Kevin Bobiles

Flow Dynamics over Estuarine Bedforms

In many tide-dominated environments, sandy sediments are being mobilized to develop undulations and rhythmic wavy features, collectively known as bedforms. An in-depth study of their morphology that includes, but is not limited to, their presence, size and movement is important in predicting an accurate hydro-morphodynamic response of the surrounding environment at various spatiotemporal scales. This is in turn an important aspect to many practical and engineering applications such as coastal zone managements, port and channel maintenance. 

Previous studies have characterised flow over triangular bedforms with an angle-of-repose (30°) lee side. However, the shape and dynamics of estuarine bedforms differs significantly to that of angle-of-repose dunes, as they are mainly low- to intermediate-angle dunes (slopes of 5 to 20°) with a sharp pointed crest. Flow properties for this particular bedform morphology and the reversing tidal flow present in an estuarine environment have not been investigated in detail.

Therefore, the main objective of my PhD project is to study and in detail the flow dynamics (flow velocities, turbulent structures, etc.) over estuarine bedforms through a combination of physical experiments and numerical modelling. A series of large-scale flume experiments will be conducted at  BAW Hamburg to study 2D estuarine bedform fields whose modeled shapes are based on measurements obtained in the Weser Estuary. Finally, numerical modeling of flow dynamics over 3D natural bedform fields will complement the flume experiments. Together, the results of both laboratory and numerical studies will allow us to characterise in detail the flow structures over estuarine bedforms and enable better parameterisation of small scale processes into large scale hydro-morphodynamic models.

The project is financed by the German Research Foundation (DFG) - Project number 504378711