3D simulations have been achieved on a flow‐focusing geometry employing the VOF method to study the consequence of viscosity, surface tension, wettability, and geometry on drop generation for the dripping regime. Here the dispersed phase is the PDMS oil (polydimethylsiloxane), and the continuous phase is the water. Simulations were performed at different oil‐to‐water viscosity ratios of 3, 12, 27, and 50. The interfacial tension between PDMS oil and water is 0.0118 N/m. It has been abridged to 0.008 N/m, 0.005 N/m, and 0.002 N/m, and simulations were performed. The walls of the microchannel are considered to be PMMA surfaces. The contact angle of an oil droplet on the PMMA surface in the presence of water is 140°. The effect of wettability was shown at various contact angles (angle created by water droplet on the PMMA surface in the presence of oil) of 0°, 40°, 90°, 135° and 180°. The frequency of droplet generation (1/s), non‐dimensional droplet length (L/Wc), droplet volume (nl), and droplet velocity (m/s) have been calculated for each of the cases. A flow pattern map has been industrialized classifying the dripping and jetting regimes. A comparison between normal geometry and two constricted geometries (having different orifice lengths) based on the frequency of droplet, non‐dimensional drop length, drop volume, and drop velocity has been made for both dripping and jetting regimes. Prediction of simulated non‐dimensional droplet length has also been made using dimensional analysis.

中文翻译：

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流聚焦几何中滴水和喷射现象的三维模拟

使用 VOF 方法对流聚焦几何结构进行了 3D 模拟，以研究粘度、表面张力、润湿性和几何形状对滴注状态下液滴生成的影响。这里的分散相是PDMS油（聚二甲基硅氧烷），连续相是水。在不同的油水粘度比 3、12、27 和 50 下进行模拟。PDMS 油和水之间的界面张力为 0.0118 N/m。已简化为0.008 N/m、0.005 N/m、0.002 N/m，并进行了模拟。微通道的壁被认为是PMMA表面。在有水存在的情况下，油滴在 PMMA 表面上的接触角为 140°。润湿性的影响在 0°、40°、90°、135° 和 180° 的各种接触角（有油的情况下水滴在 PMMA 表面上形成的角度）下显示。液滴生成频率（1/s）、无量纲液滴长度（L/WC）、液滴体积（nl）和液滴速度（m/s）已针对每种情况进行了计算。流型图已经工业化，对滴水和喷射状态进行分类。基于液滴频率、无量纲液滴长度、液滴体积和液滴速度，对滴注和喷射状态下的正常几何形状和两种收缩几何形状（具有不同的孔口长度）进行了比较。还使用量纲分析对模拟的无量纲液滴长度进行了预测。