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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 47366 (08)
- University: Sharif University of Technology
- Department: Mechanical Engineering
- Advisor(s): Moosavi, Ali
- Abstract:
- Drag reduction on surfaces always has been a great case of study, especially in transport industry. This project discusses the external laminar flow of a single-phase fluid over a flat plate and the effects of making rectangular tiny grooves - in micron or millimeter - on them to reduce total drag. Making grooves with appropriate geometry on surfaces causes the fluid-solid contact area on the groove's surface turn into fluid-fluid and as a result the fluid will not shed into the groove. In other words the flow instead of having a no-slip boundary condition on inner surfaces of the groove, creates vortices in them that causes a remarkable reduction in velocity gradient followed by a skin friction drag coefficient reduction on the whole surface. On the other hand creating vortices in the grooves and separation of the flow causes a remarkable increase in pressure drag coefficient. So total drag reduction phenomenon by making grooves on flat plates critically depends on choosing appropriate geometry that covers the basic procedure of current study. Since these grooves are at mesoscopic scale, we have chosen Lattice-Boltzmann method for simulation that is a very simple and time conserving method and also has a great flexibility to various forms of flows. Here we should emphasis on the fact that this form of simulation – drag reduction study for external flow over a rectangular plate by lattice-boltzmann method - has not been done before and similar studies mostly concern flows in channels or are experimental or do the simulation process on macroscopic scale. For starting simulation on this project, after reaching mesh independency, the effect of groove geometry on drag reduction percentage is investigated. Finally with optimizing the geometry and choosing appropriate width and depth for grooves we can reduce total mean drag coefficient up to 7% in this study
- Keywords:
- Reynolds Number ; Lattice Boltzmann Method ; Vortex Generator ; Total Mean Drag Coefficient ; Optimizing Groove Geometry
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