Numerical investigation on the influence of surface tension and viscous force on the bubble dynamics with a CLSVOF method

2016 ◽  
Vol 30 (6) ◽  
pp. 2547-2556 ◽  
Author(s):  
Zhiying Wang ◽  
Yikai Li ◽  
Biao Huang ◽  
Deming Gao
Keyword(s):  
Surface Tension ◽  
Numerical Investigation ◽  
Bubble Dynamics ◽  
Viscous Force

Numerical Investigation of Liquid Parameters Effect on the Oscillation of Cavitation Bubble

2014 ◽  
Vol 568-570 ◽  
pp. 1794-1800
Author(s):  
Xiu Mei Liu ◽  
Bei Bei Li ◽  
Wen Hua Li ◽  
Jie He ◽  
Jian Lu ◽  
...  
Keyword(s):  
Surface Tension ◽  
Cavitation Bubble ◽  
Bubble Dynamics ◽  
Dynamic Performance ◽  
Bubble Radius ◽  
Gas Content ◽  
Viscous Force ◽  
Bubble Collapse ◽  
Hydraulic Systems ◽  
Increasing Temperature

Cavitation is a common harmful phenomenon in hydraulic transmission systems. It not only damages flow continuity and reduces medium physical performance, but also induces vibration and noise. At the same time, the efficiency of a system is reduced due to cavitation, especially dynamic performance are deteriorated. Applying commercial CFD software FLUENT, the cavitation issuing from the orifice was numerically investigated, reducing the harm. The effect of liquid parameters (such as surface tension, gas content, and the temperature) on the oscillation of bubble is studied numerically. The modified Rayleigh-Plesset equations are presented to describe the oscillation of bubble in different liquids. Employing the finite difference calculus, the behavior of a cavitation bubble in liquids with different physics parameters are obtained. Meanwhile, the numerical results are compared with experiment results. It is observed that the viscous force decreases the growth and collapse of a bubble, making it expand or collapse less violently. And the surface-tension forces stave bubble growth progress and speed up bubble collapse process. On the other hand, both the maximum bubble radius and bubble lifetime increase with increasing temperature. These results can provide theory basis for understanding cavitation bubble dynamics in the hydraulic systems.

Droplet Formation Under the Effect of a Flexible Nozzle Plate

2007 ◽  
Author(s):  
S. Sangplung ◽  
J. A. Liburdy
Keyword(s):  
Surface Tension ◽  
Droplet Formation ◽  
Step Function ◽  
Droplet Velocity ◽  
Viscous Force ◽  
Flexible Plate ◽  
Computational Domain ◽  
Cfd Model ◽  
Drop On Demand ◽  
Nozzle Plate

Droplet formation from a flexible nozzle plate driven by a prescribed-waveform excitation of a piezoelectric is numerically investigated using a computational fluid dynamics (CFD) model with the VOF method. The droplet generator with a flexible nozzle plate, which is free to vibrate due to the pressure acting on the plate, is modeled in a CFD computational domain. The CFD analysis includes the fluid-structure interaction between fluid and a flexible plate using large deflection theory. The problem is characterized by the nondimensional variables based on the capillary parameters of time, velocity, and pressure. The CFD model is validated with the experiment results. This study examines the characteristics of the applied waveforms and nozzle plate material properties to change the vibrational characteristics of the nozzle plate. The effect of fluid properties on the droplet formation process is also investigated focusing on surface tension and viscous forces. The mechanism of the droplet formation excited by a drop-on-demand piezoelectric waveform is investigated using a step-function and a pulse waveform. The piezoelectric displacement plays an important role in generating either forward-driven momentum or a suction pressure inside the chamber. For the step-function waveform, the nondimensional applied impulse is defined and used to characterize the post-breakoff droplet volume. Increasing the impulse of the piezoelectric can be used to cause a faster droplet velocity and it is shown that the vibration of the nozzle plate has a strong effect on the droplet velocity, shape, and volume. Surface tension has strong influence to the droplet formation characteristics which is contrast to a viscous force that makes no difference on the droplet formation for different viscosities. For the combination of a fluid with high surface tension and the most flexible nozzle plate, this system can not cause the droplet ejected out of the nozzle.

scholarly journals Numerical investigation of bubble dynamics at a corner

2020 ◽  
Vol 32 (5) ◽  
pp. 053306 ◽  
Author(s):  
Mehdi Mahmud ◽  
Warren R. Smith ◽  
A. D. Walmsley
Keyword(s):  
Numerical Investigation ◽  
Bubble Dynamics

scholarly journals Squeezing Dynamic Mechanism of High-Viscosity Droplet and its Application for Adhesive Dispensing in Sub-Nanoliter Resolution

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 728
Author(s):  
Ping Zhu ◽  
Zheng Xu ◽  
Xiaoyu Xu ◽  
Dazhi Wang ◽  
Xiaodong Wang ◽  
...  
Keyword(s):  
Surface Tension ◽  
Contact Force ◽  
Surface Tension Force ◽  
High Viscosity ◽  
Dynamic Mechanism ◽  
Tension Force ◽  
Viscous Force ◽  
Transfer Printing ◽  
Critical Contact ◽  
Printing Method

The dispensing resolution of high-viscosity liquid is essential for adhesive micro-bonding. In comparison with the injection technique, the transfer printing method appears to be promising. Herein, an analytical model was developed to describe the dynamic mechanism of squeezing-and-deforming a viscous droplet between plates in a transfer printing process: as the distance between plates decreases, the main constituents of contact force between the droplet and substrate can be divided into three stages: surface tension force, surface tension force and viscous force, and viscous force. According to the above analysis, the transfer printing method was built up to dispense high-viscosity adhesives, which replaced the geometric parameters, utilized the critical contact force to monitor the adhesive droplet status, and served as the criterion to trigger the liquid-bridge stretching stage. With a home-made device and a simple needle-stamp, the minimum dispensed amount of 0.05 nL (93.93 Pa·s) was achieved. Moreover, both the volume and the contact area of adhesive droplet on the substrate were approximately linear to the critical contact force. The revealed mechanism and proposed method have great potential in micro-assembly and other applications of viscous microfluidics.

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