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

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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.