Determining the hydrodynamic force acting on bubbles and particles moving parallel to a wall in a shear flow is a problem of fundamental importance, as this configuration is involved in a variety of technical and natural systems. The presence of the wall tends to increase the drag force, and more importantly causes a transverse lift force acting on the body. This thesis focuses on extending the current capability in predicting drag and lift forces on spherical bubbles and particles translating in a linear shear flow, primarily in the vicinity of a wall, and obtaining quantitative insight into the interaction mechanisms at work in the context of finite sphere Reynolds number. The investigations are performed through direct numerical simulation (DNS) using an accurate finite volume method.
The first part of the thesis summarizes all expressions for the drag and lift forces available in the literature. A comprehensive review of existing results from analytical, experimental, and direct numerical simulation studies is given. The available correlations are critically assessed by comparison to data from these studies. Based on the comparison, recommendations are given which correlations to use including some new proposals, and gaps in the data are identified.
The second part aims to fill the gaps mentioned above by means of DNS. Specifically, the three-dimensional flow around a non-rotating sphere translating steadily in a wall-bounded linear shear flow is investigated by solving the full Navier-Stokes equations. Numerical results and analytical expressions are combined to provide accurate semi-empirical expressions for the drag and lift forces at arbitrary Reynolds number and separation distance.
Present numerical results help to rationalize and quantify the various mechanisms at work and the ways they interact. From a practical point of view, they also result in several closure models for the drag correction and transverse force, which are necessary inputs in the point-particle based Eulerian-Lagrangian simulations or in Eulerian-Eulerian simulations based on the interpenetrating continua concept.:1 INTRODUCTION
1.1 Background
1.2 Underlining mechanisms
1.3 State of the art
1.4 Motivation, goal and outline of the thesis
2 STATE OF THE ART
2.1 Statement of the problem
2.2 Overview of literatures
2.3 Unbounded linear shear flow
2.4 Linear shear flow with the wall lying in the inner region
2.5 Stagnant flow with the wall lying in the outer region
2.6 Linear shear flow with the wall lying in the outer region
2.7 Conclusions
3 NUMERICAL APPROACH AND PRELIMINARY TESTS
3.1 Numerical approach
3.2 Preliminary tests
4 CLEAN SPHERICAL BUBBLE IN WALL-BOUNDED FLOW
4.1 Characteristics of the flow field and fundamental mechanisms
4.2 Hydrodynamic forces on the bubble: fluid at rest at infinity
4.3 Hydrodynamic forces on the bubble: linear shear flow
4.4 Conclusions
5 RIGID SPHERE IN WALL-BOUNDED FLOW
5.1 Characteristics of the flow field and fundamental mechanisms
5.2 Hydrodynamic forces on the sphere: fluid at rest at infinity
5.3 Hydrodynamic forces on the sphere: Linear shear flow
5.4 Conclusions
6 CONCLUSIONS AND FUTURE WORK
6.1 Summary and conclusions
6.2 Future work
7 REFERENCE
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:74247 |
| Date | 26 March 2021 |
| Creators | Shi, Pengyu |
| Contributors | Hampel, Uwe, Legendre, Dominique, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 10.1103/PhysRevFluids.5.073601, 10.1016/j.ces.2019.115264, 10.1016/j.ces.2019.08.003 |
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