Complicated terrain was considered and simplified as two-dimensional (2D) terrain in a dynamical downscaling model and a parametric wind field model for typhoons developed by the Shanghai Typhoon Institute. The 2D terrain was further modeled as uphill and downhill segments with various slope angles relative to the incoming flow. The wind speed ratios and pressure characteristics around the 2D terrain were numerically and experimentally investigated in this study. Aerodynamic characteristics of the 2D terrain with a limited-length upper surface were first investigated in the wind tunnel with sheared incoming flow. The corresponding numerical investigation was also conducted by using the commercial computational fluid dynamics code FLUENT with the realizable k-ε turbulence model. Special efforts were made to maintain the inflow boundary conditions throughout the computational domain. Aerodynamic characteristics were then investigated for the ideal 2D terrain with an unlimited-length upper surface by using a numerical method with uniform incoming flow. Comparisons of the different terrain models and incoming flows from the above studies show that the wind pressure coefficients and the wind speed ratios are both affected by the slope angle. A negative peak value of the wind pressure coefficients exists at the escarpment point, where flow separation occurs, for the uphill and downhill terrain models with slope angles of 40° and 30°, respectively. Correspondingly, the streamwise wind speed ratios at the points above the escarpment point for the uphill terrain model increase with increasing slope angle, reach their peak values at the slope angle of α = 40° and decrease when the slope angle increases further. For the downhill terrain model, similar trends exist at the points above the escarpment point with the exception that the critical slope angle is a = 30°.

中文翻译：

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坡度不同的二维地形周围空气动力特性的数值和实验研究

在上海台风研究所开发的动力降尺度模型和台风参数风场模型中，复杂地形被考虑并简化为二维（2D）地形。将2D地形进一步建模为上坡和下坡路段，相对于流入水流具有不同的倾斜角度。在此研究中，对二维地形周围的风速比和压力特性进行了数值和实验研究。首先在风道中采用剪力流来研究具有有限长度的上表面的二维地形的空气动力学特性。还使用具有可实现的k - ε的商业计算流体力学代码FLUENT进行了相应的数值研究。湍流模型。为了保持整个计算域的流入边界条件，我们做出了特殊的努力。然后，通过采用均匀流入流的数值方法，对具有无限长度上表面的理想2D地形的空气动力学特性进行了研究。通过以上研究对不同地形模型和入流的比较表明，风压系数和风速比均受坡角的影响。对于分别具有40°和30°倾斜角的上坡和下坡地形模型，在出现流分离的陡峭点处，风压系数的负峰值存在。相应地，对于上坡地形模型，在悬崖点上方的点处的流向风速比随坡角的增加而增加，α = 40°，当倾斜角进一步增加时减小。对于下坡地形模型，在陡坡点以上的点处存在相似的趋势，但临界坡度角为a = 30°。