A Study on Characteristics of Fluid Flow and Mixing in a Microchannel With a Controlled Local Electric Field

2006 ◽  
Author(s):  
Hyeung Seok Heo ◽  
Yong Kweon Suh ◽  
Sang Mo Kang
Keyword(s):  
Fluid Flow ◽  
Electric Field ◽  
Three Dimensional ◽  
Metal Electrode ◽  
Rotational Flow ◽  
Metal Electrodes ◽  
Mixing Index ◽  
Mixing Effect ◽  
Commercial Code ◽  
Parameter Values

In this study a newly designed microchannel is proposed. This design is comprised of a channel and a series of metal electrodes periodically attached on the both side’s surfaces of the channel. In this configuration, the mixing effect is greatly enhanced at a certain parameter values. To characterize the flow field and the mixing effect, both numerical and experimental methods were employed. To obtain the potential field, electric field, and velocity vectors three-dimensional numerical computation was performed by using a commercial code, CFD-ACE+. The fluid-flow solutions were then cast into studying the characteristics of stirring with the aid of mixing index. In this study the mixing index were computed manually because the commercial code does not provide the corresponding tool. In the experiment, flow visualization was performed by using water with fluorescent particles. The numerical results show that the velocity pattern in the microchannel heavily depends on the metal electrodes arrangement on both sides. It was shown that the rotational flow is significantly enhanced by a higher voltage of metal electrode.

Numerical Simulations of Heat Transfer and Fluid Flow for a Rotating High-Pressure Turbine

2006 ◽  
Author(s):  
F. Mumic ◽  
L. Ljungkruna ◽  
B. Sunden
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Fluid Flow ◽  
Numerical Study ◽  
Three Dimensional ◽  
Turbulence Models ◽  
High Pressure Turbine ◽  
Experimental Heat ◽  
Commercial Code ◽  
Stator Vane

In this work, a numerical study has been performed to simulate the heat transfer and fluid flow in a transonic high-pressure turbine stator vane passage. Four turbulence models (the Spalart-Allmaras model, the low-Reynolds-number realizable k-ε model, the shear-stress transport (SST) k-ω model and the v2-f model) are used in order to assess the capability of the models to predict the heat transfer and pressure distributions. The simulations are performed using the FLUENT commercial software package, but also two other codes, the in-house code VolSol and the commercial code CFX are used for comparison with FLUENT results. The results of the three-dimensional simulations are compared with experimental heat transfer and aerodynamic results available for the so-called MT1 turbine stage. It is observed that the predictions of the vane pressure field agree well with experimental data, and that the pressure distribution along the profile is not strongly affected by choice of turbulence model. It is also shown that the v2-f model yields the best agreement with the measurements. None of the tested models are able to predict transition correctly.

Numerical Simulation of Fluid Flow in a New High Efficient Mixer

2012 ◽  
Vol 251 ◽  
pp. 226-230
Author(s):  
Qing Wu ◽  
Ya Chen Zhang ◽  
Xue Jun Liu ◽  
Bao An Han
Keyword(s):  
Fluid Flow ◽  
Flow Direction ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Computational Results ◽  
Static Mixer ◽  
Turbulent Model ◽  
Mixing Effect ◽  
High Efficient ◽  
Processing Software

In order to determine proper structural parameters of the new high efficient mixer created by the author, the CFD software is applied to simulate numerically three dimensional incompressible turbulent fields for three static mixing units and the mixing unit with rotating impellor. The static mixing units include three kinds of spiral blades that are single-blade style, three-blade style and four-blade style. Geometric models are built by Pro/ENGINEER and exported to Fluent. The time-mean Reynolds equations and standard turbulent model are applied, and the post-processing software is used to analyze the computational results, and velocity contours and stress contours of mixing fluids in the static mixer will be obtained. The computational results indicate that the direction of outlet velocity of three-blade fluid flow turns more dramatically in comparison with that of single-blade and four-blade fluid flow, and the shearing stress is more remarkable. Because the internal stress of three-blade fluid changes more, the mixing action among fluids is more intensified. All these show three-blade spiral blades have the best mixing effects for local fluids. The rotating impellor mounted between blades can change fluid flow direction and improve the mixing effect for local fluids, which is moved by fluid flow with some velocity.

The Effect of Roughness Features on Mos Surface Electric Field and Fowler-Nordheim Tunneling Behavior

1997 ◽  
Vol 473 ◽  
Author(s):  
Heng-Chih Lin ◽  
Edwin C. Kan ◽  
Toshiaki Yamanaka ◽  
Simon J. Fang ◽  
Kwame N. Eason ◽  
...  
Keyword(s):  
Electric Field ◽  
Three Dimensional ◽  
Tunneling Current ◽  
Gate Oxide ◽  
Oxide Thickness ◽  
Interface Roughness ◽  
Normal Electric Field ◽  
Surface Electric Field ◽  
Tunneling Behavior ◽  
Nordheim Tunneling

ABSTRACTFor future CMOS GSI technology, Si/SiO2 interface micro-roughness becomes a non-negligible problem. Interface roughness causes fluctuations of the surface normal electric field, which, in turn, change the gate oxide Fowler-Nordheim tunneling behavior. In this research, we used a simple two-spheres model and a three-dimensional Laplace solver to simulate the electric field and the tunneling current in the oxide region. Our results show that both quantities are strong functions of roughness spatial wavelength, associated amplitude, and oxide thickness. We found that RMS roughness itself cannot fully characterize surface roughness and that roughness has a larger effect for thicker oxide in terms of surface electric field and tunneling behavior.

Effect of external magnetic field on lane formation in driven pair-ion plasmas

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Swati Baruah ◽  
U. Sarma ◽  
R. Ganesh
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Coupling Parameter ◽  
Critical Parameters ◽  
Coulomb Coupling ◽  
Lane Formation ◽  
Parameter Values

Lane formation dynamics in externally driven pair-ion plasma (PIP) particles is studied in the presence of external magnetic field using Langevin dynamics (LD) simulation. The phase diagram obtained distinguishing the no-lane and lane states is systematically determined from a study of various Coulomb coupling parameter values. A peculiar lane formation-disintegration parameter space is identified; lane formation area extended to a wide range of Coulomb coupling parameter values is observed before disappearing to a mixed phase. The different phases are identified by calculating the order parameter. This and the critical parameters are calculated directly from LD simulation. The critical electric field strength value above which the lanes are formed distinctly is obtained, and it is observed that in the presence of the external magnetic field, the PIP system requires a higher value of the electric field strength to enter into the lane formation state than that in the absence of the magnetic field. We further find out the critical value of electric field frequency beyond which the system exhibits a transition back to the disordered state and this critical frequency is found as an increasing function of the electric field strength in the presence of an external magnetic field. The movement of the lanes is also observed in a direction perpendicular to that of the applied electric and magnetic field directions, which reveals the existence of the electric field drift in the system under study. We also use an oblique force field as the external driving force, both in the presence and absence of the external magnetic field. The application of this oblique force changes the orientation of the lane structures for different applied oblique angle values.

scholarly journals Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1622
Author(s):  
Wipawee Tepnatim ◽  
Witchuda Daud ◽  
Pitiya Kamonpatana
Keyword(s):  
Temperature Distribution ◽  
Electric Field ◽  
Three Dimensional ◽  
Development Stage ◽  
Microwave Oven ◽  
Computational Time ◽  
Plastic Package ◽  
Heating Uniformity ◽  
The Cost ◽  
Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

scholarly journals Fast multipole solvers for three-dimensional radiation and fluid flow problems

1999 ◽  
Vol 7 ◽  
pp. 408-417 ◽  
Author(s):  
J. H. Strickland ◽  
L. A. Gritzo ◽  
R. S. Baty ◽  
G. F. Homicz ◽  
S. P. Burns
Keyword(s):  
Fluid Flow ◽  
Three Dimensional ◽  
Fast Multipole ◽  
Flow Problems
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