Electromagnetic flow control in seawater allows to modify the flow by means of a Lorentz-Laplace field of force. This body force is produced by electromagnetic actuators, constituted by wall-flushed permanent magnets and electrodes, which can be associated in network and periodically excited, both in time and space. Within the framework of this study, we have conducted an experimental and numerical investigation on the effect of the electromagnetic forcing on a flow initially at rest and on a flow in a water tunnel. Both types of the studied electromagnetic actuators, normal and parallel, showed that the flow is strongly modified by the forcing, and even that it results completely from it. The obtained results allowed to characterize these modifications and demonstrate, specially for flows initially at rest, the strong sensitivity of the flow to the actuators geometry. A set of objective criteria based on integral quantities has been proposed, which allows to fix objectively the scales of the electromagnetic forcing in terms of length, time, acceleration and velocity, but also those of the flow, as for instance the actuation zone and the local propulsive balances. The experimental results, obtained by means of flow visualization techniques and particle image velocimetry measurements, allowed to validate the analytical models used for the calculation of the field of force. This validation is based on the excellent agreement obtained between numerical simulations and experiments, for the cases of flow initially at rest.
