The dual nature of the dead-water phenomenology: Nansen versus Ekman wave-making drags.

ABSTRACT: A ship encounters a higher drag in a stratified fluid compared to a homogeneous one. Grouped under the same "dead-water" vocabulary, two wave-making resistance phenomena have been historically reported. The first, the Nansen wave-making drag, generates a stationary internal wake which produces a kinematic drag with a noticeable hysteresis. The second, the Ekman wave-making drag, is characterized by velocity oscillations caused by a dynamical resistance whose origin is still unclear. The latter has been justified previously by a periodic emission of nonlinear internal waves. Here we show that these speed variations are due to the generation of an internal dispersive undulating depression produced during the initial acceleration of the ship within a linear regime. The dispersive undulating d

SUBMITTER: Fourdrinoy J 

PROVIDER: S-EPMC7382212 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature