Abstract: We consider the plane problem of unsteady flow generated on the interface of a two-layer infinite fluid by a smooth start of a horizontal circular cylinder. The problem is reduced to an integro-differential system of equations for the functions defining the normal and tangential velocity components of fluid particles on the interface and the shape of the interface. A small-time asymptotic solution is constructed for the cylinder moving with constant acceleration from the state of rest without intersecting the interface, whether moving below or above it. The disturbances created at the interface by unsteady motion of the cylinder are investigated for various density ratios and directions of motion. The influence of the density difference on the interface flow and the hydrodynamic forces acting on the cylinder is investigated. An analysis of the asymptotic solution, along with a comparison to free surface flow in a single-layer fluid, reveals that in a two-layered fluid with small density difference, the nonlinear effects and gravitational force contribute negligibly during the initial stage of the cylinder motion.

Cite: Kostikov V.K. , Golikov A.E. , Makarenko N.I.
Unsteady flow of a two-layer fluid generated by a moving circular cylinder
Journal of Fluid Mechanics. 2026. V.1040. P.1-10. DOI: 10.1017/jfm.2026.11884 OpenAlex

Dates:

Published online:

Aug 6, 2026

Identifiers:

≡ OpenAlex:

W7197029742

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