Characterizing flows with an instrumented particle measuring Lagrangian accelerations

In this paper we present a novel Lagrangian measurement technique: an instrumented particle which continuously transmits the force/acceleration acting on it as it is advected in a flow. We have developed signal processing methods to extract information on the flow from the acceleration signal transmitted by the particle. Notably, we are able to characterize the force acting on the particle and identify the presence of a permanent large-scale vortex structure. Our technique provides a fast, robust and efficient tool to characterize flows and is particularly suited to obtain Lagrangian statistics along long trajectories or in cases where optical measurement techniques are not or hardly applicable. (paper)