title: Bulk viscosity in the case of the interatomic potential depending on density.
abstract: We derive a formula for the bulk viscosity zeta in a density-dependent-potential system. This is a generalization of the bulk-viscosity formula for the density-independent-potential system which has been proposed recently by us. In our formulas, the bulk viscosity is expressed by using microscopic quantities such as interatomic potentials and pair distribution functions. This has an outstanding advantage of providing the relation between such microscopic information and a macroscopic quantity zeta. On the other hand, in all formulas proposed previously, zeta is expressed in terms of pressure, a macroscopic quantity, and it is difficult to discuss this relation. We apply our formula to a model liquid metal in which the interatomic potential varies with density. Our calculated results show that zeta increases in the density region where the interatomic potential changes from one type to another. These results agree qualitatively with the experimental results about liquid mercury.
authors.affiliation: Department of Applied Physics, School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. hokumura@ims.ac.jp
authors.forename: Hisashi
authors.initials: H
authors.lastname: Okumura
authors.forename: Fumiko
authors.initials: F
authors.lastname: Yonezawa