Two-Layer Bingham Fluid under Permanent Wave
Date Issued
2014
Date
2014
Author(s)
Cao, Wei-Min
Abstract
Debris flow disaster has become one of the major reasons for slope land disaster. If the debris bed has enough shear stress, it will carry more sediments and cause damages to downstream area. According to different moisture and grain size, debris flow has many categories. We chose one of the categories which called mud fluids to do research, and used Bingham fluid model to describe the flow characteristics.
In this study, we let the bed of sloping channel has one step geometry shape. One layer of saturated mud fluid which defined as fluid 2 was fully deposited in the rectangular cavity of step, the height of deposit and cavity is the same so could be regarded as an arbitrary deposit region. Next we let another layer of mud fluid came from upstream channel which defined as fluid 1. When it contact with fluid 2, if the shear stress below fluid 1 is strong enough, fluid 2 will be carried. So according to the characteristics of yield stress of Bingham fluid model, the whole research region could be separated to three layers. From up to down direction ( free surface to channel bed direction) : plug layer of fluid 1、shear layer of fluid 1、shear layer of fluid 2. In addition, we assume fluid and fluid both have different characteristics and rheology. Because the different density can cause density stratification, we also suppose the fluid and fluid will not be blended.
We used the two dimensional, unsteady , nonuniform, imcompressible continuity and momentum equations with long wave theory to do derivation、dimensional analysis、normalization and numerical calculation. Afterward, analyzed the interaction between fluid and fluid , and the flow situation after fluid 2 be carried. The major purpose is to find out the change of free surface and (fluid 1/ fluid 2)interface with time and space, and the influence from other parameters.
Subjects
賓漢流體
恆定波
底床變動
Type
thesis
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