1 General Introduction -- 2 Microscopic Formulation of Two-Phase Flows -- 3 Macroscopic Formulation of Two-Phase Flows: the Two-Fluid Model -- 4 Surface Equations for Two-Phase Flows -- 5 Population Balances and Moments Transport Equations for Disperse Two-Phase Flows -- 6 Turbulence Equations for a Continuous Phase -- 7 Turbulence Equations for a Disperse Phase -- 8 Interfacial Forces and Momentum Exchange Closure -- 9 Interfacial Heat and Mass Transfers -- 10 Closures for the Bubble Size Distribution and Interfacial Area Concentration -- 11 Turbulence Models -- 12 Example of Application: Bubbly Flow in a Vertical Pipe -- Appendix A -- Appendix B -- Appendix C -- Appendix D -- Appendix E -- Appendix F -- Index.