A novel numerical approach for investigation of the gas bubble characteristics in stagnant liquid using Young-Laplace equation
A novel numerical approach for investigation of the gas bubble characteristics in stagnant liquid using Young-Laplace equation
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DOI：
10.1016/j.ces.2017.07.018
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发表时间：
2017-12-14
影响因子：
4.7
通讯作者：
Ashjaee, Mehdi
中科院分区：
文献类型：
--
作者：
Gharedaghi, Hamed;Dousti, Ahmad;Ashjaee, Mehdi
本文应用Young-Laplace方程模拟了静止液柱中浸没针内气泡的绝热生长过程。为了求解Young-Laplace方程，使用轴对称气泡高度作为来自实验数据的输入。为了提高Young-Laplace方程对气泡生长过程的预测精度，将气泡分为4个高度相同的截面，分别求解每一截面的Young-Laplace方程。通过将气泡分为四个部分，与浮力和液-气表面张力相比，每个部分内的粘性和惯性力的影响被减小。与传统的杨-拉普拉斯方法（一个杨-拉普拉斯方程的整个气泡），新的方法是能够可靠地预测气泡的特性在生长周期。研究了在具有固定于针周边的三重接触线的液柱中气泡的生长。为了验证数值模拟结果，将数值模拟预测的气泡分布与实验结果进行了比较。通过在静态去离子水和SiO2纳米流体中以600 ml/h的恒定气体流速注入空气来进行实验。纳米颗粒浓度为0.05、0.1和0.2重量%，并且空气流从G14和G17标准针注入。最后，对气泡的体积、重心、瞬时接触角、长径比等气泡特性进行了评价，并讨论了液体性质变化对气泡特性的影响。结果表明，该方法可以在97.5%的生长时间内预测气泡形状，平均绝对误差为6%。随着Bond数的增加，气泡尺寸减小.气泡的瞬时接触角和长径比与生长周期中的Bond数几乎无关。(C)2017爱思唯尔有限公司版权所有。
In the present study, the Young-Laplace equation was applied to simulate the adiabatic gas bubble growth from a submerged needle in stagnant liquid column. In order to solve the Young-Laplace equation the axisymmetric bubble height was used as input from experimental data. To increase the accuracy of Young-Laplace equations' prediction during the bubble growth, the bubble was divided into four sections with the same height, and Young-Laplace equation was solved for each section individually. By dividing the bubble into four sections, the effects of viscosity and inertia forces within each section were reduced as compared to that of buoyancy and liquid-gas surface tension. Unlike the conventional Young-Laplace approach (one Young-Laplace equation for the entire bubble), the new approach was able to predict bubble characteristics reliably during the growth cycle. The bubble growth was investigated in a column of liquid with a triple contact line that fixed to the needle perimeter. To validate the numerical results, the bubble profiles that predicted by numerical simulation were compared with the experimental results. Experiments were performed by injection of air at constant gas flow rate of 600 ml/h in the quiescent deionized water and SiO2 nanofluid. The nanoparticle concentrations were 0.05, 0.1 and 0.2 wt%, and air flow injected from G14 and G17 standard needles. Eventually, evaluation of bubble characteristics, such as the bubble volume, the center of gravity, the instantaneous contact angle, and the bubble aspect ratio were investigated, and the effects of variation of liquid properties on the bubble characteristics were discussed. The results show that the present method can predict the bubble shape during 97.5% of growth time with mean absolute error of 6%. Furthermore, the results revealed that the bubble size decreased with increment of Bond number. Also, bubble instantaneous contact angle and bubble aspect ratio were almost irrelative to Bond number during the growth cycle. (C) 2017 Elsevier Ltd. All rights reserved.