Aims

The aims of the course are to:

• introduce the physical basis of turbulence as well as its practical implications for engineers; turbulence is a common feature of fluid flows in the atmosphere and the ocean, in aerodynamics and in chemically-reacting flows such as combustion.
• introduce the basic rules of vortex dynamics, which is identified as controlling energy transfers between different scales in a turbulent flow.

Objectives

As specific objectives, by the end of the course students should be able to:

• be aware of the turbulent nature of most flows of interest to engineers and its influence on the transfer processes involving momentum, heat and mass.
• interpret fluid motion in terms of the creation and transport of vorticity.
• understand energy transfer between mean flow and turbulent fluctuations (Reynolds stresses).
• understand energy transfer between the different scales of turbulence and the mechanism of dissipation.
• be aware of the more common phenomenological models of turbulence currently used by engineers and of their underlying assumptions and limitations.

Content

Turbulence and Vortex Dynamics (16L)

• Introduction to turbulence: Pictures of turbulence. Universality of turbulence in flows as the final result of instabilities. Engineering consequences.
• Some simple illustrations of vortex dynamics: The persistence of rotation (angular momentum) in flows. Another description of fluid dynamics: the vorticity equation. Lift and induced motion, with application to aerodynamics and hovering insects. Swirling flows with application to tornadoes, hurricanes and tidal vortices.
• Basic concepts in turbulence theory: Order from chaos - Reynolds decomposition and Reynolds equation. Kinetic energy - Production and Dissipation. Introduction to the different scales in Turbulence, from the integral scale to Kolmogorov's micro-scale. Wall-bounded shear flows. Vortex dynamics at work at the large and small scales (worms).
• Phenomenological models of turbulence: Prandlt's Mixing length and k - e model: their assumptions and limitations. Other models. What can be expected from these turbulence models in terms of velocity and heat transfer.
• Current trends in industrial fluid mechanics.

This syllabus contributes to the following areas of the UK-SPEC standard:

Toggle display of UK-SPEC areas.

 
Last modified: 23/05/2019 15:52