A numerical study on flow and drag phenomena of spheroid bubbles in Newtonian and shear-thinning power-law fluids
A numerical study on flow and drag phenomena of spheroid bubbles in Newtonian and shear-thinning power-law fluids
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DOI：
10.1080/02286203.2016.1142287
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发表时间：
2015-04
影响因子：
3.1
通讯作者：
A. Gollakota;N. Kishore
中科院分区：
文献类型：
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作者：
A. Gollakota;N. Kishore
摘要利用基于计算流体动力学的数值求解器ANSYS Fluent 14，研究了雷诺数、球形气泡的纵横比和剪切稀化液体的幂律行为指数对球形气泡流动和阻力行为的影响。通过详细的域和网格独立性的研究，并通过比较目前的结果，在牛顿和剪切变稀幂律流体的球形气泡与他们的文学同行的解决方案的方法是广泛的基准。进一步广泛的新的结果报告在广泛的相关条件如下：雷诺数，Re：1 - 200;长径比的球状气泡，e：0.5 - 2.5，和幂律行为指数，n：0.2 - 1。再循环尾流的大小随着幂律指数的减小和/或气泡纵横比的减小和/或雷诺数的减小而减小。对于长径比e > 1的气泡，在幂律指数下存在一个交叉雷诺数，即在交叉雷诺数以下，气泡的阻力系数随幂律指数的减小而增大;而在交叉雷诺数以上，阻力系数随幂律指数的减小而减小。最后，基于数值计算结果，提出了一个简单的球形气泡在牛顿流体和幂律流体中上升的总阻力系数的预测关联式，该关联式可用于新的应用领域。
Abstract Effects of the Reynolds number, aspect ratio of spheroid bubbles, and power-law behavior index of shear-thinning liquids on the flow and drag behavior of spheroid bubbles are elucidated using a computational fluid dynamics-based numerical solver, ANSYS Fluent 14. The solution methodology is extensively benchmarked via detailed domain and grid independence study and by comparing present results of spherical bubbles in Newtonian and shear-thinning power-law fluids with their literature counterparts. Further extensive new results are reported over a wide range of pertinent conditions as follows: Reynolds number, Re: 1 – 200; aspect ratio of spheroid bubbles, e: 0.5 – 2.5, and power-law behavior index, n: 0.2 – 1. The size of the recirculation wake decreases with decreasing power-law index, and/or with decreasing bubble aspect ratio, and/or with decreasing Reynolds number. For bubbles of aspect ratio e > 1, a crossover Reynolds number is observed with respect to the power-law index, i.e. below the crossover Reynolds number, the drag coefficient of bubble increases with decreasing power-law index; whereas, above the crossover Reynolds number, a reverse trend is observed. Finally, based on the present numerical results, a simple predictive correlation is proposed for the total drag coefficients of spheroid bubbles rising in Newtonian and power law liquids, which can be used in new applications.