Research Projects

The vast majority of environmental fluid flows are classified as hydraulically rough. In essence this means that the influence of the bed roughness and local non-uniformity in the near-bed flow on the global flow characteristics cannot be ignored. Yet, traditionally, our understanding of turbulent flows has been almost exclusively based around the time-averaged Navier-stokes equations. Unfortunately, these equations can reveal no information regarding the inherent spatial heterogeneity present in flow over rough boundaries. spatial-averaging of the Navier-stokes equations is therefore the crucial step which must be taken in order to appreciate and reveal the underlying fluid mechanics which govern rough bed hydrodynamics. For instance, the spatially-averaged form of the Navier-stokes equations contains new stress terms which account for the role of roughness form effects in the near-bed momentum transfer. These new terms may be very significant contributors to the overall stress balance and cannot properly be ignored. In this project the investigators intend to parameterize and build predictive models for the new stress terms that are obtained by spatial averaging of the time averaged Navier stokes equations for different kinds of roughness based on experiments in a laboratory flume using Acoustic Doppler Velocimetry.