Irreversibility Field in Turbulent Heat Convection Problems

Abstract

Most flows occurring in the field of power generation or refrigeration systems are turbulent. The analysis of the turbulent flows irreversibilities represents the first step in the optimization procedures based on the second law of thermodynamics. The simplicity of the irreversibility bulk level analysis cannot offer all the information about turbulence mechanisms of entropy production. The continuum level, which was recently adapted for the turbulent parabolic flows, is by far most sophisticated. Often it is performed only with the aid of numerical simulation, but it can reveal all the peculiarities of entropy generation structure. Taking into account the importance of entropy creation mechanisms in understanding the second law optimization procedures, this work deal with the theoretical and numerical investigation of irreversibility field for some turbulent heat convection problems. The results show that the irreversibilities created by the turbulent fluctuations are at least as important as those generated by the mean velocity and mean temperature gradients and cannot be neglected.