• Title/Summary/Keyword: Terminal rise velocity

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Model setup and optimization of the terminal rise velocity of microbubbles using polynomial regression analysis (다항식 회귀분석을 이용한 마이크로 버블의 종말상승속도 모델식 구축 및 운전조건 최적화)

  • Park, Gun-Il;Kim, Heung-Rae;Cho, Il Hyoung
    • Journal of the Korean Applied Science and Technology
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    • v.35 no.4
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    • pp.1393-1406
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    • 2018
  • In this study, three parameters (Pressure ($X_1$), Airflow rate ($X_2$), Operation time ($X_3$)) were experimentally designed and the predicted model and optimal conditions were established by using the terminal rise velocity of the microbubbles as the response value. The polynomial regression analysis showed that the optimum value for the terminal rise velocity at the Pressure ($X_1$) of 4.5 bar, Airflow rate ($X_2$) of 3.3 L/min and Operation time ($X_3$) of 2.2 min was 5.14 cm/min ($85.7{\mu}m/sec$). Also, the highest microbubble diameter size distribution in the range of 2 to $5{\mu}m$ and 25 to $50{\mu}m$ was confirmed by using a laser particle counting apparatus.

THEORETICAL STUDY OF MOTION OF SMALL SPHERICAL AIR BUBBLES IN A UNIFORM SHEAR FLOW OF WATER

  • MEHDI, SYED MURTUZA;KIM, SIN
    • Nuclear Engineering and Technology
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    • v.47 no.1
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    • pp.126-134
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    • 2015
  • A simple Couette flow velocity profile with an appropriate correlation for the free terminal rise velocity of a single bubble in a quiescent liquid can produce reliable results for the trajectories of small spherical air bubbles in a low-viscosity liquid (water) provided the liquid remains under uniform shear flow. Comparison of the model adopted in this paper with published results has been accomplished. Based on this study it has also been found that the lift coefficient in water is higher than its typical value in a high-viscosity liquid and therefore a modified correlation for the lift coefficient in a uniform shear flow of water within the regime of the $E\ddot{o}tv\ddot{o}s$ number $0.305{\leq}Eo{\leq}1.22$ is also presented.

Two-dimensional Numerical Simulation of the Rising Bubble Flows Using the Two Phase Lattice Boltzmann Method (2상 격자 볼츠만 방법을 이용한 상승하는 기포 유동 2차원 수치 모사)

  • Ryu, Seung-Yeob;Park, Cheon-Tae;Han, Seung-Yeul;Ko, Sung-Ho
    • The KSFM Journal of Fluid Machinery
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    • v.13 no.4
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    • pp.31-36
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    • 2010
  • Free energy based lattice Boltzmann method (LBM) has been used to simulate the rising bubble flows with large density ratio. LBM with compact discretization is able to reduce the spurious current of the static bubble test and be satisfied with the Laplace law. The terminal rise velocity and shape of the bubbles are dependent on Eotvos number, Morton number and Reynolds number. For single bubble flows, simulations are executed for various Eotvos number, Morton number and Reynolds number, and the results are agreed well with the experiments. For multiple bubbles, the bubble flow characteristics are related by the vortex pattern of the leading bubble. The coalescence of the bubbles are simulated successfully and the subsequent results are presented. The present method is validated for static, dynamic bubble test cases and compared to the numerical, experimental results.