Defying the classical definitions of solids and liquids, complex fluids include polymers, colloids, emulsions, foams, gels, liquid crystals, surfactants, and other materials that form flowable microstructures. They are vital to industries that produce polymers (e.g., plastic packaging), colloids (paint), foods (ketchup), and consumer products (toothpaste and shampoo), and are also used in countless other products manufactured by the petroleum, microelectronics,...