Computations of breakup modes in laminar compound liquid jets in a coflowing fluid |
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| Institution: | 1. Graduate School of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan;2. Division of Materials Science, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan;3. Department of Aerospace and Mechanical Engineering, The University of Notre Dame, Notre Dame, IN 46556-5684, USA;1. Hanoi University of Science and Technology, Vietnam;2. Notre Dame University, USA;3. Saitama University, Japan;4. Ritsumeikan University, Japan;1. School of Hydraulic, Energy and Power Engineering, Yangzhou University, Yangzhou, Jiangsu 225127, PR China;2. Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, Jiangsu 210096, PR China;3. State Key Laboratory of Bioelectronics, Southeast University, Nanjing, Jiangsu 210096, PR China;4. Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application, School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, PR China;1. School of Transportation Engineering, Hanoi University of Science and Technology, 1 Dai Co Viet, Hai Ba Trung, Hanoi, Viet Nam;2. Department of Aerospace and Mechanical Engineering, The University of Notre Dame, Notre Dame, IN 46556-5684, USA;3. Division of Materials Science, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan;4. Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan |
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| Abstract: | We present a numerical investigation of breakup modes of an axisymmetric, laminar compound jet of immiscible fluids, which flows in a coflowing immiscible outer fluid. We use a front-tracking/finite difference method to track the unsteady evolution and breakup of the compound jet, which is governed by the Navier–Stokes equations for incompressible Newtonian fluids. Numerical results show that depending on parameters such as the Reynolds number Re (in the range of 5–30) and Weber Number We (in the range of 0.1–0.7), based on the inner jet radius and inner fluid properties, the compound jet can break up into drops in various modes: inner dripping–outer dripping (dripping), inner jetting–outer jetting (jetting), and mixed dripping–jetting. Decreasing Re or increasing We promotes the jetting mode. The transition from dripping to jetting is also strongly affected by the velocity ratios, U21 (intermediate to inner velocities) and U31 (outer to inner velocities). Increasing U21 makes the inner jet thinner and stretches the outer jet and thus promotes jetting. In contrast, increasing U31 thins the outer jet, and thus, when the inner jet is dripping, the outer jet can break up into drops in the mixed dripping–jetting mode. Continuously increasing U31 results in thinning both inner and outer jets and thus produces small drops in the jetting mode. In addition, starting from dripping, a decrease in the interfacial tension ratio of the outer to inner interfaces results in the mixed dripping–jetting and jetting modes. These modes produce various types of drops: simple drops, and compound drops with a single inner drop (single-core compound drops) or a few inner drops (multi-core compound drops). |
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