In this study, numerical computation is used to investigate the hydrodynamic characteristics of a torpedo-shaped underwater glider. The physical model of a torpedo-shaped underwater glider is developed by Myring profile equations and analyzed by the computational fluid dynamics approach. The Navier–Stokes equations and the energy equation coupled with the appropriate boundary conditions are solved numerically by using Comsol Multiphysics software. The numerical results contribute to the major part of reducing the effects of fluid flow on the glider’s profile and make the underwater glider more hydrodynamically efficient. The drag and lift forces acting on the underwater glider are enhanced by a higher velocity and a larger angle of attack of the underwater glider. Since the obtained results show a good observation with the experimental works, the need and the practicality of using CFD in the glider design process are proven.

The main objective of this paper is to numerically investigate the transient forward and backward thermocapillary motion of a water droplet in a microchannel occupied by the hexadecane oil. The top and bottom walls of the microchannel are kept at the ambient temperature. Two heat sources activated periodically are put on the front side and rear one of the droplet in a microchannel, respectively. When the heat source is activated, two vortices are formed inside a water droplet and the oil flow passes over the droplet in the microchannel. The forward and backward thermocapillary migration caused by two periodic heat sources results in the thermocapillary stress gradient along the fee interface which drives a water droplet to move to the cold side of the open channel. The mechanism of a droplet migration behavior is consistent with the previous experimental observation. The water droplet first accelerates rapidly, and then decelerates significantly at various intervals. The dynamic contact angle is significantly altered owing to the pressure change exerting on the hexadecane/water interface during the actuation process. The velocity of a water droplet is enlarged by a higher heating power and a larger microchannel height.

Airborne infection isolation (AII) rooms are used to accommodate patients with highly infectious diseases and keep the released pathogens to limit the risk of cross-infection. This paper proposes a concept for an AII room made from two shipping containers to handle the scarcity of hospital beds when the COVID-19 disease spreads over the world. The proposed system consists of the main isolation room, anteroom, and toilet as well as other functional areas. In addition, the main isolation room was modeled with important components such as a supply air vent, exhaust air, a patient, and a bed. The computational fluid dynamics (CFD) approach based on the finite volume method (FVM) is used to solve the three-dimensional governing equations. The CO₂ concentration was used to determine the infectious contaminant concentration of the air in the room. Therefore, the infectious control could be evaluated by the air change per hour (ACH). The numerical results show that the room temperature is maintained at 24°C, which is appropriate for people in the room. The laminar airflow extends downward to the floor after leaving the supply air vent on the ceiling, creating circulating patterns throughout the room. When evaluating the effectiveness of ventilation systems to remove airborne contaminants based on different ACH numbers, the CO₂ concentration in the room was reduced to 581ppm, 477ppm, and 438ppm in the cases of 12 ACH, 24 ACH, and 48 ACH, respectively. As a result, the greater the number of air change per hour, the greater the performance for contaminant removal. It served as the foundation for assessing and optimizing the ventilation system of the portable negative pressure room.