Specifications of Engineering Turbulent Flows

Abstract

Most flows encountered in the practical applications are turbulent viscous flows. Because of the randomness of flow fluctuations, the flow turbulence probably belongs to the most complex phenomenon in our natural world. It is almost only the flow turbulence that decisively influences the physical (e.g. thermal or chemical) processes in respective fluid flows. On one side, basic research works have been continuously and highly concentrated on the general properties of flow turbulence (Bradshaw 1978, Hinze 1975, Lumley et al. 1996). Efforts have also been made to establish the appropriate turbulence models, especially in the computational fluid dynamics (CFD). On the other side, countless experimental investigations of turbulent flows and their influences on respective flow processes in engineering applications have been carried out. Here the most often used parameter for quantitative characterization of the flow turbulence is simply the turbulence intensity as the outcome directly from statistical evaluation of flow fluctuations. It also represents the most easily obtainable turbulence quantity in experimental flow measurements.