Transition from laminar to turbulent flow inside an oscillating tank

Laser Doppler Velocimetry is used to measure the flow velocity field inside partially filled tanks whose rectangular cross section is laterally excited by a sinusoidal force of a given frequency and amplitude, over a frequency range in which it would be difficult to use accelerometers or other types of transducers. The present analysis is for tanks of constant size in the direction of the force to which it is subjected, while varying tank length. The first two modes of oscillation are considered. For large excitation force values, the results exhibit nonlinear effects due to the viscous behavior of the fluid. In the case of the second natural frequency, it is noted that the coupling between the longitudinal and transversal mode occurs even before the motion becomes turbulent.