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<p>In this study, the effect of width ratio (branch channel width/main channel width) on droplet breakup dynamics in a horizontal microfluidic T-junction using oil–water volume fraction contours, pressure profile, and velocity profile has been investigated using 2D simulation. Simulations have been also conducted to reveal the effect of branch arm length ratio (right arm length/left arm length) on droplet breakup dynamics. The numerical simulation is validated with experimental results taken from the literature. Two types of breakup regimes, along with a non-breakup regime, have been found. The breakup regimes are tunnel breakup, and obstructed breakup, and the non-breakup regime is the alternate movement of droplets. The tunnel breakup and the obstructed breakup are mainly due to the pressure difference in the branch channel and the direction of the velocity vectors which are towards the branch’s exit and the pressure swing phenomenon is the reason behind the alternate movement of the droplets. Breakup with tunnel is found in WR (width ratio) = 0.75, 0.5, breakup with obstruction is found in WR (width ratio) = 0.25 and alternate movement is found in WR (width ratio) = 1 for V<sub>w</sub> (velocity of water) = 0.01&#xa0;m/s, V<sub>o</sub> (velocity of oil) = 0.18&#xa0;m/s. It has been found that breakup tendency increases as we decrease the width ratio (1, 0.75, 0.5, and 0.25) and increase the arm length ratio (0.4, 0.6, and 0.9). Some 3D simulations have been performed regarding these and the 3D simulations confirm the accuracy of the 2D simulations. Droplet breakup conditions have been studied. Various mixed flow regimes have been identified and illustrated. Mixed flow patterns have been displayed with the help of a flow pattern map for the width ratio = 1, 0.75, 0.5, and 0.25. Prediction of simulated pressure gradient have also been done with the help of the Dimensional analysis for width ratio = 1 and 17% of average error is found between predicted and simulated pressure gradient. This quantitative analysis of the pressure drop evidenced that the solver correctly captures viscous dissipation and interfacial forces and the design of bifurcated channel geometry is optimal.</p>

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Influence of microchannel geometry on droplet breakup dynamics: a computational study

  • 期刊论文

  • 发表日期：

    2025年9月10日

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  • Saikat Biswas,
  • Partho S. G. Pattader,
  • Tapas K. Mandal

摘要

In this study, the effect of width ratio (branch channel width/main channel width) on droplet breakup dynamics in a horizontal microfluidic T-junction using oil–water volume fraction contours, pressure profile, and velocity profile has been investigated using 2D simulation. Simulations have been also conducted to reveal the effect of branch arm length ratio (right arm length/left arm length) on droplet breakup dynamics. The numerical simulation is validated with experimental results taken from the literature. Two types of breakup regimes, along with a non-breakup regime, have been found. The breakup regimes are tunnel breakup, and obstructed breakup, and the non-breakup regime is the alternate movement of droplets. The tunnel breakup and the obstructed breakup are mainly due to the pressure difference in the branch channel and the direction of the velocity vectors which are towards the branch’s exit and the pressure swing phenomenon is the reason behind the alternate movement of the droplets. Breakup with tunnel is found in WR (width ratio) = 0.75, 0.5, breakup with obstruction is found in WR (width ratio) = 0.25 and alternate movement is found in WR (width ratio) = 1 for Vw (velocity of water) = 0.01 m/s, Vo (velocity of oil) = 0.18 m/s. It has been found that breakup tendency increases as we decrease the width ratio (1, 0.75, 0.5, and 0.25) and increase the arm length ratio (0.4, 0.6, and 0.9). Some 3D simulations have been performed regarding these and the 3D simulations confirm the accuracy of the 2D simulations. Droplet breakup conditions have been studied. Various mixed flow regimes have been identified and illustrated. Mixed flow patterns have been displayed with the help of a flow pattern map for the width ratio = 1, 0.75, 0.5, and 0.25. Prediction of simulated pressure gradient have also been done with the help of the Dimensional analysis for width ratio = 1 and 17% of average error is found between predicted and simulated pressure gradient. This quantitative analysis of the pressure drop evidenced that the solver correctly captures viscous dissipation and interfacial forces and the design of bifurcated channel geometry is optimal.