Abstract:

Large-amplitude nonlinear oscillations of a water drop, radius 2.53 cm and aspect ratio 2.10, with surfactant BSA (bovine serum albumin) 1.0x10[sup -5] g/ml(1CMC), is numerically simulated based on the boundary integral method. BSA is a globular, large molecular-weight protein. Two surface viscosities, surface dilatational viscosity and surface shear viscosity, as well as the Marangoni effect, are considered. The high-surface viscosities make the rotational velocity the same order as the irrotational velocity in the boundary layer. A boundary-layer method is used to calculate the rotational velocity. When the surface dilatational viscosity is 0.5 sp and the surface shear viscosity is 0.15 sp, the numerical simulation results are in good agreement with the experiment results observed in the space shuttle during the second United States Microgravity Laboratory, USML-2, on October, 1995. The evolution of the drop oscillation for both experiment and simulation is given. The change of the BSA distribution along the surface, and the relative importance of the rotational and irrotational velocities, as the drop oscillates is also shown. [Work supported by NASA through JPL, Contract No. 958722.]