Deformation and orientation of an elastic slender body sedimenting in a viscous liquid

The sedimentation of a flexible slender particle within an otherwise quiescent viscous fluid is considered. The resulting distributed force along the body is shown to cause the deformation of the slender particle. An analytic solution describing this phenomenon is provided for the case of small deformation amplitudes. The effect of particle elasticity on determining its preferred orientation during sedimentation is also examined. One finds that, as a result of its deformation, the particle experiences a torque which tends to orient it toward a horizontal state, in which the long axis is perpendicular to the direction of settling.