NUMERICAL-SIMULATION OF TIME-DEPENDENT THERMOCAPILLARY CONVECTION IN LAYERED FLUID SYSTEMS

We consider steady and time-dependent thermocapillary convection in en capsulated layers of moderate Prandtl number fluids. Assuming flat fre e surfaces and fluid/fluid interfaces, the two-dimensional, time-depen dent Navier-Stokes equations and the energy equation are integrated by a time-accurate method on a stretched, staggered mesh, particular att ention is focused on the nature of time dependence in water encapsulat ion of Fluorinert FC-75 and in ethylene glycol encapsulated by FC-75 a nd hexadecane, We show that similar mechanisms for time-dependent ther mocapillary convection exist for single-layer and multiple-layer fluid systems, and that shear effects at a thermocapillary interface can re duce convection in an encapsulated fluid layer. Based on our estimates for the thermal coefficients of interface tension, an apparent benefi t of fluid encapsulation is to lessen the tendency toward time depende nce.