Turbulent Flows

Turbulent flows are characterized by spatiotemporal fluctuations in velocity, pressure, temperature, and others informations. As a consequence of these fluctuations, the turbulent regime in a flow contributes significantly to the transport of linear momentum, energy and mass. Turbulence is defined as a flow regime in a fluid in which the instantaneous variables exhibit irregular and apparently random fluctuations such that only statistical properties can be quantified and analyzed. The study of transport phenomena is greatly hampered by the presence of these fluctuations. Any simplification in the analysis of the effects of turbulence is very advantageous from a physical, mathematical and computational point of view. The constant search for such simplifications is one of the main objectives in the development of new turbulence models. The author of this book aims to provide a broad exposition on the subject of Turbulent Flows and its modeling, where the theoretical foundations and the main approach techniques used in the modeling of the phenomenon are presented. Particular emphasis is given to the discussion and analysis of the main physical aspects of turbulent flows, as well as the theoretical modeling of this phenomena. The author sought to develop a textbook for teaching postgraduate and/or advanced undergraduate courses. Thus, the following topics were presented in the book: an introduction to the subject; differential modeling for Fluid Mechanics; transition to turbulence; homogeneous and isotropic turbulence; equations for turbulence and the closure problem; URANS methodology and closure models; LES methodology and sub-grid closure models and hybrid URANS-URANS and URANS-LES methodologies.