Lift force during deceleration of underwater slender body with various length-to-diameter ratios

This study investigates the lift force dynamics on a slender body moving near a free water surface or an ice sheet. Combining experimental and theoretical approaches, the research examines two types of motion: uniform motion at constant velocity and deceleration from a given velocity to rest. The experiments were carried out a 14 m × 3 m × 1 m ice tank, with a freshwater ice cover formed under low air temperature conditions. Theoretically, the problem is solved within the framework of the linear wave theory, using the source-sink method for modeling the flow surface of a slender axisymmetric body. The influence of length-to-diameter ratios L/D = 6 – 14 and the slender body deceleration on the change in lift force depending on time, velocity, and ice plate thickness was investigated. The study also identifies the conditions under which the lift force reverses sign during deceleration, a phenomenon that can lead to a dangerous proximity to the ice surface.