In this paper the formation and development of fluid mud layer happening in ·estu~ries and coastal areas are studied in detail through. numerical simulation on the basis of the 2D shallow water equations for tidal flow, the advection-diffusin equation for cohesive sediment transport and the equations for fluid mud transport. | Vietnam Journal of Mechanics, NCNST of Vietnam T. XX, 1998, No 2 (1 - 10) ·NUMERICAL. SIMULATION OF FLUID MUD LAYER IN ESTUARIES AND COASTAL AREAS DANG HUU CHUNG, Institute of Mechanics, 224 Doi Can, Hanoi, Vietnam Tel: 0084-4-8326138 Fax: 0084-4-8333039 Email: dhchnngl@ ABSTRACT, In this paper the formation and development of fluid mud layer happening in ·estu~ries and coastal areas are studied in detail through. numerical simulation on the basis of the 2D shallow water equations for tidal flow, the advection-diffusi~n equation for cohesive sediment transport and the equations for fluid mud transport. Numerical solution of a special case for a part of the Severn estuary is obtained using the finite difference method as an illustration of the applicability of the model in practice. On the basis of the , initial remarks and evaluation are given. 1. Introduction In,estuaries and coastal regions where there is a high concentration of sediment in suspension, a fluid mud layer is often formed during slack water periods by the process of hindered settling. This amount of sediment comes from the sea or from rivers due 'to the process of flowing through many areas in ·a country or around the sides of mountains. Experiments have established the relationship between settling velocity and cohesive sediment concentration (Tsuruya, Murakami and Irie[l]) and it is seen that a peak value of settling velocity occurs at a concentration of approximately 5kgfm 3 . Once the near bed sediment concentration exceeds this value, mud settles towards the bed more quickly than it can dewater and a layer of fluid mud forms. The movement of the fluid mud layer can be described by a restricted form of the shallow water equations. Many complicated physical processes occur at the interface between sediment in suspension and fluid mud and between fluid mud and the rigid bed. These are represented in the model in a parameterised way. Fluid mud can also be formed by waves .
