Vectrino: a micro-sensor for turbulent flows
The NTAP project focused on studying nutrient dynamics mediated through turbulence and plankton in European coastal waters. This involved extended use of laboratory flasks and culture vessels in biological laboratories. However, commonly available sensors were not suitable for use in these highly constrained environments in terms of size and shape specifications. For this reason, a new sensor for laboratory measurement of small-scale turbulence was needed. Taking into account the restrictions imposed, Vectrino was developed. This sensor had originally been based on an existing device, the Acoustic Doppler Velocimeter (ADV) that is widely used. This involves a high-resolution 3D instrument for measuring velocity fluctuations using focused acoustic beams with high sampling rates. ADV has been greatly modified since sensor elements and related electronics had to be miniaturised. This included the addition of a newly designed probe with minimum mechanical dimensions as dictated by the size of the acoustic ceramic elements. Several performance enhancing elements were also introduced including a fourth receiver element for more accurate measurements at low to moderate turbulence levels. In comparison to ADV, Vectrino has the potential to measure smaller volumes even at lower turbulence levels in a more rapid, cost-effective and precise way. For instance, the output rate for the 3D velocity measurement has been increased from 25Hz to 200Hz allowing its use in a wider spectrum of possible applications. Apart from biological studies, Vectrino may also be used in all fields ranging from basic fluid mechanics to ocean wave motion.
