We consider the protruding cube (II/d = 0.3), as it is a realistic model for an unstable stone. The horizontal pressure gradient (both mean and fluctuating) was much larger than the vertical gradient. This means that drag is probably the main cause of entramment, although the angle of repose and the exposed areas of the stone still have to be incorporated in the analysis. Fluctuating lift might be necessary for the entrainment if the angle of repose is high (smaller particles). Near the cube extreme values of u' coincides with the largest Δp'_D. At higher elevations in the flow (y = 54 mm) sweeps coincide with larger Δp'_D than extreme values of u'. It must be mentioned that the type of flow structure leading to a "sweep" (Q_4-event) near a rough bed is not clearly defined at present, contrary to the smooth bed case. Flow configurations with an altered turbulence structure will be studied as well. A PIV installation is being set up for measurements of entire flow fields.
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机译：我们考虑突出的立方体（II / D = 0.3），因为它是一个不稳定的石头的现实模型。水平压力梯度（均值和波动）远大于垂直梯度。这意味着阻力可能是珊瑚丛的主要原因，尽管休息角和石材的暴露区域仍然必须在分析中结合。如果恢复角度高（较小的颗粒），则夹带可能需要波动升降机。与最大ΔP'_d相一致的立方体极值靠近。在流动（Y = 54mm）的较高升高处，扫描与比U'的极值相一致Δp'_d。必须提到它目前不明确地定义导致粗糙床附近的“扫描”（Q_4-事件）的流动结构的类型，这与光滑的羽毛壳相反。还将研究具有改变的湍流结构的流量配置。正在设置PIV安装以进行整个流场的测量。
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