Local scour due to submerged horizontal jets

In this thesis, three major studies were done on local scour due to horizontal jets. They are : (i) a detailed literature survey on local scour due to horizontal jets, (ii) investigation on mean and turbulent characteristics of local scour due to horizontal jet and (iii) k-s turbulence modelling of submerged horizontal jet. In this thesis, no experimental studies were performed. A wide range of numerical and experimental studies in the literature have been inspected and it was decided to deal with the studies on "frozen scoured beds". This makes it possible to take one scour profile and find the mean characteristics in it for various conditions of flow such as sluice opening, tailwater depth, upstream submerged jet Froude number, and the quantity of flow. k-s turbulence modelling of submerged horizontal jet using boundary fitted coordinates is developed to predict the mean and turbulent characteristics within the flow. Two dimensional continuity, momentum and transport equations for turbulence quantities are solved numerically by the finite volume method in boundary fitted coordinates. The SIMPLE algorithm is adapted for the computation. The non- rectangular domain of submerged horizontal jet with scoured bed is transformed to mrectangular computational plane. The transformed equations are then solved initially with a guess that the free surface is flat. After each iteration, the new surface profile is then transformed and mesh is generated again. The numerical results of this study were presented and compared with the experimental and numerical results of other researchers. It was especially noticed that the distributions of turbulent intensities, Reynolds stresses and bed shear stresses have had peak values in maximum scour depth region. Also reverse flow was observed in maximum scour depth region. The highest deviation of pressure from hydrostatic was also observed in this region. Basicly, strict agreements were obtained between both the experimental and numerical studies of other researchers and the numerical results of this present study. Keywords: Local scour, submerged horizontal jet, k-s turbulence modelling, finite volume method, boundary-fitted coordinate system.