The Gas-assisted Expelled Fluid Flow in the Front of a Long Bubble in a Channel

Abstract:- Investigated in this study is the steady-state flow field of a long bubble penetrating into a region filled with a viscous fluid confined by two closely located parallel plates. Instead of using the complicated procedure for iteratively computing the free surface and flow patterns, we simply use a theoretical profile of the bubble so that the influence of bubble shape on the flow field can be examined directly. Due to the simplification, flow fields with higher Reynolds number are easier to be included and different flow phenomenon is found. The numerical techniques employed are finite difference method (FDM) with successive over-relaxation (SOR). The simulation results show coincidently with others the two typical flow patterns (complete bypass flow and recirculation flow). The gradually moving of the stagnation point in the front of the bubble tip between two typical flow patterns is clearly presented and explainable. Both of the position of the stagnation point parallel and perpendicular to the flow, *spx and *spy, depends on Reynolds number, Re, and λ, the ratio of asymptotic bubble width to the distance between two parallel plates. As λ or Re increases, *spy increases too, but *spx decreases. A quasi-linear relationship between λ and *spx is found in a recirculation flow region. Be ware that the stagnation point is very sensitive with λ for Re>100. As Re increases, the maximum value of stream function increases, and the recirculation zone near the bubble tip becomes bigger too. maxψ Key-Words:- long bubble, expelled fluid flow, stagnation point, two-phase flow, inertia forces. 1