Numerical simulation on character of the cavity wake region

In order to investigate the drag character of the aft section of underwater bodies at the different cavity shapes, numerical investigation was conducted using the commercial CFD software Fluent6.0. The investigation shows with the increasing of ventilation flow rate coefficient and development of cavity, the drag coefficient of the aft section decreases, and then increases when it drops to the minimum. Pressure drag is larger than viscous drag of the aft section, and both decrease when ventilation flow rate coefficient increases. The pressure drag starts to increase when it reaches the minimum, which makes the overall vehicle drag also increases when it reaches the minimum. The wetted length of the aft section decreases with the increasing of ventilation flow rate coefficient, and the drag coefficient of aft section increases when the wetted length increases.