A Meniscus Instability of Non-Newtonian Fluid Between Parallel Circular Plates : 1st Report, Analysis by Linear Stability Theory

Abstract

Unstable phenomena of the meniscus between two circular parallel plates in negative motion were theoretically and experimentally studied. In the present paper, a local capillary number was newly defined by using several parameters of the non-Newtonian property of a power-law fluid, and the relations between the local capillary number and the wave number of disturbance were theoretically derived on the basis of the linear stability theory. The theoretical relations under the condition of neutral stability and that of the maximum amplification for disturbance were compared with the experimental results, and the validity of the stability criterion was shown and the best agreement was obtained with the wave number of maximum amplification.