ORCID Profile
0000-0002-0682-0603
Current Organisation
Tianjin University
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Publisher: IEEE
Date: 02-2011
Publisher: AIP Publishing
Date: 10-2010
DOI: 10.1063/1.3496359
Abstract: In this paper, thermal mixing characteristics of two miscible fluids in a T-shaped microchannel are investigated theoretically, experimentally, and numerically. Thermal mixing processes in a T-shaped microchannel are ided into two zones, consisting of a T-junction and a mixing channel. An analytical two-dimensional model was first built to describe the heat transfer processes in the mixing channel. In the experiments, de-ionized water was employed as the working fluid. Laser induced fluorescence method was used to measure the fluid temperature field in the microchannel. Different combinations of flow rate ratios were studied to investigate the thermal mixing characteristics in the microchannel. At the T-junction, thermal diffusion is found to be dominant in this area due to the striation in the temperature contours. In the mixing channel, heat transfer processes are found to be controlled by thermal diffusion and convection. Measured temperature profiles at the T-junction and mixing channel are compared with analytical model and numerical simulation, respectively.
Publisher: Elsevier BV
Date: 07-2015
Publisher: Elsevier BV
Date: 2012
Publisher: Elsevier BV
Date: 10-2011
Publisher: AIP Publishing
Date: 06-2023
DOI: 10.1063/5.0153676
Abstract: Droplet coalescence is an important process in nature and various technologies (e.g., inkjet printing). Here, we unveil the surfactant mass transport mechanism and report on several major differences in the coalescence of surfactant-laden droplets as compared to pure water droplets by means of molecular dynamics simulation of a coarse-grained model. Large-scale changes to bridge growth dynamics are identified, such as the lack of multiple thermally excited precursors, attenuated collective excitations after contact, slowing down in the inertial regime due to aggregate-induced rigidity and reduced water flow, and a slowing down in the coalescence rate (deceleration) when surfactant concentration increases, while at the same time, we also confirm the existence of an initial thermal, and a power-law, inertial, regime of the bridge growth dynamics in both the pure and the surfactant-laden droplets. Thus, we unveil the key mechanisms in one of the fundamental topological processes of liquid droplets containing surfactant, which is crucial in relevant technologies.
Publisher: Elsevier BV
Date: 02-2013
Publisher: Elsevier BV
Date: 03-2012
Publisher: Elsevier BV
Date: 10-2010
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0LC00917B
Abstract: We present real-time quantitative phase microscopy (RT-QPM) that can be used for on-chip three-dimensional visualization of droplets and high-throughput quantitative molecular measurement via real-time extraction of s le-induced phase variation.
Publisher: AIP Publishing
Date: 09-2022
DOI: 10.1063/5.0101930
Abstract: Atmospheric aerosols can consist of inorganic and organic substances, including surfactants at a significant concentration. Importantly, the latter can reduce the surface tension at the liquid–vapor surfaces, where they preferentially adsorb due to their hiphilic structure. As a result, processes such as droplet coalescence, development of precipitation, and ultimately cloud lifetime may depend on the presence of surfactants in the aerosols. Here, we present a numerical model for cloud droplet formation, which is based on the Lagrangian particle-based microphysics-scheme superdroplet method and takes into account the presence of the surfactant in the droplets. Our results show that surfactant facilitates cloud formation by increasing the number and size of activated droplets, which concentrate at the bottom of the cloud, while the largest droplets are concentrated at the top of the cloud. This indicates a circulation of droplets that involves activation and growth processes from the bottom of the cloud toward the top. Moreover, our conclusions are independent of the particular approach used for modeling the diffusion of Eulerian variables due to the subgrid-scale turbulence. We anticipate that our results will enrich our understanding of the role of surfactants in the behavior of atmospheric aerosols and, importantly, will pave the way for further developments in the numerical modeling of systems with surfactants at macroscopic scales.
Publisher: Elsevier BV
Date: 10-2014
Publisher: AIP Publishing
Date: 07-2023
DOI: 10.1063/5.0157752
Abstract: The breakup of liquid threads into smaller droplets is a fundamental problem in fluid dynamics. In this study, we estimate the characteristic wavelength of the breakup process by means of many-body dissipative particle dynamics. This wavelength shows a power-law dependence on the Ohnesorge number in line with results from stability analysis. We also discover that the number of satellite droplets exhibits a power-law decay with exponent 0.72 ± 0.04 in the product of the Ohnesorge and thermal capillary numbers, while the overall size of main droplets is larger than that based on the characteristic wavelength thanks to the asynchronous breakup of the thread. Finally, we show that the formation of satellite droplets is the result of the advection of pinching points toward the main droplets in a remaining thinning neck, when the velocity gradient of the fluid exhibits two symmetric maxima.
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3SM01046E
Publisher: Elsevier BV
Date: 04-2010
Publisher: Springer Science and Business Media LLC
Date: 2017
Publisher: Elsevier BV
Date: 11-2011
Publisher: AIP Publishing
Date: 31-01-2011
DOI: 10.1063/1.3552680
Abstract: A flow focusing junction is integrated into a microchannel to break up droplets into a controllable number and size of daughter droplets. High speed images of the breakup at the flow focusing junction show that the breakup depends on the interplay between interfacial tension, shear force on the interface, and the confinement of the microchannel. Phase diagrams of the splitting performance show that the breakup is controllable by varying the flow rate of the continuous phase or by varying the size of the mother droplet.
Publisher: American Physical Society (APS)
Date: 12-12-2011
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Zhizhao Che.