Exploration of measurement principle of a three-dimensional current sensor for measuring the upwelling

The micro upwelling and the large difference of current velocity in the three-dimensions has limited the traditional flow velocity sensors to measure the upwelling. Thus, a three-dimensional current sensor which can measure the horizontal velocity and small upwelling is introduced. Based on the theory of flow around the ball, the horizontal flow velocity is measured by the ball. Additionally, based on Kutta-Joukowski theorem, the vertical flow velocity is measured by the thin disc through the results of horizontal flow velocity measurement. Through theoretical calculation and fluid simulation, the whole structure of this three-dimensional sensor has little effect on the flow around the ball and disc. Based on the results of fluid and structural simulation, it can be known that the device can measure the velocity in the range of 0 mm/s∼400 mm/s and the minimum flow velocity which can be accurately measured is about 8 mm/s; if the horizontal flow velocity is 100 mm/s, the minimum upwelling velocity which can be measured is about 0.0087 mm/s and if the horizontal flow velocity is 30 mm/s, the minimum upwelling velocity which can be measured is about 0.029 mm/s.