Heat transfer from a partially buried circular cylinder in oscillatory flow

Abstract

With the growing abundance of man-made cylindrical structures located on or close to the seabed, it is important to be able to assess their potential environmental impact. Herein, a model is presented of the viscous-thermal boundary layer in the vicinity of a circular cylinder resting on, or partially buried in, an otherwise flat seabed. To model the influence of wave-induced motions near such a cylinder, we assume oscillatory flow in which the water particle displacements are small with respect to the cylinder radius. A perturbation expansion is utilised to derive solutions of the boundary layer equations, leading to analytical solutions at multiple orders. The unsteady temperature field for various burial depths is then determined numerically using a Crank–Nicolson scheme, and quantitative results, such as the Nusselt number at the cylinder surface, are deduced. Both diffusion and steady convection are responsible for the unsteady transport of temperature. The dynamics of the convective field enhance overall heat transfer from the cylinder and lead to the temperature being transported radially outward near to the seabed.