OP-II-3

OP-I-19and slug dimensions, formation time and film thickness. This study aims to achievethis purpose and additionaly, it aims to understand the effect of nozzle displacementinside the capillary, as until now only the effect of dimensions of the nozzle wasstudied. The 3D CFD simulations were performed using VOF technique for lowCapillary number of 0.0016 for a 1.0 mm square cross sectioned minichannel using anozzle of 0.6 o.d. and 0.315 i.d. Various capillary contact angles from 0 to 90degrees were studied for a centered nozzle and for a selected contact angle, theeffect of nozzle displacement were studied by changing the place of the nozzle, andfor a specific contact angle, the 3D simulations were validated with the experimentsin terms of bubble and slug dimensions and bubble formation time. It is shown thatthe contact angle has significant effect not only on bubble formation time but also onfilm thickness, and bubble and slug lengths.Figure 1 shows a snapshot for two different contact angles and their effets onbubble and slug lengths as well as the film thickness around the gas bubble.Figure 1. Snapshots of hydrogen and alpha-methylstyrene two-phase flow inside theminichannel for the contact angle of 0 (top) and 60 (bottom) degrees at the capillary numberof 0.0016. The direction of flow is from left to the right.References[1]. Angeli, P. and A. Gavriilidis, Hydrodynamics of Taylor flow in small channels: a review.Proceedings of the Institution of Mechanical Engineers, Part C: Journal of MechanicalEngineering Science, 2008. 222(5): p. 737-751.[2]. Mogalicherla, A.K. and D. Kunzru, Effect of Gas and Liquid Superficial Velocities on thePerformance of Monolithic Reactors. Industrial & Engineering Chemistry Research 2010.49(4):p.1631-1641.[3]. Chen, Y., R. Kulenovic, and R. Mertz, Numerical study on the formation of Taylor bubbles incapillary tubes. International Journal of Thermal Sciences, 2009. 48(2): p. 234-242.[4]. Shao, N., et al., CFD simulations of the effect of inlet conditions on Taylor flow formation.International Journal of Heat and Fluid Flow, 2008. 29(6): p. 1603-1611.[5]. Goel, D. and V.V. Buwa, Numerical Simulations of Bubble Formation and Rise in Microchannels.Industrial & Engineering Chemistry Research, 2008. 48(17): p. 8109-8120.[6]. Han, Y. and N. Shikazono, Measurement of liquid film thickness in micro square channel.International Journal of Multiphase Flow, 2009. 35(10): p. 896-903.AcknowledgementsThe authors are grateful to Deutsche Forschungsgemeinschaft (DFG) for financialsupport of the research project.73