introduction of the average stochastic modelling framework and its corresponding deterministic limit, we discuss the non-equilibrium conditions necessary for bistability. The entropy production rate, an important thermodynamic quantity measuring dissipation in a system, is compared across the two approaches. We conclude that, in our catalytic model, the most favorable non-equilibrium steady state is not necessary the state with the maximum or minimum entropy production rate.

scholarly journals A numerically research on energy loss evaluation in a centrifugal pump system based on local entropy production method

2017 ◽  
Vol 21 (3) ◽  
pp. 1287-1299 ◽  
Author(s):  
Hucan Hou ◽  
Yongxue Zhang ◽  
Zhenlin Li
Keyword(s):  
Energy Loss ◽  
Entropy Production ◽  
Production Rate ◽  
Centrifugal Pump ◽  
Production Method ◽  
Assessment System ◽  
Entropy Production Rate ◽  
Local Entropy ◽  
Pump System ◽  
Rate Distribution

Inspired by wide application of the second law of thermodynamics to flow and heat transfer devices, local entropy production analysis method was creatively introduced into energy assessment system of centrifugal water pump. Based on Reynolds stress turbulent model and energy equation model, the steady numerical simulation of the whole flow passage of one IS centrifugal pump was carried out. The local entropy production terms were calculated by user defined functions, mainly including wall entropy production, turbulent entropy production, and viscous entropy production. The numerical results indicated that the irreversible energy loss calculated by the local entropy production method agreed well with that calculated by the traditional method but with some deviations which were probably caused by high rotatability and high curvature of impeller and volute. The wall entropy production and turbulent entropy production took up large part of the whole entropy production about 48.61% and 47.91%, respectively, which indicated that wall friction and turbulent fluctuation were the major factors in affecting irreversible energy loss. Meanwhile, the entropy production rate distribution was discussed and compared with turbulent kinetic energy dissipation rate distribution, it showed that turbulent entropy production rate increased sharply at the near wall regions and both distributed more uniformly. The blade region in leading edge near suction side, trailing edge and volute tongue were the main regions to generate irreversible exergy loss. This research broadens a completely new view in evaluating energy loss and further optimizes pump using entropy production minimization.

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