Oscillatory flow past cylinders at low KC numbers

[Truncated abstract] Offshore pipelines are an indispensable element of the oil and gas industry. Understanding the interactions between the pipelines and their surrounding fluids is of paramount importance to the whole industry.

This thesis is concerned with oscillatory flow over cylindrical structures (representing pipelines) at low governing parameters. The two flow regimes considered are the Honji instability regime and the vortex shedding regime. Honji instability is the hydrodynamic instability responsible for causing a two-dimensional laminar flow to transit into a threedimensional flow. Modifications in the resultant flow field under the Honji instability and the vortex shedding regimes have great engineering relevance as the flow characteristics often closely relate to the hydrodynamic forces on the immersed pipeline structures. However, our current knowledge of the resultant flow behaviours regarding the Honji instability and the vortex shedding phenomena remains quite limited. It is thus
the aim of the present thesis to shed more light on our understanding of the two flow regimes under certain circumstances that are closely related to real engineering problems.