Investigation on Flow Characteristics and Entrainment for lnclined Thermals as well as the Front of lnclined Strating Plumes

本文对沿斜坡向下运动的二维守恒重力流，即倾斜起动羽流和倾斜热气流进行了理论和实验研究，在理论研究中，建立了倾斜热气流和倾斜起动羽流的积分模型。所提出的模型包含了所涉及的主要物理原理。在实验研究中，通过对倾斜热气流和倾斜起始羽流的实验研究，定量分析了倾斜羽流的几何形状、形状因子、空间增长率、初始羽流的速度、密度、密度等重要的流动特性，并对倾斜起始羽流和倾斜热气流的流动特性进行了研究。前传播速度和气流的卷吸作用。从大量现有实验数据的应用中发现，这些流动特性在rheta=5-90 °范围内最多是底部倾斜角rheta的函数，因此，被量化为rheta的函数。在倾斜角rheta=5-90 °范围内，倾斜热气流和倾斜初始羽流的流动特性除前缘传播速度外，无显著差异。理论和实验还发现，前缘传播速度U_f、流动厚度H_f、在倾斜热气流中，纵向距离x上的平均浮力B_f与x，H_f-x，B_f-x^成U_f=常数，<-1>而在倾斜起始羽流前缘，U_f-x^&lt;-1/2&gt;，H_f-x，B_f-x^<-2>成U_f=常数。

Miscible conservative two-dimensional gravity currents traveling downslope, namely, inclined starting plumes and inclined thermals were investigated theoretically and experimentally.In theoretical study, integral models were formulated for inclined thermals and inclined starting plumes. The proposed models incorporate the maior physical principles involved. For a wide range of practical applications, respective model is capable of predicting such plume or thermal characteristics as flow thickness, velocity, and density with higher accuracy than any available models.In Experimental study, a series of extensive laboratory experiments for inclined thermals and inclined starting plumes were conducted to quantify a number of important flow characteristics, including the geometry, shape factors, spatial growth rates, front propagation speeds, and entrainment functions of the flows. It is found from the application of a large volume of present experimental data that these flow characteristics are at most functions of bottom slope angle rheta for the range of rheta=5-90ﾟ and, consequently, were quantified as functions of rheta. It is also found that, except front propagation speed, no significant differences are identified regarding the flow characteristics between inclined thermals and the front of inclined starting plumes for the range of bottom slope angle rheta=5-90ﾟ.It is also found theoretically and experimentally that the dependence of the front propagation speed U_f, flow thichness H_f, and mean buoyancy B_f on longitudinal distance x are U_f=constant with x, H_f-x, and B_f-x^<-1> in inclined thermals, whereas U_f-x^<-1/2>, H_f-x, B_f-x^<-2> in the front of inclined starting plumes.