The pressure increases in concave curvatures of tunnel spillways due to the flow's rotational acceleration. Physical models are the best tools to analyse this phenomenon. The number of physical models required to cover all practical prototype conditions is so large that this becomes impractical in terms of placement and costs. Therefore, Flow-3D software has been chosen to analyse the problem of turbulent flow in tunnels with concave curvatures covering all possible practical alternatives. Various tunnels with different discharges and geometries have been simulated by this software. The numerical results obtained by this software were verified using experimental results from the constructed physical model of Alborz dam tunnel spillway, and a satisfactory agreement was obtained. Moreover, it was found that roughness has a negligible influence on the bed pressure of the tunnel curvature. Dimensional analysis was used to reduce the number of variables involved and to obtain dimensionless parameters. The results obtained by the software were employed in the dimensionless parameters to develop a simple relationship with a correlation coefficient of 0.902 for the pressure at concave bends of tunnel spillways, in terms of the other variables involved, by using a curve-fitting technique.

中文翻译：

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使用湍流模型的隧道溢洪道凹弯压力的新关系

由于流动的旋转加速度，隧道溢洪道的凹曲率中的压力增加。物理模型是分析这种现象的最佳工具。覆盖所有实际原型条件所需的物理模型数量如此之大，以至于在布局和成本方面变得不切实际。因此，已选择 Flow-3D 软件来分析具有凹曲率的隧道中的湍流问题，涵盖所有可能的实际替代方案。该软件模拟了具有不同流量和几何形状的各种隧道。利用已构建的厄尔布尔士大坝隧道溢洪道物理模型的实验结果验证了该软件获得的数值结果，取得了令人满意的一致性。而且，结果发现，粗糙度对隧道曲率的床压影响可以忽略不计。量纲分析用于减少涉及的变量数量并获得无量纲参数。将软件得到的结果用于无量纲参数，利用曲线拟合技术，根据涉及的其他变量，建立了隧道溢洪道凹弯处压力的简单关系，相关系数为0.902。