• Title/Summary/Keyword: 3-Dimensional Flow Field

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A Three-Dimensional Particle Focusing Channel Using the Positive Dielectrophoresis (pDEP) Guided by a Dielectric Structure Between Two Planar Electrodes (두 평면 전극 사이의 절연체 구조물에 의해 유도되는 양의 유전영동을 이용한 삼차원 입자 정렬기)

  • Chu, Hyun-Jung;Doh, Il;Cho, Young-Ho
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.3
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    • pp.261-264
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    • 2009
  • We present a three-dimensional (3D) particle focusing channel using the positive dielectrophoresis (pDEP) guided by a dielectric structure between two planar electrodes. The dielectric structure between two planar electrodes induces the maximum electric field at the center of the microchannel, and particles are focused to the center of the microchannel by pDEP as they flow from the single sample injection port. Compared to the previous 3D particle focusing methods, the present device achieves the simple and effective particle focusing function without any additional fluidic ports and top electrodes. In the experimental study, approximately 90 % focusing efficiency were achieved within the focusing length of 2mm, on both x-z plane (top-view) and y-z plane (side-view) for $2{\mu}m$-diameter polystyrene (PS) bead at the applied voltage over 15 Vp-p (square wave) and at the flow rate below 0.01 ${\mu}l$/min. The present 3D particle focusing channel results in a simple particle focusing method suitable for use in integrated microbiochemical analysis system.

NUMERICAL MODELING OF WIRE ELECTROHYDRODYNAMIC FLOW IN A WIRE-PLATE ESP

  • Chun, Young-Nam
    • Environmental Engineering Research
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    • v.11 no.3
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    • pp.164-171
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    • 2006
  • Numerical modeling of the flow velocity fields for the near corona wire electrohydrodynamic (EHD) flow was conducted. The steady, two-dimensional momentum equations have been computed for a wire-plate type electrostatic precipitator (ESP). The equations were solved in the conservative finite-difference form on a fine uniform rectilinear grid of sufficient resolution to accurately capture the momentum boundary layers. The numerical procedure for the differential equations was used by SIMPLEST algorithm. The Phoenics (Version 3.5.1) CFD code, coupled with Poisson's electric field, ion transport equations and the momentum equation with electric body force were used for the numerical simulation and the Chen-Kim ${\kappa}-{\varepsilon}$ turbulent model numerical results that an EHD secondary flow was clearly visible in the downstream regions of the corona wire despite the low Reynolds number for the electrode ($Re_{cw}=12.4$). Secondary flow vortices caused by the EHD increases with increasing discharge current or EHD number, hence pressure drop of ESP increases.

A Study of Supersonic Flow Around Lateral Jet Controlled Missile (측 추력 제어 미사일 주위의 초음속 유동현상 연구)

  • Min Byung-Young;Lee Jae-Woo;Byun Yung-Hwan;Hyun Jae-Soo
    • 한국전산유체공학회:학술대회논문집
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    • 2002.10a
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    • pp.28-34
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    • 2002
  • A computational study of supersonic flow around lateral jet controlled missile has been performed. For this study, three dimensional Navier-Stokes code(AADL3D) has been developed. Spalart-Allmaras one equation turbulence model has been implemented on the AADL3D code for relatively rapid computational time. For the validation of developed code, AADL3D, pressure distributions on an ogive-cylinder body has been compared with experimental data. Also, the shock structure of sonic jet on the flat plate in the supersonic flow field has been compared with experimental flow visualization result to see the analysis capability of freestream-jet interaction case. A case study has been performed through comparing the normal force coefficient and the moment coefficient of missile body for several jet flow conditions. Current results will be used to the optimum design of a lateral jet controlled missile.

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NUMERICAL INVESTIGATION ON BOTTOM GAP OF MICRO FLOW SENSOR

  • Abdullahl Mohd Zulkiefly;Kouta T;Kamijo Takuma;Yamamoto Makoto;Honami Shinji;Kamiunten Shoji
    • Journal of computational fluids engineering
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    • v.10 no.1
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    • pp.73-79
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    • 2005
  • Micro sensor is very useful for flow measurements in a number of engineering applications. Especially, it is necessary for the development of MEMS. This paper presents the 3D numerical simulation of flows around a micro flow sensor, which is mounted on a flat plate. The effects of the sensor configuration (i.e. bottom gap) and the Reynolds number on the flow field are numerically investigated. The numerical results indicate that the bottom gap clearly affects the flow fields over the top surface of the sensor. The Reynolds numbers also show a significant influence on the flow nature, especially on the recirculation zone at downstream of the sensor. The present results illustrate a certain improvement on the flow field for the sensor installed at O.5mm above the wall with four pillars, comparing with that directly mounted on the wall.

CFD simulation of vortex-induced vibration of free-standing hybrid riser

  • Cao, Yi;Chen, Hamn-Ching
    • Ocean Systems Engineering
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    • v.7 no.3
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    • pp.195-223
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    • 2017
  • This paper presents 3D numerical simulations of a Free Standing Hybrid Riser under Vortex Induced Vibration, with prescribed motion on the top to replace the motion of the buoyancy can. The model is calculated using a fully implicit discretization scheme. The flow field around the riser is computed by solving the Navier-Stokes equations numerically. The fluid domain is discretized using the overset grid approach. Grid points in near-wall regions of riser are of high resolution, while far field flow is in relatively coarse grid. Fluid-structure interaction is accomplished by communication between fluid solver and riser motion solver. Simulation is based on previous experimental data. Two cases are studied with different current speeds, where the motion of the buoyancy can is approximated to a 'banana' shape. A fully three-dimensional CFD approach for VIV simulation for a top side moving Riser has been presented. This paper also presents a simulation of a riser connected to a platform under harmonic regular waves.

Numerical investigation of ceramic particle movement for injected gas flow rate in cyclone separator system (사이클론 분리기 시스템 내에서의 가스 주입 유속에 따른 세라믹 입자 거동 전산모사)

  • 우효상;심광보;정용재
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.13 no.3
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    • pp.145-151
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    • 2003
  • Using computational fluid dynamics (CFD) method, we investigated three-dimensional fluid flow field and particle movement with respect to the injected gas flow rate variation in typical cyclone separator system. The results of numerical investigation were deduced by coupling the analysis of fluid flow field with Wavier-stokes equation and the tracking of the particle trajectory with Langrangian approach. It was shown that the increasing of injected gas flow rate resulted in the increasing of pressure loss in the separator. This change of inner pressure had an effect on an aspect of the fluid flow in the separator. Particle movement was determined by fluid flow in the separator and was fully depended on a diameter of particles under the fixed flow rate. Increasing of injected gas flow rate was led to an increasing of the trace of particle, so the particles moved to the lower part of the separator. For this reason, the minimum diameters of the particles were decreased and increased the separation rate under the fixed particle diameter. In conclusion, the changes of injected gas flow rate have an important factor to the fluctuation of the fluid flow field and particle trajectory in the separator.

Numerical Study on Fluid Flows and Stirring in a Circular Cylinder Subjected to Circulatory Oscillation (회전요동하는 원통내의 유동 및 교반특성을 위한 수치해석적 연구)

  • Kim, Hyeun Mihn;Suh, Yong Kweon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.3
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    • pp.408-418
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    • 1999
  • Incompressible flow inside a circular cylinder Including periodically oscillating free surface waves was studied primarily by using a numerical method. We developed a finite difference scheme based on the MAC method applicable to three-dimensional free-surface flows, and applied it to the present flow model to study tho flow characteristics as well as the fluid stirring. To verify the validity of our scheme, we performed a simple experiment for flow visualization. We found that the numerical results show a reasonable agreement with the observed flow patterns.

An Analysis of Surface irrigation's Hydraulic Characteristics at a Paddy Field Using a Two-Dimensional Numerical Model (2차원 유한체적 수치모형을 이용한 논의 지표관개 수리특성 분석)

  • Park, Seung-Woo;Park, Jong-Min;Kang, Min-Goo
    • Journal of The Korean Society of Agricultural Engineers
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    • v.46 no.4
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    • pp.3-11
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    • 2004
  • A finite volume model is developed to simulate the surface irrigation at a paddy field. The model's capabilities are validated through comparison with the simulafed results and the observed data obtained by various experimental tests, and the simulated results are in good agreement with the observed pending depth. The result of surface irrigation simulation shows that the longer the paddy field's the length of long-sided becomes, the longer the advance and storage time is taken. To analyze surface irrigation performance with variable inflow rate, three patterns of flow variation-constant rate, initially high then low, and initially low then high-were studied. The results show that at the pattern with initially high followed by low during the latter half of the irrigation the advance time is shortest, but the pending depth of irrigation completion and irrigation effiency are the little difference between irrigation patterns.

Three Dimensional Flow Structure under Rotating Stall in an Axial Flow Fan (주기적 선회실속이 발성하는 축류홴의 3차원 유동구조)

  • Kang, Chang Sik;Shin, You Hwan;Kim, Kwang Ho
    • 유체기계공업학회:학술대회논문집
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    • 2002.12a
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    • pp.105-110
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    • 2002
  • Experimental study was conducted to reveal the instability such as leakage flow and rotating stall in an axial flow fan. For this study, unsteady total pressure probe and multi-hole pressure probe were specially designed for measuring the flow field upstream and downstream of rotor. The measured pressure signal was analyzed by Single and Double Phase Locked Averaging Technique. From the result of total pressure fields at inlet and outlet of the rotor, the useful information on the structure of the stall cell in radial direction was provided. Also, detailed flow measurements were carried out with a specially designed high frequency multi-hole pressure probe, providing some insight to the leakage flow and their interation.

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The Characteristics of Triple Hot-Wire Probe and It's Evaluation (3축 열선 PROBE의 특성과 그 평가)

  • Kim, Kyung-hoon
    • Journal of the Korean Society for Precision Engineering
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    • v.5 no.3
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    • pp.48-62
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    • 1988
  • A triple hot-wire probe has an essential potentiality for the measure- ment of an instantaneous velocity vector in a three dimensional unsteady flow with large amplitude of velocity fluctuations, the key problems asso- ciated with this instrument are the directional range of applicability and the accuracy. This present paper is concerned with a new method of the techniques of calibration and data processing to estimate the three dimensional flow field using an arbitrary shaped triple hot-wire probe. The method is not based on the assumptions of orthogonality or symmetry and it is especially useful for applications to a hand-made probe where probe geometry is not accurately known. The test application is made to evaluate the effect of cone angles of symmetric non-orthogonal probe.

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