The article “Nonlinear energy transfer between fluid sloshing and vessel motion” has been accepted for publication in the Journal of Fluid Mechanics.  The article examines the dynamic coupling between a sloshing fluid and the motion of the vessel containing the fluid.  A nonlinear mechanism is identified which leads to an energy exchange between the vessel dynamics and fluid motion which is based on a 1:1 resonance in the linearized equations.  The theory is developed for Cooker’s pendulous sloshing experiment where a rectangular vessel is partially filled with fluid, and is suspended by two cables.  A nonlinear normal form is derived close to an internal 1:1 resonance, with the energy transfer manifested by a heteroclinic connection which connects the purely symmetric sloshing modes (with the vessel stationary) to the purely anti-symmetric sloshing modes (which is coupled to vessel motion).  In practice, this energy transfer can lead to sloshing-induced destabilization of fluid-carrying vessels. An electronic copy of the final-form preprint can be downloaded here.