Fluid mixing in droplet-based microfluidics with a serpentine microchannel

RSC Advances ◽  
2015 ◽  
Vol 5 (126) ◽  
pp. 104138-104144 ◽  
Author(s):  
Jiajun Wang ◽  
Jianan Wang ◽  
Lianfang Feng ◽  
Tong Lin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Volume Of Fluid ◽  
Fluid Mixing ◽  
Dynamics Simulation ◽  
Mixing Process ◽  
Computational Fluid Dynamics Simulation ◽  
Simulation Based

The hydrodynamics and mixing process within droplets travelling along a three dimensional serpentine microchannel have been studied using a computational fluid dynamics simulation based on the volume-of-fluid approach.

Experimental and simulation study of thermal accumulation in an enclosed vehicle

2019 ◽  
Vol 233 (14) ◽  
pp. 3621-3629
Author(s):  
Sing Ngie David Chua ◽  
Boon Kean Chan ◽  
Soh Fong Lim
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Dynamics Simulation ◽  
Computational Fluid Dynamics Simulation ◽  
Heat Accumulation ◽  
Ansys Fluent ◽  
Direct Exposure ◽  
Car Park

Thermal accumulation in a car cabin under direct exposure to sunlight can be extremely critical due to the risk of heatstroke especially to children who are left unattended in the car. There are very limited studies in the literature to understand the thermal behaviour of a car that is parked in an open car park space and the findings are mostly inconsistent among researchers. In this paper, the studies of thermal accumulation in an enclosed vehicle by experimental and computational fluid dynamics simulation approaches were carried out. An effective and economical method to reduce the heat accumulation was proposed. Different test conditions such as fully enclosed, fully enclosed with sunshade on front windshield and different combinations of window gap sizes were experimented and presented. Eight points of measurement were recorded at different locations in the car cabin and the results were used as the boundary conditions for the three-dimensional computational fluid dynamics simulation. The computational fluid dynamics software used was ANSYS FLUENT 16.0. The results showed that the application of sunshade helped to reduce thermal accumulation at car cabin by 11.5%. The optimum combination of windows gap size was found to be with 4-cm gap on all four windows which contributed to a 21.1% reduction in car cabin temperature. The results obtained from the simulations were comparable and in agreement with the experimental tests.

Three-dimensional computational fluid dynamics simulation of valve-induced water hammer

2016 ◽  
Vol 231 (12) ◽  
pp. 2263-2274 ◽  
Author(s):  
Shuai Yang ◽  
Dazhuan Wu ◽  
Zhounian Lai ◽  
Tao Du
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Method Of Characteristics ◽  
Three Dimensional ◽  
Water Hammer ◽  
Dynamics Simulation ◽  
Computational Fluid Dynamics Simulation ◽  
Time Step ◽  
Obvious Effect ◽  
Simulation Results

In this study, three-dimensional computational fluid dynamics simulation was adopted to evaluate the valve-induced water hammer phenomena in a typical tank-pipeline-valve-tank system. Meanwhile, one-dimensional analysis based on method of characteristics was also used for comparison and reference. As for the computational fluid dynamics model, the water hammer event was successfully simulated by using the sliding mesh technology and considering water compressibility. The key factors affecting simulation results were investigated in detail. It is found that the size of time step has an obvious effect on the attenuation of the wave and there exists a best time step. The obtained simulation results have a good agreement with the experimental data, which shows an unquestionable advantage over the method of characteristics calculation in predicting valve-induced water hammer. In addition, the computational fluid dynamics simulation can also provide a visualization of the pressure and flow evolutions during the transient process.

Fluid Mixing in Channels With Microridges

2007 ◽  
Author(s):  
Zheng Xia ◽  
Lou Cattafesta ◽  
Mark Sheplak ◽  
Renwei Mei ◽  
Z. Hugh Fan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fluid Flow ◽  
Cross Section ◽  
Fluorescence Intensity ◽  
Flow Behavior ◽  
Fluid Mixing ◽  
Dynamics Simulation ◽  
Uneven Surface ◽  
Computational Fluid Dynamics Simulation

Microflows in complex channels with uneven surface often display unusual flow behavior compared to their macroscale counterparts. Channels with micro ridges are created in a plastic device using photolithography and molding. Recirculation is reported in the flow in these ridged channels [1]. We use recirculation to enhance fluid mixing and the utility is demonstrated by homogenizing fluorescein and water in the microchannels. In addition, deconvolution microscopy is developed to visualize the fluid flow in the ridged channel. Flow twisting, as expected, results in enhanced fluid mixing; the fluorescence intensity at a cross section is calculated as an indicator of the degree of mixing. The preliminary results show rapid mixing in the ridged channels, verifying existence of circulation. We also compared the experimental results with that from computational fluid dynamics simulation.

scholarly journals A computational fluid dynamics simulation of liquid swallowing by impaired pharyngeal motion: bolus pathway and pharyngeal residue

2019 ◽  
Vol 317 (6) ◽  
pp. G784-G792 ◽  
Author(s):  
Jun Ohta ◽  
Shunichi Ishida ◽  
Tetsuaki Kawase ◽  
Yukio Katori ◽  
Yohsuke Imai
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Dynamics Simulation ◽  
Residual Volume ◽  
Computational Fluid Dynamics Simulation ◽  
Pharyngeal Residue ◽  
Computational Modeling And Simulation ◽  
Liquid Bolus ◽  
Thickening Agents

Common practices to improve the ability to swallow include modifying physical properties of foods and changing the posture of patients. Here, we quantified the effects of the viscosity of a liquid bolus and patient posture on the bolus pathway and pharyngeal residue using a computational fluid dynamics simulation. We developed a computational model of an impaired pharyngeal motion with a low pharyngeal pressure and no pharyngeal adaptation. We varied viscosities from 0.002 to 1 Pa·s and postures from −15° to 30° (from nearly vertical to forward leaning). In the absence of pharyngeal adaptation, a honey-like liquid bolus caused pharyngeal residue, particularly in the case of forward-leaning postures. Although the bolus speed was different among viscosities, the final pathway was only slightly different. The shape, location, and tilting of the epiglottis effectively invited a bolus to two lateral pathways, suggesting a high robustness of the swallowing process. NEW & NOTEWORTHY Thickening agents are often used for patients with dysphagia. An increase in bolus viscosity not only reduces the risk of aspiration but also can cause a residual volume in the pharynx. Because information obtained from videofluoroscopic swallowing studies is only two-dimensional, measurement of pharyngeal residue is experimentally difficult. We successfully quantified the three-dimensional bolus pathway and the pharyngeal residual volume using computational modeling and simulation.

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