title: Drag reduction by microbubbles in turbulent flows: the limit of minute bubbles.
abstract: Drag reduction by microbubbles is a promising engineering method for improving ship performance. A fundamental theory of the phenomenon is lacking, however, making actual design quite haphazard. We offer here a theory of drag reduction by microbubbles in the limit of very small bubbles, when the effect of the bubbles is mainly to normalize the density and the viscosity of the carrier fluid. The theory culminates with a prediction of the degree of drag reduction given the concentration profile of the bubbles. Comparisons with experiments are discussed and the road ahead is sketched.
authors.affiliation: Department of Chemical Physics, The Weizmann Institute of Science, Rehovot, 76100 Israel.
authors.forename: Victor S
authors.initials: VS
authors.lastname: L'vov
authors.forename: Anna
authors.initials: A
authors.lastname: Pomyalov
authors.forename: Itamar
authors.initials: I
authors.lastname: Procaccia
authors.forename: Vasil
authors.initials: V
authors.lastname: Tiberkevich