This work presents a numerical investigation of turbulent flow over a simplified vehicle model called the Square Back Ahmed Body (SBAB). The simulations are performed at Reynolds number 1 × 10⁵ using the k − $\omega$ SSTSAS turbulence model. The numerical results for the standard reference model, that is, SBAB, have been validated against available experimental data and numerical simulations. The performance of a passive flow controller with four variants on the mean wake topology and the resultant drag reduction is evaluated. The four variants are; (i) straight cavity, (ii) straight cavity with rounded edges, (iii) C-shaped cavity, and (iv) tapered cavity. For a straight cavity with a depth equal to 33.33% of the body height, drag is lowered by 5.63%. With the same cavity depth, rounding the straight cavity edges reduces the drag by 10.67% owing to the streamlining and shortening of the recirculation region. For a C-shaped cavity, the amount of drag reduction increased slightly by 1% more than that off straight cavity with rounded edges, due to improvement in the base pressure distribution compared to that of the latter case. Tapering the cavity edges at an angle of 6° gave a significant drag reduction of 22.55% primarily due to a tremendous decrease in wake size. The drag reduction achieved in all the cases results from the modification in the mean wake topology induced by afterbody shape remodeling. The power spectra of the evolution of the lift coefficient over time reveal a noticeable decrement in the flow randomness with the inclusion of a cavity and its modifications, which interprets the mitigation of the chaotic nature in the wake. The cavity presence has also increased the vorticity spreading rate in the mixing layer and produced significant attenuation of Turbulent Kinetic Energy (TKE).

这项工作提出了一种在称为方背艾哈迈德车身（SBAB）的简化车辆模型上对湍流的数值研究。模拟是在雷诺数为1×10执行⁵使用ķ  - $\omega$SSTSAS湍流模型。标准参考模型（即SBAB）的数值结果已根据可用的实验数据和数值模拟进行了验证。评估了在平均尾流拓扑上具有四个变体的被动式流量控制器的性能以及由此产生的阻力减小。四个变体是；（i）直型腔，（ii）带有圆形边缘的直型腔，（iii）C形腔，以及（iv）锥形腔。对于深度等于人体高度的33.33％的直型空腔，阻力将降低5.63％。在相同的模腔深度下，由于流线化和缩短了回流区域，使直腔边缘变圆可将阻力降低10.67％。对于C形型腔，减阻量比带有圆形边缘的直型腔的减阻量略微增加了1％，与后一种情况相比，由于基本压力分布有所改善。以6°的角度使腔体边缘逐渐变细，可显着降低阻力22.55％，这主要是因为尾流尺寸大大减小了。在所有情况下都实现了减阻，这是由于后车身形状重塑引起的平均尾流拓扑结构的改变。升力系数随时间变化的功率谱显示，随着腔体及其变型的出现，流动随机性显着下降，这解释了尾流中混沌性质的缓解。空腔的存在还增加了混合层中涡度的扩散速率，并显着降低了湍动能（TKE）。以6°的角度使腔体边缘逐渐变细，可显着降低阻力22.55％，这主要是因为尾流尺寸大大减小了。在所有情况下都实现了减阻，这是由于后车身形状重塑引起的平均尾流拓扑结构的改变。升力系数随时间变化的功率谱显示，随着腔体及其变型的出现，流动随机性显着下降，这解释了尾流中混沌性质的缓解。空腔的存在还增加了混合层中涡度的扩散速率，并显着降低了湍动能（TKE）。以6°的角度使腔体边缘逐渐变细，可显着降低阻力22.55％，这主要是因为尾流尺寸大大减小了。在所有情况下都实现了减阻，这是由于后车身形状重塑引起的平均尾流拓扑结构的改变。升力系数随时间变化的功率谱显示，随着腔体及其变型的出现，流动随机性显着下降，这解释了尾流中混沌性质的缓解。空腔的存在还增加了混合层中涡度的扩散速率，并显着降低了湍动能（TKE）。在所有情况下都实现了减阻，这是由于后车身形状重塑引起的平均尾流拓扑结构的改变。升力系数随时间变化的功率谱显示，随着腔体及其变型的出现，流动随机性显着下降，这解释了尾流中混沌性质的缓解。空腔的存在还增加了混合层中涡度的扩散速率，并显着降低了湍动能（TKE）。在所有情况下都实现了减阻，这是由于后车身形状重塑引起的平均尾流拓扑结构的改变。升力系数随时间变化的功率谱显示，随着腔体及其变型的出现，流动随机性显着下降，这解释了尾流中混沌性质的缓解。空腔的存在还增加了混合层中涡度的扩散速率，并显着降低了湍动能（TKE）。解释了缓解混乱本质的方法。空腔的存在还增加了混合层中涡度的扩散速率，并显着降低了湍动能（TKE）。解释了缓解混乱本质的方法。空腔的存在还增加了混合层中涡度的扩散速率，并显着降低了湍动能（TKE）。