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Thermal Transport and Entropy Production Mechanisms in a Turbulent Round Jet at Supercritical Thermodynamic Conditions

Institute of Energy and Power Plant Technology, Technische Universität Darmstadt, Darmstadt 64287, Germany
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Entropy 2017, 19(8), 404; https://doi.org/10.3390/e19080404
Received: 1 July 2017 / Revised: 29 July 2017 / Accepted: 2 August 2017 / Published: 5 August 2017
(This article belongs to the Section Thermodynamics)
In the present paper, thermal transport and entropy production mechanisms in a turbulent round jet of compressed nitrogen at supercritical thermodynamic conditions are investigated using a direct numerical simulation. First, thermal transport and its contribution to the mixture formation along with the anisotropy of heat fluxes and temperature scales are examined. Secondly, the entropy production rates during thermofluid processes evolving in the supercritical flow are investigated in order to identify the causes of irreversibilities and to display advantageous locations of handling along with the process regimes favorable to mixing. Thereby, it turned out that (1) the jet disintegration process consists of four main stages under supercritical conditions (potential core, separation, pseudo-boiling, turbulent mixing), (2) causes of irreversibilities are primarily due to heat transport and thermodynamic effects rather than turbulence dynamics and (3) heat fluxes and temperature scales appear anisotropic even at the smallest scales, which implies that anisotropic thermal diffusivity models might be appropriate in the context of both Reynolds-averaged Navier–Stokes (RANS) and large eddy simulation (LES) approaches while numerically modeling supercritical fluid flows. View Full-Text
Keywords: direct numerical simulation; turbulent round jet; supercritical fluid flow; entropy generation; irreversibility; turbulent heat transport direct numerical simulation; turbulent round jet; supercritical fluid flow; entropy generation; irreversibility; turbulent heat transport
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MDPI and ACS Style

Ries, F.; Janicka, J.; Sadiki, A. Thermal Transport and Entropy Production Mechanisms in a Turbulent Round Jet at Supercritical Thermodynamic Conditions. Entropy 2017, 19, 404.

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