Tilting While Lifting a Large Object from a Rigid Porous Seabed

Abstract

This study investigates the flow field and the hydrodynamic forces induced by the tilting lift of a large object from a rigid porous seabed using an analytical approach. The flow in the corners between the object and the seabed is a corner flow with a low Reynolds number, and the porous media flow in the seabed obeys the Brinkman equations. The complete boundary conditions for viscous flow, including the continuity of velocities and stresses, are utilized at the seabed-water interface. The Helmholtz decomposition theorem, which decomposes the flow field into irrotational and rotational parts, and a perturbation expansion, are employed to solve the boundary-value problem. Perturbation solutions with first-order corrections are presented, indicating that the flow inside the wedged corner is a Stokes flow driven by the liftup of the object, and the flow within the permeable seabed is a boundary-layer flow. Furthermore, in the wedged corner, the flow induced by the slip velocity at the porous interface is similar to the flow in the paint-scraper problem of Taylor.