Note on the Time-Dependent Virtual Inertia of a Deforming Body “Translating” in an Unbounded Fluid

Abstract

The concept of virtual inertia of a body with a fixed shape translating in an ideal fluid can be used to describe the force needed to accelerate the body as well as the kinetic energy of the fluid. It is elucidated that this is not a useful possibility in general with respect to a body that has a time-dependent shape. However, for a restricted class of time-dependent shapes, which will be described, the accelerated "translation" of the body in a fluid can be treated analogously to the accelerated translation of a body with a fixed shape. Only bodies that do not shed vorticity are considered.