Studies of Bubbly Channel Flows by Direct Numerical Simulations
Recent DNS studies of buoyant bubbly flows in vertical channels are discussed. Simulations of nearly spherical bubbly flows in vertical channels show that the bubbles move towards the walls for upflow and away from the walls for downflow in such a way that the core is in hydrostatic equilibrium. For downflow the wall-layer is free of bubbles but for upflow there is an excess of bubbles in the wall-layer. The liquid velocity in the core is nearly uniform. For laminar downflow the velocity in the wall-layer can be computed analytically and for turbulent flow the velocity is given (almost) by the law of the wall. For upflow the velocity in the wall-layer is strongly influenced by the presence of the bubbles. We conclude by discussing briefly bubble coalescence and topology induced flow regime changes.
KeywordsDirect Numerical Simulation Void Fraction Multiphase Flow Bubble Size Lift Force
Unable to display preview. Download preview PDF.
- Deckwer, W.-D.: Bubble Column Reactors. In: Field, R.W. (ed.) Translated by Cottrell, V. John Wiley and Sons Inc., Chichester (1992)Google Scholar
- Delhay, J.M.: Handbook of Multiphase Systems. In: Hetsroni, G. (ed.). Hemisphere-McGraw Hill, New York (1982)Google Scholar
- Drew, D.A., Passman, S.L.: Theory of Multicomponent Fluids. Springer, Heidelberg (1999)Google Scholar
- Esmaeeli, A., Tryggvason, G.: A DNS study of the buoyant rise of bubbles at O(100) Reynolds numbers. Physics of Fluids 17(093303), 19 pages (2005)Google Scholar
- Furusaki, S., Fan, L.-S., Garside, J.: The Expanding World of Chemical Engineering, 2nd edn. Taylor & Francis, Abington (2001)Google Scholar
- Hewitt, G.F., Roberts, D.N.: Studies of two-phase flow patterns by simultaneous X-ray and flash photography. UKAEA Report AERE-M2159 (1969)Google Scholar
- Lopez-De-Bertodano, M., Lahey Jr., R.T., Jones, O.C.: Development of a k-ε model for bubbly two-phase flow. J. Fluids Engineering 13, 327–343 (1987)Google Scholar
- So, S., Morikita, H., Takagi, S., Matsumoto, Y.: Laser Doppler velocimetry measurement of turbulent bubbly channel flow. Experiments in Fluids 33, 135–142 (2002)Google Scholar
- Wallis, G.B.: One-dimensional Two-phase Flow. McGraw-Hill, New York (1969)Google Scholar