  Fluid turbulence is commonly associated with stronger drag, greater heat
transfer, and more efficient mixing than in laminar flows. In many natural and
industrial settings, turbulent liquid flows contain suspensions of dispersed
bubbles and light particles. Recently, much attention has been devoted to
understanding the behavior and underlying physics of such flows by use of both
experiments and high-resolution direct numerical simulations. This review
summarizes our present understanding of various phenomenological aspects of
bubbly and buoyant particle-laden turbulent flows. We begin by discussing
different dynamical regimes, including those of crossing trajectories and
wake-induced oscillations of rising particles, and regimes in which bubbles and
particles preferentially accumulate near walls or within vortical structures.
We then address how certain paradigmatic turbulent flows, such as homogeneous
isotropic turbulence, channel flow, Taylor-Couette turbulence, and thermally
driven turbulence, are modified by the presence of these dispersed bubbles and
buoyant particles. We end with a list of summary points and future research
questions.
