This course provides an introduction to continuum modelling of environmental and industrial situations and to the physical processes of diffusion and convection. Often flows are driven by differences in density within an inhomogeneous fluid, such as those due to salinity or temperature differences or the presence of suspended sediment. A hierarchy of approaches is presented for the analysis of these buoyancy driven flows, ranging from dimensional analysis which may supplement empirical results, to more complicated models which utilise partial differential equations based upon the principles of mass, momentum and energy conservation. A wide range of applications is introduced, including transport and mixing in rivers, dispersion in ground water flows and the atmosphere, natural ventilation within buildings, flows in porous media and two-phase flows. For each application, due consideration is given to the scope and appropriate level of complexity of the model.
Turbulence is a key feature of many environmental flows.
Simple models are developed, based on global conservation principles, for plumes, jets and gravity currents. In addition, Reynolds averaging is presented for more detailed modelling of the flows. The ideas of this unit are developed further in the Level 4 unit Advanced Fluid Dynamics . The Level 4 Waves and Instabilities unit also contain material relevant to fluid dynamics. Teaching Methods Lectures including some laboratory demonstrations of the flows.