With the intensification and industrialization of aquaculture, there is an urgent need for new high-performance aeration devices and energy-saving aeration technology to achieve oxygen saturation. Based on the oxygen transfer equation between air and water two-phase and the Venturi principle, a new tube aeration device was designed, developed, and tested in an attempt to solve these problems. The structural parameters affecting the aeration performance were identified and examined, and optimization experiments were undertaken to enhance the design of this aeration and oxygenation energy-saving technology. The key structural parameters were determined to be the air-water mixing distance, the height of the air hole under the water surface, the ratio of the entrance diameter to the throat diameter, the spiral mixing structure, and the air inlet size. These parameters, together with the airflow rate, influenced the aeration efficiency. Within certain limits, the larger the ratio of the entrance to the throat, the larger the air inlet size was, the more adequate the airflow rate was, and the greater the height of the air hole under the water surface was, the greater the oxygenation efficiency was. However, the additional length and the addition of a spiral mixing structure increased the head loss, reduced the airflow rate, and reduced the aeration and oxygenation efficiency.

A circular particle settling in a confined vertical channel with static fluid is investigated by lattice Boltzmann method, the effect of density ratio on the particle motion and flow pattern is discussed. It shows that the particle starting from an initial position off-center displays various moving modes accompanied by different flow patterns for 1.003 ≤ γ ≤ 5.0: when γ < 1.1, the particle is finally in a stable equilibrium near the centerline and settles uniformly with a symmetrical flow, but there are different modes before reaching the centerline at different density ratios, a monotonic approach appears at γ ≤ 1.005 and an transient overshoot appears at 1.005 < γ < 1.1; When γ = 1.1, a weak oscillation appears in the particle moving but the flow is almost symmetrical, it is in a critical state of the particle moving from stable equilibrium with a transient overshoot to oscillation; When 1.1 < γ ≤ 3.0, the particle oscillates regularly around the centerline with the uniform amplitude and frequency, and it turns into irregularity for γ > 3.0. Meanwhile the rotation of the particle depends on the distance from a wall; it rolls up the closer wall and stops at centerline.