title: A new instrument for dynamic helical squeeze flow which superposes oscillatory shear and oscillatory squeeze flow.
abstract: Simple shear flow has been widely used as a model flow system to investigate the rheological properties of complex fluids. Although it is useful and easy to apply, the shear flow is too simple compared with the complicated flows encountered in real processes. For this reason, it is necessary to study the rheological properties of viscoelastic fluids subjected to more complicated flow field. In this paper, we report a new instrument in which dynamic helical squeeze flow is generated. It superimposes the oscillatory squeeze flow on the oscillatory shear flow, and was designed to get more information on the microstructural change of complex fluids in the flow field which is more complex than conventional simple shear but is still well-defined. This instrument has advantages: the shear and normal stresses can be obtained simultaneously under the coupled flow field; the present design can be used to investigate the structural anisotropy in the direction of both rotational and vertical motion. This study provides a new design and methodology to investigate the rheological responses of complex fluids under dynamic helical squeeze flow.
authors.affiliation: School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, Seoul 151-744, Korea.
authors.forename: Jae Hee
authors.initials: JH
authors.lastname: Kim
authors.forename: Kyung Hyun
authors.initials: KH
authors.lastname: Ahn