Calculation of Hydrodynamic Resistance Coefficient of Diver with and without Diving Equipment by CFD Method at Surface and Near Surface Condition

The main purpose of the present study is to examine the effects of diving equipment include oxygen tank, tank valve, hose, mouthpiece and diving fins on increasing the resistance and resistance coefficient of the diver's body at free surface condition. The other purpose is calculation of the resistance and resistance coefficient of a diver with equipment in different positions. This study uses a computational fluid dynamics methodology. SST K-ω turbulent model is implemented in the Star-CCM+ application and is applied to the flow around a three-dimensional bare hull of an adult human during diving with effect of carrying diving equipment. Four different positions are considered: diving horizontally, diving with attack angle of 30 degrees, diving with attack angle of 45 degrees and diving with attack angle of 45 degrees while knees are bent at 45 degrees backward. The results for horizontally diving are compared with the bare hull of adult human without equipment. All the simulations are done in surface and near surface situations with two-phases simulation. The flow velocities between 0.5 and 2m/s with increasing step of 0.5m/s are considered in the simulations which are typical speed of swimmers. The results show that using diving equipment leads to increasing total resistance about 90% to 128% during near surface swimming and about 28% to 62% in surface swimming just in higher velocities. The results of this research can be used for designing all types of marine propulsion vehicles, water scooter, and all swimming thrusters.

本研究的核心目的在于探究各类潜水装备对自由水面条件下潜水员身体所受阻力及阻力系数的提升效应，所涉装备包括氧气瓶（oxygen tank）、气瓶阀（tank valve）、呼吸软管（hose）、咬嘴（mouthpiece）以及潜水脚蹼（diving fins）。另一项研究目标为计算不同姿态下配备全套潜水装备的潜水员所受的阻力与阻力系数。
本研究采用计算流体动力学（computational fluid dynamics）方法，在Star-CCM+软件中搭载SST K-ω湍流模型（SST K-ω turbulent model），用于模拟携带潜水装备的成年人体三维裸模型周围的流场。本次研究设置了四种不同的潜水姿态：水平俯卧潜水、攻角30度潜水、攻角45度潜水，以及双膝向后弯曲45度的攻角45度潜水。
将水平俯卧潜水的模拟结果与无装备的成年人体裸模型进行对比。所有模拟均采用两相流模拟方案，分别在水面及近水面工况下开展。模拟选取的流速区间为0.5~2m/s，步长为0.5m/s，该流速范围符合游泳者的典型运动速度。
研究结果显示：在近水面游泳工况下，使用潜水装备可使总阻力提升约90%至128%；而在水面游泳工况下，仅在较高流速区间内，总阻力提升幅度约为28%至62%。本研究成果可应用于各类船舶推进装置、水上摩托（water scooter）以及所有游泳推进器的设计研发。