The present research focuses on the development and computer implementation
of a novel threedimensional, anisotropic turbulence model not only capable of
handling complex geometries but also the turbulence driven secondary currents.
The model equations comprise advanced algebraic Reynolds stress models in conjunction
with Reynolds Averaged Navier-Stokes equations. In order to tackle the
complex geometry of compound meandering channels, the body-fitted orthogonal
coordinate system is used. The finite volume method with collocated arrangement
of variables is used for discretization of the governing equations. Pressurevelocity
coupling is achieved by the standard iterative SIMPLE algorithm. A
central differencing scheme and upwind differencing scheme are implemented for
approximation of diffusive and convective fluxes on the control volume faces respectively.
A set of algebraic equations, derived after discretization, are solved
with help of Stones implicit matrix solver.
The model is validated against standard benchmarks on simple and compound
straight channels. For the case of compound meandering channels with varying
sinuosity and floodplain height, the model results are compared with the published
experimental data. It is found that the present method is able to predict
the mean velocity distribution, pressure and secondary flow circulations with reasonably
good accuracy. In terms of engineering applications, the model is also
tested to understand the importance of turbulence driven secondary currents in
slightly curved channel. The development of this unique model has opened many
avenues of future research such as flood risk management, the effects of trees near
the bank on the flow mechanisms and prediction of pollutant transport.
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.