A Three Dimensional Simulation Model for Liquid Phase Electroepitaxy Under Magnetic Field

2002 ◽  
Author(s):  
Yoncai Liu ◽  
Hamdi Sheibani ◽  
Susumu Sakai ◽  
Yasunori Okano ◽  
Sadik Dost
Keyword(s):  
Magnetic Field ◽  
Liquid Phase ◽  
Flow Field ◽  
Three Dimensional ◽  
Flow Patterns ◽  
Stable Region ◽  
Transitional Region ◽  
Unstable Flow ◽  
Growth Interface ◽  
Flow Intensity

A three-dimensional numerical simulation for the Liquid Phase Electroepitaxial (LPEE) growth of GaAs under a vertical stationary magnetic field was carried out. The effect of magnetic field intensity on the flow field in the liquid solution was investigated. Numerical results show that the flow patterns exhibit three distinct stability characteristics: a stable flow field up to a magnetic field level of Ha = 150, a transitional flow between Ha = 150 and Ha = 220, and an unstable flow above Ha = 220. In the stable region, the applied magnetic field suppresses the flow field, and the flow intensity decreases with increasing magnetic field. In the transitional region, the flow intensity increases dramatically with increase in the magnetic field strength. The flow patterns are significantly different from those in the stable region. The flow field is no longer axisymmetric but still stable. In the unstable region, the flow structure and intensity change with time. Under a strong magnetic field, the flow cells are confined to the vicinity of the vertical wall and exhibit significant non-uniformity near the growth interface. Such strong flow fluctuations and non-uniformities near the growth interface may have an adverse effect on the growth process and lead to an unsatisfactory growth.

scholarly journals Three Dimensional Effect of Axial Magnetic Field to Suppress Convection in the Solvent of Ge0.98Si0.02 Grown By the Traveling Solvent Method

2021 ◽  
Author(s):  
Leily Abidi
Keyword(s):  
Magnetic Field ◽  
Stokes Equations ◽  
Axial Magnetic Field ◽  
Three Dimensional ◽  
Maximum Velocity ◽  
Navier Stokes ◽  
Growth Interface ◽  
Navier Stokes Equations ◽  
Solvent Method ◽  
Element Technique

A three dimensional numerical simulation of the effect of an axial magnetic field on the fluid flow, heat and mass transfer within the solvent of GE0.98Si0.02 grown by the travelling solvent method is presented. The full steady state Navier-Stokes equations, as well as the energy, continuity and the mass transport equations, were solved numerically using the finite element technique. It is found that a strong convective flow exists in the solvent, which is known to be undesirable to achieve a uniform crystal. An external axial magnetic field is applied to suppress this convection. By increasing the magnetic induction, it is observed that the intensity of the flow at the centre of the crucible reduces at a faster rate than near the wall. This phenomenon creates a stable and flat growth interface and the silicon distribution in the horizontal plane becomes relatively homocentric. The maximum velocity is found to obey a power law with respect to the Hartmann number Umax Ha⁻⁷/⁴

scholarly journals Three Dimensional Effect of Axial Magnetic Field to Suppress Convection in the Solvent of Ge0.98Si0.02 Grown By the Traveling Solvent Method

2021 ◽  
Author(s):  
Leily Abidi
Keyword(s):  
Magnetic Field ◽  
Stokes Equations ◽  
Axial Magnetic Field ◽  
Three Dimensional ◽  
Maximum Velocity ◽  
Navier Stokes ◽  
Growth Interface ◽  
Navier Stokes Equations ◽  
Solvent Method ◽  
Element Technique

A three dimensional numerical simulation of the effect of an axial magnetic field on the fluid flow, heat and mass transfer within the solvent of GE0.98Si0.02 grown by the travelling solvent method is presented. The full steady state Navier-Stokes equations, as well as the energy, continuity and the mass transport equations, were solved numerically using the finite element technique. It is found that a strong convective flow exists in the solvent, which is known to be undesirable to achieve a uniform crystal. An external axial magnetic field is applied to suppress this convection. By increasing the magnetic induction, it is observed that the intensity of the flow at the centre of the crucible reduces at a faster rate than near the wall. This phenomenon creates a stable and flat growth interface and the silicon distribution in the horizontal plane becomes relatively homocentric. The maximum velocity is found to obey a power law with respect to the Hartmann number Umax Ha⁻⁷/⁴

scholarly journals Influence of mineralization and injection flow rate on flow patterns in three-dimensional porous media

2019 ◽  
Vol 21 (27) ◽  
pp. 14605-14611 ◽  
Author(s):  
R. Moosavi ◽  
A. Kumar ◽  
A. De Wit ◽  
M. Schröter
Keyword(s):  
Porous Media ◽  
Flow Field ◽  
Flow Rate ◽  
Three Dimensional ◽  
Flow Patterns ◽  
Low Flow ◽  
Flow Rates ◽  
Injection Flow Rate ◽  
Injection Flow

At low flow rates, the precipitate forming at the miscible interface between two reactive solutions guides the evolution of the flow field.

A Wind Tunnel Study of Heat Transfer Over Complex Terrain

2003 ◽  
Author(s):  
Michelle Pantoya ◽  
Kenneth Shifflett ◽  
Walter Oler ◽  
William Burton
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Wind Energy ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Flow Patterns ◽  
Atmospheric Conditions ◽  
Unstable Flow ◽  
Scaled Model ◽  
Atmospheric Flow

Maximizing wind energy resources requires a detailed understanding of atmospheric flow behavior over complex topography. The objective of this research is to examine unstable flow behavior over a three-dimensional topographic model, representative of mesa terrain that is common in West Texas. The goal is to develop an understanding of how unstable atmospheric conditions caused by surface heating affect boundary layer flow patterns in the natural environment. This objective was accomplished by experimentally monitoring transient thermal behavior of narrow band liquid crystals over a scaled model. Photographic data was collected as the heated model was subjected to a cooler flow field. The transient isotherms result from cooling as the model is exposed to flow in an atmospheric boundary layer wind tunnel. Results suggest that flow patterns associated with unstable conditions can be explained by increased wind speeds on the lee side of a mesa followed by vigorous mixing causing increased cooling rates around the mesa sides. The results could be used to improve the accuracy of numerical atmospheric flow models, assess the feasibility of developing wind turbine sites, and increase the knowledge-base in order to advance wind energy forecasting techniques.

Axial evolution of forced helical flame and flow disturbances

2018 ◽  
Vol 844 ◽  
pp. 323-356 ◽  
Author(s):  
Travis E. Smith ◽  
Christopher M. Douglas ◽  
Benjamin L. Emerson ◽  
Timothy C. Lieuwen
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Unstable Flow ◽  
Natural Oscillations ◽  
Planar Velocity ◽  
Fluorescence Measurements ◽  
Flow Disturbances ◽  
Planar Laser ◽  
Acoustic Forcing

This paper presents 5 kHz stereo particle image velocimetry and OH planar laser induced fluorescence measurements of transversely forced swirl flames. The presence of transverse forcing on this naturally unstable flow both influences the natural instabilities, as well as amplifies disturbances that may not necessarily manifest themselves during natural oscillations. By manipulating the structure of the acoustic forcing field, both axisymmetric and helical modes are preferentially excited away from the frequency of natural instability. The paper presents a method for spatially interpolating the phase locked $r{-}z$ and $r{-}\unicode[STIX]{x1D703}$ planar velocity and flame position data, extracting the full three-dimensional structure of the helical disturbances. These helical disturbances are also decomposed into symmetric and anti-symmetric disturbances about the jet core, showing the subsequent axial evolution (in magnitude and phase) of each of these underlying disturbances. It is shown that out-of-phase acoustic forcing excites $m=\pm 1$ modes, but the flow field preferentially amplifies the counter-winding, co-rotating helical disturbance over the co-winding, counter-rotating helical disturbance. This causes the flow and flame to transition from a transverse flapping near the jet exit to a precessing motion further downstream. In contrast, in-phase forcing promotes axisymmetric $m=0$ disturbances which dominate the flow field over the entire axial domain. In both cases, the amplitudes of the anti-symmetric disturbances about the jet core grow with downstream distance before saturating and decaying, while the symmetric disturbances appear nearly negligible. It is suggested that this saturation and decay is due to linear effects (e.g. a negative spatial growth rate), rather than nonlinear interactions.

scholarly journals 3-D modeling and simulation of crystal growth of GE₀.₉₈ Si₀.₀₂ under the influence of various gravity levels, G-jitter and rotating magnetic field using traveling solvent method

2021 ◽  
Author(s):  
Mehdi Mohammadi Shemirani
Keyword(s):  
Magnetic Field ◽  
Space Station ◽  
Three Dimensional ◽  
Rotating Magnetic Field ◽  
Growth Interface ◽  
Solvent Method ◽  
Buoyancy Convection ◽  
Terrestrial Condition ◽  
Flow Heat ◽  
Micro Gravity

A three-dimensional numerical simulation was conducted to study the effect of a rotating magnetic (RMF) field on the fluid flow, heat transfer and mass transfer in the presence of various gravity levels by utilizing the traveling solvent method (TSM). The presence of the RMF suppressed the buoyancy convection in the GE₀.₉₈ Si₀.₀₂ solution zone in order to get homogeneity with a flat growth interface. It was found that the intensity of the flow at the centre of the crucible decreased at a faster rate compared to the flow near the walls when increasing magnetic field intensity is combined with a certain rotational speed. This behavior created a stable and uniform silicon distribution in the horizontal plane near the growth interface in the terrestrial condition. Different magnetic field intensities for different rotational speeds were examined in both terrestrial and micro-gravity conditions. The effects of residual acceleration, known as G-jitter, on board the International Space Station and European Space Orbiter were also investigated.

The Effect of Partial Admission on Multistage Radial Inflow Industrial Steam Turbine

2009 ◽  
Author(s):  
Yijin Li ◽  
Qun Zheng ◽  
Lanxin Sun
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Steam Turbine ◽  
Three Dimensional ◽  
Flow Patterns ◽  
Navier Stokes ◽  
Radial Turbine ◽  
Partial Admission ◽  
Aerodynamic Performances ◽  
Turbine Impeller

Aerodynamic performances of a partial admission multistage radial inflow turbine are investigated with numerical simulation. A three-dimensional unsteady Reynolds-averaged Navier–Stokes solver closed by Baldwin-Lomax model is applied for the computations. The flow field features of the first stages with partial admission are analyzed and discussed. Detailed flow patterns of the partial admission radial turbine impeller are presented here in this paper.

Usage of Axial and Rotating Magnetic Field to Process Ge0.98Si0.02 Crystal by the Traveling Heater Method

2007 ◽  
Author(s):  
T. J. Jaber ◽  
M. Z. Saghir
Keyword(s):  
Magnetic Field ◽  
Field Intensity ◽  
Magnetic Field Intensity ◽  
Axial Magnetic Field ◽  
Three Dimensional ◽  
Rotating Magnetic Field ◽  
Growth Interface ◽  
Buoyancy Convection ◽  
Traveling Heater Method ◽  
Flow Heat

A three-dimensional numerical simulation to study the effect of magnetic field on the fluid flow, heat and mass transfer is investigated. By applying axial and rotating magnetic field (RMF), an attempt was made to suppress the buoyancy convection in the Ge0.98Si0.02 solution zone in order to get homogeneity with flat growth interface. It was found that the intensity of the flow at the centre of the crucible decreased at a faster rate compared to the flow near the walls when increasing axial magnetic field intensity. This behaviour created a stable and uniform silicon distribution in the horizontal plane near the growth interface. Different magnetic field intensities for different rotational speeds (2, 7 and 10 rpm) were examined. The results showed that the RMF has a marked effect on the silicon concentration, changing it from convex to nearly flat when the magnetic field intensity increased.

scholarly journals Numerical and Experimental Comparative Study on the Flow-Induced Vibration of a Plane Gate

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1551
Author(s):  
Chunying Shen ◽  
Wei Wang ◽  
Shihua He ◽  
Yimin Xu
Keyword(s):  
Flow Field ◽  
Pressure Coefficient ◽  
Three Dimensional ◽  
Surface Profile ◽  
Computational Method ◽  
Unstable Flow ◽  
Flow Induced Vibration ◽  
Fluid Structure ◽  
Vof Model ◽  
Vibration Parameters

A numerical method is applied here to simulate the unstable flow and the vibration of a plane gate. A combination of the large eddy simulation (LES) method and the volume of fluid (VOF) model is used to predict the three-dimensional flow field in the vicinity of a plane gate with submerged discharge. The water surface profile, the streamline diagrams, the distribution of turbulent kinetic energy, the power spectrum density curve of the fluctuating pressure coefficient at typical points underneath the gate, and the complete vortex distribution around the gate are obtained by LES-VOF numerical calculation. The vibration parameters of the gate are calculated by the fluid-structure coupling interface transferring the hydrodynamic load. A simultaneous sampling experiment is performed to verify the validity of the algorithm. The calculated results are then compared with experimental data. The difference between the two is acceptable and the conclusions are consistent. In addition, the influence of the vortex in the slot on the flow field and the vibration of the gate are investigated. It is feasible to replace the experiment with the fluid-structure coupling computational method, which is useful for studying the flow-induced vibration mechanism of plane gates.

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