  The impact of fluid drops on solid substrates has widespread interest in
ink-jet printing, agricultural pesticides, and many other coating and spraying
applications due to its relevance to a variety of industrial processes. Drop
impact dynamics has been an active field of soft-matter research for over a
century. A large body of experimental and theoretical work has been done to
understand the impact dynamics of Newtonian fluids, yet we are far from
understanding the drop impact of complex fluids. In this review, we outline
recent experimental, theoretical, and computational advances in the study of
impact dynamics of complex fluids on solid surfaces. Here, we provide an
overview of this field, with our discussion segmented by rheological behavior.
Throughout, we highlight promising future directions, as well as ongoing
experimental and theoretical challenges in the field.
