A backward facing step (BFS) flow has been investigated extensively by the research community experimentally and computationally due to its significant flow features because of the presence of the separation-reattachment mechanism. The strength of this mechanism varies based on the Reynolds number (RN). For turbulent flow at low RN, the separation-reattachment mechanism computations may be expensive due to high requirements of fine grid which varies based on the employed turbulence model. Several classes of turbulence models have been attempted for capturing complex fluid flow phenomena, namely zero, one, two, three, four and seven equation models. Selected turbulence models from each class have been employed in this paper in order to predict the reattachment length behind BFS at RN of 37,000. The grid independent solution is obtained using modified general Richardson method based on three relatively coarse grids which significantly reduces the computational cost. It is found that the predicted reattachment length for employed turbulence models agrees well with experiment and is considered as a grid independent solution. The visualization of computational domain on the wind tunnel shows similar trends for flow developed in the region of reattachment length. This work can substantially reduce cost of computations for the prediction of reattachment length in BFS flow problem and shows how closely turbulence models perform when grid independent solution is obtained.

由于存在分离-重新连接机制，其重要的流动特性使研究人员在实验和计算方面对逆向步骤（BFS）流动进行了广泛的研究。该机制的强度根据雷诺数（RN）的不同而不同。对于低RN的湍流，由于对细网格的高要求（基于所采用的湍流模型而变化），分离-重新连接机制的计算可能会很昂贵。已经尝试了几种类型的湍流模型来捕获复杂的流体流动现象，即零，一，二，三，四和七方程模型。为了预测在37,000 RN处BFS后面的重新附着长度，已在每个类别中使用了选定的湍流模型。网格无关的解决方案是使用改进的通用Richardson方法基于三个相对粗糙的网格获得的，这大大降低了计算成本。发现所采用的湍流模型的预测再附接长度与实验吻合得很好，并被视为与网格无关的解决方案。风洞中计算域的可视化显示了在重新连接长度区域中流动的相似趋势。这项工作可以大大降低BFS流动问题中的重新连接长度预测的计算成本，并显示出获得独立于网格的解时湍流模型执行的紧密程度。结果发现，采用的湍流模型的预测再附着长度与实验吻合得很好，被认为是与网格无关的解决方案。风洞中计算域的可视化显示了在重新连接长度区域中流动的相似趋势。这项工作可以大大降低BFS流动问题中重新连接长度预测的计算成本，并显示出获得独立于网格的解时湍流模型的执行程度如何。结果发现，采用的湍流模型的预测再附着长度与实验吻合得很好，被认为是与网格无关的解决方案。风洞中计算域的可视化显示了在重新连接长度区域中流动的相似趋势。这项工作可以大大降低BFS流动问题中重新连接长度预测的计算成本，并显示出获得独立于网格的解时湍流模型的执行程度如何。