title: Forced versus Spontaneous Spreading of Liquids.
abstract: Two sets of experiments are performed, one for the free spreading of a liquid drop on a glass substrate and the other for the forced motion of a glass plate through a gas-liquid interface. The measured macroscopic advancing contact angle, θA, versus the contact line speed, U, differ markedly between the two configurations. The hydrodynamic theory (HDT) and the molecular kinetic theory (MKT) are shown to apply separately to the two systems. This distinction has not been previously noted. Rules of thumb are given that for an experimentalist involve a priori knowledge of the expected behavior.
authors.affiliation: Department of Mechanical and Aerospace Engineering, Complex Fluids and Interfacial Physics Laboratory, University of California at Los Angeles , Los Angeles, California 90095, United States.
authors.forename: A
authors.initials: A
authors.lastname: Mohammad Karim
authors.affiliation: Department of Engineering Sciences and Applied Mathematics, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: S H
authors.initials: SH
authors.lastname: Davis
authors.affiliation: Department of Mechanical and Aerospace Engineering, Complex Fluids and Interfacial Physics Laboratory, University of California at Los Angeles , Los Angeles, California 90095, United States.
authors.forename: H P
authors.initials: HP
authors.lastname: Kavehpour