NUMERICAL SIMULATION OF THREE DIMENSIONAL OSCILLATORY FLOW IN HALF-ZONE BRIDGES OF LOW Pr FLUIDS
Nobuyuki Imaishi1, Shouich Yasuhiro1 and Shinichi Yoda2
1Institute of Advanced Material Study, Kyushu University, Kasuga, 815-8580
2NASDA, Sengen 2-1-1, Tsukuba 305-8505
A set of numerical simulations was conducted to understand characteristics of oscillatory Marangoni convection in half-zone liquid bridges with various aspect ratios (from 0.6 to 2.2) and Prandtl numbers (from 0 to 0.02) by a finite difference method. The simulation results indicated that under smaller temperature differences the flow in the liquid bridge is axisymmetric but it becomes unstable against a three dimensional disturbance beyond a certain threshold value of temperature difference. The flow becomes steady three dimensional.
This steady flow becomes unstable against time dependent three dimensional disturbances beyond a second critical condition. The numerical simulations revealed the critical conditions, 3-D structure of disturbances and oscillation modes. The first critical conditions showed good agreements with those of linear stability analyses. The second critical conditions also agreed with previous values and gave new critical values for wide range of aspect ratio. Based on these simulations, a flow map was proposed for Pr=0 fluid. Critical Reynolds numbers, flow mode and types of oscillations were also determined for Pr=0.01 and 0.02 fluids.
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