Numerical study on micromixers with smart-rhombic structure

2018 ◽  
Vol 32 (27) ◽  
pp. 1850301 ◽  
Author(s):  
Jiajia Xu ◽  
Xueye Chen ◽  
Yanlin Liu ◽  
Zhen Yao
Keyword(s):  
Numerical Simulation ◽  
High Throughput ◽  
Numerical Study ◽  
Considerable Effect ◽  
Geometric Parameters ◽  
Channel Width ◽  
Variable Method ◽  
Mixing Efficiency ◽  
Width Ratio ◽  
Chaotic Convection

In this paper, we have designed a rhombic microchannel plane micromixer (RMPM). The RMPM uses the principle of converging and diverging to improve the mixing efficiency. We improved the mixing efficiency by changing the rhombic angles and the rhombic channel width ratios. The influence of geometric parameters on mixing efficiency is analyzed by control of the variable method. Through the analysis of the numerical simulation, the RMPM can help increase the chaotic convection between different concentrations of fluids. The results of the study show that the rhombic angle and the width ratio of a microchannel can have a considerable effect on the mixing efficiency. The micromixer can be potentially useful in the future applications of rapid and high throughput mixing.

A NOVEL 3D MICROMIXER WITH QUARTIC KOCH CURVE FRACTAL

2021 ◽  
pp. 2150049
Author(s):  
SIYUE XIONG ◽  
XUEYE CHEN
Keyword(s):  
Numerical Simulation ◽  
Deflection Angle ◽  
Reynolds Numbers ◽  
Mixing Efficiency ◽  
Flow State ◽  
Koch Curve ◽  
Mixing Performance ◽  
Chaotic Convection ◽  
The Deflection Angle ◽  
High Application

In this paper, we mainly study the mixing performance of the micromixer with quartic Koch curve fractal (MQKCF) by numerical simulation. Changing the structure of the microchannel based on the fractal principle can significantly improve the fluid flow state in the microchannel and improve the mixing efficiency of the micromixer. This paper discussed the effects of different fractal deflection angles, microchannel heights and different fractal times on the mixing efficiency under four different Reynolds numbers (Re). It is found that changing the deflection angle of the fractal can bring extremely high benefits, which makes the fluid deflect and fold in the microchannel, enhancing the chaotic convection in the microchannel, and improve the mixing efficiency of the fluid. Under the reasonable arrangement of the quartic Koch curve fractal principle, it can give the micro-mixture more than 99% mixing efficiency. Based on the excellent mixing performance of MQKCF, it also has extremely high application value in the biochemical neighborhood.

scholarly journals Uncertainty Analysis of Mixing Efficiency Variation in Passive Micromixers due to Geometric Tolerances

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Irina Stanciu
Keyword(s):  
Simulation Model ◽  
Numerical Study ◽  
Geometric Parameters ◽  
Mixing Efficiency ◽  
Mixing Performance ◽  
Probabilistic Simulation ◽  
Geometric Tolerances ◽  
The Monte Carlo Method ◽  
Key Factor ◽  
Geometric Layout

The geometric layout is the key factor for enhancing the efficiency of the fluid mixing in passive micromixers. Therefore, by adjusting the geometric design and by controlling the geometric parameters, one can enhance the mixing process. However, through any fabrication process, the geometric parameters present slight, inherent variation from the designed values than might affect the performance of the micromixer. This paper proposes a numerical study on the influence of the unavoidable geometric tolerances on the mixing efficiency in passive micromixers. A probabilistic simulation model, based on the Monte Carlo method, is developed and implemented for this purpose. An uncertainty simulation model shows that significant deviations from the deterministic design can appear due to small variations in the geometric parameters values and demonstrates how a more realistic mixing performance can be estimated.

Numerical simulation of three-dimensional passive micromixer based on the principle of Koch fractal

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Siyue Xiong ◽  
Xueye Chen
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Cross Section ◽  
Three Dimensional ◽  
Mixing Efficiency ◽  
Mixing Performance ◽  
Chaotic Convection ◽  
Passive Micromixer ◽  
Koch Fractal ◽  
Koch Fractal Principle

Abstract In this paper, We arrange the obstacles based on the Koch fractal principle (OKF) in the micromixer. By changing the fluid flow and folding the fluid, a better mixing performance is achieved. We improve the mixing efficiency by placing OKF and changing the position of OKF, then we studied the influence of the number of OKF and the height of the micromixer on the mixing performance. The results show that when eight OKF are staggered in the microchannel and the height is 0.2 mm, the mixing efficiency of the OKF micromixer can reach 97.1%. Finally, we compared the velocity cross section and velocity streamline of the fluid, and analyzed the influence of OKF on the concentration trend. Through analysis, it is concluded that OKF can generate chaotic convection in the fluid, and enhance the mixing of fluids by generating vortices and folding the fluid. It can effectively improve the mixing efficiency of the micromixer.

Numerical Study on the Cathode Channel Width Ratio for Improving Performance of a Passive Air Cooled PEMFC

2020 ◽  
Vol 23 (1) ◽  
pp. 40-48
Author(s):  
Jaeseung Lee ◽  
Nammin Lee ◽  
Kisung Lim ◽  
Jaeyoo Choi ◽  
Hyunchul Ju
Keyword(s):  
Numerical Study ◽  
Channel Width ◽  
Width Ratio

Design and Optimization of the Gas Channels of a PEMFC Using CFD-Based Simulation

2006 ◽  
Author(s):  
P. C. Sui ◽  
S. Kumar ◽  
N. Djilali
Keyword(s):  
Electrical Conductivity ◽  
Fuel Cell ◽  
Flow Field ◽  
Current Distribution ◽  
Geometric Parameters ◽  
Cell Performance ◽  
Channel Width ◽  
Width Ratio ◽  
Land Area ◽  
Land Width

The flow field plate of a proton exchange membrane fuel cell (PEMFC) functions as electron conductor and provides the pathway for oxidant and fuel to reach the membrane electrode assembly (MEA). CFD-based simulation tools can be effective in designing and optimization of flow field plates as they cab fully account for the complexity and coupling of various transport phenomena as well as the 3-D geometry. The objective of this paper is to report on the development of such a simulation platform and on its application to investigate the impact of several geometric parameters on fuel cell performance and detailed distribution of transport processes. The simulation tool is built upon a commercial computational fluid dynamics (CFD) code, CFD-ACE+, along with supporting software and script codes to automate the design workflow. A 3-D, straight channel model with material properties and model parameters validated with experimental data is used as the baseline for the present study. The workflow includes automated grid generation, model setup and job execution. Parametric study is performed for geometric parameters including (1) Channel width versus land area width (2) Channel height (3) Channel pitch and length, as well as material parameters including (4) Porosity and (5) Electrical conductivity of the gas diffusion layer (GDL). Among these parameters, it is found that predicted cell performance is most sensitive to the channel/land width ratio and to the anisotropy of the GDL property. When isotropic properties are used for the GDL, the predicted cell performance decreases with increasing channel/land width ratio. This is because the current distribution in the MEA is dictated by electrical conduction through the GDL and increasing channel width causes current to peak underneath the land area, which in turn increases ohmic losses. When the in-plane electrical conductivity is reduced, the effect of mass transfer on the current distribution becomes comparable to electron transfer and the predicted trend line of cell performance shows an optimum value as a function of the channel/land width ratio. The CFD based design tool developed in the present work has the advantage of providing more reliable prediction than methods based on reduced dimensionality or simplified transport models.

NUMERICAL STUDY ON KOCH FRACTAL BAFFLE MICROMIXER

Fractals ◽  
2019 ◽  
Vol 27 (03) ◽  
pp. 1950026 ◽  
Author(s):  
SHUAI ZHANG ◽  
XUEYE CHEN ◽  
ZHONGLI WU ◽  
YUE ZHENG
Keyword(s):  
Numerical Study ◽  
Mixing Efficiency ◽  
Chaotic Convection ◽  
Koch Fractal ◽  
Better Than

This paper is mainly to study the application of Koch fractal baffle to passive micromixers. It can be determined that the mixing efficiency of secondary Koch fractal baffle (SKFB) micromixer is better than that of primary Koch fractal baffle (PKFB). We compare and analyze the mixing efficiency when the angle between the baffle and the microchannel is [Formula: see text], [Formula: see text] and [Formula: see text] with the height 100[Formula: see text][Formula: see text]m. With the changing of the angle, it contributes to enhance the chaotic convection of the micromixer. Especially at the angle of [Formula: see text], the vortex caused by the Koch fractal baffle structure is more obvious, the mixing efficiency of micromixer is more than 95% at Re [Formula: see text] 0.05 and 100. When the height of Koch fractal baffle is 50, 75 and [Formula: see text]m, the mixing efficiency of the micromixer gradually increases. The whirling and spiral phenomenon of the streamlines increases the chaotic convection and promotes the improvement of the mixing efficiency. In the direction of microchannel, nine sections which have a significant effect on the mixing efficiency are investigated. The encircling and split phenomenon affected by the chaotic convection is shown in nine sections at Re [Formula: see text] 0.05, 10 and 100.

NUMERICAL SIMULATION OF THREE-DIMENSIONAL PASSIVE MICROMIXER WITH VARIABLE-ANGLE GROOVES AND BAFFLES

2021 ◽  
pp. 2150037
Author(s):  
SIYUE XIONG ◽  
XUEYE CHEN
Keyword(s):  
Fluid Flow ◽  
Three Dimensional ◽  
Geometric Parameters ◽  
Mixing Efficiency ◽  
Flow State ◽  
Number Range ◽  
Variable Angle ◽  
Structure Changes ◽  
Chaotic Convection ◽  
Passive Micromixer

In this paper, we have studied the effect of variable-angle grooves and baffles on the mixing efficiency of the micromixer. In order to explore the influence on the micromixer with different types of grooves and baffles, we designed grooves and baffles with different geometric parameters and placed them in T-channels to interfere with fluid flow. We studied VAM30∘ (variable-angle grooves and baffles micromixer with an angle of 30∘) directions and distributions as well as their different groove depths and baffle heights affect the mixing performance. We tried to divide the grooves and baffles into five groups, and discussed the effects of staggered depth and height on mixing efficiency. The mixing efficiencies of micromixer in the Re (Reynolds number) range of 0.1–100 were calculated, and the fluid flow in the microchannel was analyzed. The simulation results show that VAM30∘ is more favorable for solution mixing. The mixing efficiency of the micromixer could reach 98.9% with the change of different geometric parameters. This is because when the structure changes, the flow state of the fluid is improved, which is conducive to lengthening the residence time of the fluid in the channel. With the increase of Re, it is also conducive to enhancing the chaotic convection and improving the mixing efficiency.

Evaluation of an improvement in runoff control by means of a construction of an infiltration sewer pipe under a porous asphalt pavement

1997 ◽  
Vol 36 (8-9) ◽  
pp. 397-402
Author(s):  
Yasuhiko Wada ◽  
Hiroyuki Miura ◽  
Rituo Tada ◽  
Yasuo Kodaka
Keyword(s):  
Numerical Simulation ◽  
Simulation Model ◽  
Asphalt Pavement ◽  
Considerable Effect ◽  
Rainfall Infiltration ◽  
Sewer Pipe ◽  
Porous Asphalt ◽  
Runoff Control

We examined the possibility of improved runoff control in a porous asphalt pavement by installing beneath it an infiltration pipe with a numerical simulation model that can simulate rainfall infiltration and runoff at the porous asphalt pavement. From the results of simulations about runoff and infiltration at the porous asphalt pavement, it became clear that putting a pipe under the porous asphalt pavement had considerable effect, especially during the latter part of the rainfall.

Sign in / Sign up

Export Citation Format

Share Document