Analysis and modelling of turbulent flow in an axially rotating pipe

The analysis and modelling of the structure of turbulent flow in a circular pipe subjected to an axial rotation is presented. Particular attention is paid to determining the terms in various turbulence closures that generate the two main physical features that characterize this flow: a rotationally dependent axial mean velocity and a rotationally dependent mean azimuthal o r swirl velocity relative to the rotating pipe. It is shown that the first feature is well represented by two-dimensional explicit algebraic stress mo dels but is irreproducible by traditional two-equation models. On the other hand, three-dimensional frame-dependent models are needed to predict the p resence of a mean swirl velocity. The latter is argued to be a secondary ef fect which arises from a cubic nonlinearity in standard algebraic models wi th conventional near-wall treatments. Second-order closures are shown to gi ve a more complete description of this flow and can describe both of these features fairly well. In this regard, quadratic pressure-strain models perf orm the best overall when extensive comparisons are made with the results o f physical and numerical experiments. The physical significance of this pro blem and the implications for future research in turbulence are discussed i n detail.