Investigation of Three-Dimensional Flow in Microchannels With Patterned Surfaces

2007 ◽  
Author(s):  
Auro Ashish Saha ◽  
Sushanta K. Mitra
Keyword(s):  
Surface Tension ◽  
Flow Instability ◽  
Numerical Study ◽  
Three Dimensional ◽  
Surface Characteristics ◽  
Bottom Wall ◽  
Surface Tension Effect ◽  
Hydrophobic Region ◽  
Side Walls ◽  
Dimensional Simulation

A three-dimensional numerical simulation of flow in patterned microchannel with alternate layers of hydrophilic and hydrophobic surfaces at the bottom wall is studied here. Surface characteristics of the microchannel are accounted by specifying the contact angle and the surface tension of the fluid. Meniscus profiles with varying amplitude and shapes are obtained under the different specified surface conditions. Flow instability increases as the fluid at the bottom wall traverses alternately from hydrophilic region to hydrophobic region. To understand the surface tension effect of the side walls, a two-dimensional numerical study has also been carried out for the microchannel and the results are compared with three-dimensional simulation. The surface tension effect of the side walls enhances the capillary effect for three-dimensional case.

scholarly journals Design and Optimum of Dust Collector with Corrugated Plate for Underground Mine

2018 ◽  
Vol 2018 ◽  
pp. 1-5
Author(s):  
Ming Li ◽  
Chao Wu ◽  
Zhi-yong Zhou ◽  
Wei-chun Lian ◽  
Zhi-xiong Chen
Keyword(s):  
Removal Efficiency ◽  
Three Dimensional ◽  
Surface Characteristics ◽  
Dust Removal ◽  
Dust Collector ◽  
Dust Collection ◽  
Ansys Fluent ◽  
Metal Mine ◽  
Lead Zinc ◽  
Dimensional Simulation

A set of dust collectors was designed with corrugated plate for an underground metal mine, which has low ventilation resistance, simple maintenance, and strong environmental adaptability. A three-dimensional simulation model was built based on ANSYS-Fluent software, and it was used to analyze the influence law of key parameters on the comprehensive dust removal efficiency; the angle of corrugated plate to the horizontal plane, the surface characteristics of plate, pressure loss and dust removal efficiency were discussed. The optimal design scheme of the dust collector was determined according to the simulation results. The dust collection was carried out in the Fankou lead-zinc underground metal mine in China, and the total dust removal efficiency was more than 95%, and for respiratory dust, it was more than 85%. This dust collector can be widely used in similar underground metal mines.

Numerical Anaysis of a Thermopneumatic Micropump

2010 ◽  
Author(s):  
S. Shahsavari ◽  
M. B. Shafii ◽  
M. H. Saidi
Keyword(s):  
Fluid Flow ◽  
Numerical Study ◽  
Three Dimensional ◽  
Working Fluid ◽  
Structure Interaction ◽  
Positive Displacement ◽  
Dimensional Simulation ◽  
Center Deflection ◽  
Bidirectional Flow ◽  
Secondary Fluid

Thermopneumatic micropump is one type of positive displacement micropump, which has many applications due to its relatively large stroke volume, low working voltage, and simple fabrication in microscale. In this paper, a numerical study of heat transfer and fluid flow in a valveless thermopneumatically driven micropump is presented. For rectifying the bidirectional flow, a nozzle and a diffuser are used as the inlet and outlet channels of the chamber. Since the fluid flow is induced by the motion of a diaphragm, the numerical simulation includes fluid structure interaction, which requires applying a dynamic mesh. The domain of solution is divided into two sections; the actuator unit, which contains the secondary fluid, and the main chamber through which the working fluid is passing. The temperature distribution, the pressure variations, and the center deflection of the diaphragm are obtained. In order to validate the model, the numerical results are compared with some experimental data, which shows fair consistency. According to the results of the three dimensional simulation, the rectification efficiency for the nozzle and diffuser channels depends on the frequency.

Numerical Study on Layout of Refractory Belt and Fouling Deposition in Tangentially Fired Boiler

2016 ◽  
Author(s):  
Qiongliang Zha ◽  
Kai Chen ◽  
Jianwen Zhang ◽  
Jiangtao Li ◽  
Chang’an Wang ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Numerical Investigation ◽  
Numerical Study ◽  
High Surface ◽  
Three Dimensional ◽  
Furnace Wall ◽  
Combustion Stability ◽  
Particle Capture ◽  
Dimensional Simulation ◽  
Ignition And Combustion

The refractory belt installed in primary combustion zone provides simplest and most effective solution to suppress ignition delay and enhance combustion stability for low volatile anthracite and lean coal. The fouling deposition generally formed on radiative refractory lined wall of the boiler due to a high surface temperature. The growth of deposition thickness is mainly dependent on the parcile impact on the surface of water wall. A particle capture submodel was used to determine whether a particle was captured to form deposition or not when it reached the furnace wall, and the particle capture criterion was based on the particle’s viscosity and the temperature of the furnace wall. A reduced fouling deposition model was implemented in a three dimensional simulation of a tangentially fired boiler. The numerical investigation was conducted to assess the performance of different layouts of refractory belt. Furnace temperature, surface temperature of refractory belt, and deposition distributions on the furnace wall should be taken into account when layouts of refractory belt are optimized. Based on this, three layouts of refractory belt were proposed for tangentially fired boilers. A numerical investigation was conducted to assess the performance of different layouts of refractory belt and the results showed that the temperature in furnace was increased, and the ignition and combustion processes were stabilized when refractory belts were installed. The reasonable arrangement of refractory belt could reduce the possibility of fouling deposition in furnace.

scholarly journals A Numerical Study of the effect of Bolt Thread Geometry on the Load Distribution of Continuous Threads

2021 ◽  
Author(s):  
Abdulla Sherif Mahmoud Fathalla ◽  
◽  
Ali Akhavan Farid ◽  
Reza Moezzi ◽  
Seyed Saeid Rahimian Koloor ◽  
...  
Keyword(s):  
Load Distribution ◽  
Numerical Study ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Reliable Performance ◽  
Dimensional Simulation ◽  
Three Dimensional Finite Element ◽  
Distribution Behaviour

Load distribution has been studied extensively for ISO thread, but the load distribution on power screw threads, specifically ACME and Square threads, has not been studied yet. In this article, axisymmetric two-dimensional and three-dimensional Finite Element Analysis have been conducted on bolts with different sizes and thread geometries to examine the effect of the thread geometry on the load distribution. The thread geometries were studied with ISO, ACME, and Square threads attention. The sizes used are from the ISO coarse series. In order to investigate on the effect of bolt thread geometry, several simulations have been performed. The two-dimensional simulation results have shown reliable performance in determining the load distribution behaviour when the thread geometry is modified. Moreover, the results agreed with the three-dimensional simulation outcomes regarding the load distribution behaviour when the size is varied.

scholarly journals Numerical study on aerothermal performance of shroud movement in the vivinity of turbine tips

2020 ◽  
pp. 321-321
Author(s):  
Yunsong Zhang ◽  
Yongbao Liu ◽  
Yujie Li ◽  
Qijie Li
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Flow Structure ◽  
Numerical Study ◽  
Three Dimensional ◽  
Breakdown Point ◽  
Axial Direction ◽  
Suction Surface ◽  
Initial Location ◽  
Dimensional Simulation

In this paper, the effects of shroud movement on transonic flow and heat transfer in the vicinity of turbine tip was studied by using three-dimensional simulation of GE-E3 first-stage HPT. Aerothermal performance and flow structure were analyzed with and without turbine shroud moving, respectively. Based on the distribution of limiting streamlines and the vortex structures, the influential characteristics between the leakage flow and the secondary flow generated by shroud movement were studied. Moreover, the coefficient of heat transfer at the wall were investigated. Results show that the flow structure is changing with the movement of turbine shroud, and the location of the separation line changes significantly by the influence of the secondary flow. The leakage vortex initial location delayed in axial direction and its breakdown point located at 65% cross section. This accelerates the mixing loss and increase the perturbation. In addition, it is observed that the coefficient of average heat transfer is increased obviously by 54.8% in the region of shroud surface. However, this coefficient in the region of suction surface decreased by 11.9%.

Nonlinear electroviscoelastic potential flow instability theory of two superposed streaming dielectric fluids

2014 ◽  
Vol 92 (10) ◽  
pp. 1249-1257 ◽  
Author(s):  
M.F. El-Sayed ◽  
N.T. Eldabe ◽  
M.H. Haroun ◽  
D.M. Mostafa
Keyword(s):  
Surface Tension ◽  
Electric Field ◽  
Potential Flow ◽  
Flow Instability ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Physical Parameters ◽  
Two Dimensional ◽  
Dielectric Fluids ◽  
Fluid Velocities

The nonlinear electrohydrodynamic Kelvin–Helmholtz instability of two superposed viscoelastic Walters B′ dielectric fluids in the presence of a tangential electric field is investigated in three dimensions using the potential flow analysis. The method of multiple scales is used to obtain a dispersion relation for the linear problem, and a nonlinear Ginzburg–Landau equation with complex coefficients for the nonlinear problem. The linear and nonlinear stability conditions are obtained and discussed both analytically and numerically. In the linear stability analysis, we found that the fluid velocities and kinematic viscosities have destabilizing effects, and the electric field, kinematic viscoelasticities, and surface tension have stabilizing effects; and that the system in the three-dimensional disturbances is more stable than in the corresponding case of two-dimensional disturbances. While in the nonlinear analysis, for both two- and three-dimensional disturbances, we found that the fluid velocities, surface tension, and kinematic viscosities have destabilizing effects, and the electric field, kinematic viscoelasticities have stabilizing effects, and that the system in the three-dimensional disturbances is more unstable than its behavior in the two-dimensional disturbances for most physical parameters except the kinematic viscosities.

Numerical Study of Large Diameter Butterfly Valve on Flow Characteristics

2011 ◽  
Vol 236-238 ◽  
pp. 1653-1657 ◽  
Author(s):  
Xiao Dong Wang ◽  
Jing Liang Dong ◽  
Tian Wang
Keyword(s):  
Pressure Drop ◽  
Flow Resistance ◽  
Numerical Study ◽  
Large Diameter ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Numerical Approach ◽  
Resistance Coefficient ◽  
Butterfly Valve ◽  
Dimensional Simulation

A numerical approach was used to investigate the flow characteristics around a butterfly valve with the diameter of 2108 mm by the commercial computational fluid dynamics (CFD) code FLUENT6.3. The simulation was carried out to predict flow field structure, flow resistance coefficient, hydrodynamics torque and so on, when the large diameter butterfly valve operated at various opening degrees. The three-dimensional simulation results shown that there are vortexes presented near valve back region as the opening degree smaller than 40 degree; the flow resistance coefficient reduces rapidly with the increasing of opening degree and the resistance coefficient is quite small as the angle larger than 50 degree; the hydrodynamic torque reduces with the increasing of opening degree and the hydrodynamic torque is smaller than 20% of maximum torque; the torque ratio and the pressure drop ratio are reduce with the increasing of opening degree, the pressure drop ratio reduces rapidly as the opening degree is smaller than 50 degree.

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