CFD Modelling of Wall Film on a Generic Rear View Mirror
Typ
Examensarbete för masterexamen
Master Thesis
Master Thesis
Program
Publicerad
2011
Författare
Nassif, Charbel
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The ability to control water flow on solid surfaces is of great interest for the car manufacturer, due to the fact that maintaining the visibility on the side windows and rear side view mirrors will improve the active safety. Therefore, Volvo Cars Corporation (VCC) desires to utilize a numerical method to compensate the tests made in Volvo's PVT wind tunnel. A numerical simulation makes it possible to analyze the fluid flow problems in detail, allowing faster analysis occurring earlier in the design cycle than is possible with experiments, costing less money and lowering the risks involved in the design process. Thus, the goal with this project is to propose Computational Fluid Dynamic (CFD) methods for simulation of water accumulation on the vehicle exterior. A commercial code, Fluent, has been utilized for calculations of wall film modelling on a generic rear view mirror and validated with experimental data. The models used are the Lagrangian and the Eulerian wall film models. The former model uses Lagrangian particles to obtain the wall film and the latter uses a continuum phase to simulate the wall film. Both models have been computed as steady state and transient. When calculating Eulerian wall film model with a stationary flow field, the particles could either be track unsteady or steady, though for the Lagrangian wall film model the particles could only be tracked unsteady. The results show that the number of particles in the domain has the largest impact on the computational expenses, therefore the Eulerian wall film model, with its continuum phase for modelling wall film and steady particle tracking, is less computational expensive. Furthermore, the Eulerian wall film model has the physical models to model separation and wall film propagation and is not only dependent on the surface shear stresses unlike the Lagrangian wall film model. Therefore, the Eulerian wall film model is recommended to use when modelling wall film.
Beskrivning
Ämne/nyckelord
Hållbar utveckling , Transport , Strömningsmekanik , Sustainable Development , Transport , Fluid mechanics