The reorientation and settling of a liquid/gas interface in a right circular cylinder upon step reduction in gravity is investigated numerically. A modified dynamic contact angle boundary condition is implemented where the hysteresis parameter gamma is employed as an adjustable parameter representing the degree of relative slip at the contact line. The effect of the boundary condition on the axial interface oscillation is studied and the dependence thereon of the resonant frequency and settling time is given. Results are shown regarding the behavior of the dynamic contact angle and the penetration of the surface oscillations into the bulk liquid. The numerical results are tuned via comparisons with existing experimental data, and a method for estimating the appropriate boundary condition providing good agreement is suggested. An accompanying scale analysis depicts gamma as a function of the Ohnesorge number, the cylinder radius, and the static contact angle, These independent parameters are measures of the system damping, characteristic surface deflection, and effective stiffness of the interface, Applications of the results may be made to spacecraft fluids management and the use of spacecraft and/or drop towers for fluids experimentation.
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