• 제목/요약/키워드: variable viscosity

검색결과 90건 처리시간 0.027초

머시응고에 대한 속도감쇠 기법이 정상상태 머시영역에 미치는 영향 (Effect of the Velocity Suppression Techniques for a Mushy Solidification on Steady-state Mushy Region)

  • 김우승;김덕수
    • 대한기계학회논문집B
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    • 제22권12호
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    • pp.1657-1668
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    • 1998
  • In the analysis of a mushy solidification system with natural convection using a fixed grid method, the enthalpy method has been used to account for the release of latent heat. The variable viscosity, Darcy source, and hybrid methods have been employed for the velocity suppression in a mushy region. The choice of the values of solid viscosity and permeability constant in conjunction with the Darcy source term plays an important role in forming the location and shape of the phase boundaries. In this work the effects of these major parameters related to steady-state behavior in the system of mushy solidification are investigated through a simple test problem. The effective specific heat based on the spatial gradients of the enthalpy and temperature is adopted for the treatment of the release of latent heat. The effects of the Prandtl and Rayleigh numbers on the shape of mushy region are examined using the hybrid method.

Flow and Heat Transfer Analysis of Copper-water Nanofluid with Temperature Dependent Viscosity Past a Riga Plate

  • Ahmad, A.;Ahmed, S.;Abbasi, F.M.
    • Journal of Magnetics
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    • 제22권2호
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    • pp.181-187
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    • 2017
  • Flow of electrically conducting nanofluids is of pivotal importance in countless industrial and medical appliances. Fluctuations in thermophysical properties of such fluids due to variations in temperature have not received due attention in the available literature. Present investigation aims to fill this void by analyzing the flow of copper-water nanofluid with temperature dependent viscosity past a Riga plate. Strong wall suction and viscous dissipation have also been taken into account. Numerical solutions for the resulting nonlinear system have been obtained. Results are presented in the graphical and tabular format in order to facilitate the physical analysis. An estimated expression for skin friction coefficient and Nusselt number are obtained by performing linear regression on numerical data for embedded parameters. Results indicate that the temperature dependent viscosity alters the velocity as well as the temperature of the nanofluid and is of considerable importance in the processes where high accuracy is desired. Addition of copper nanoparticles makes the momentum boundary layer thinner whereas viscosity parameter does not affect the boundary layer thickness. Moreover, the regression expressions indicate that magnitude of rate of change in effective skin friction coefficient and Nusselt number with respect to nanoparticles volume fraction is prominent when compared with the rate of change with variable viscosity parameter and modified Hartmann number.

Research on the influence of union-pay M-payment quality and brand personality on user viscosity

  • Liu, Zi-Yang;Wang, Jun-Lin;Liu, Jiayu;Liu, Xiao-yin;Liao, Kai
    • 한국컴퓨터정보학회논문지
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    • 제25권4호
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    • pp.157-163
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    • 2020
  • 이 연구의 목적은 서비스 품질 및 브랜드 특성의 관점에서 Union-Pay 모바일 결제가 사용자 점도에 미치는 영향을 탐색하는 것이다. 앞으로 중국Union-Pay가 모바일결제 시장에서 안정적이고 충실한 사용자 그룹을 확보하는 것이 의미가 있다. 이 연구는 SPSS22.0 및 AMOS 통계 분석 도구를 사용하여 경험적 연구를 수행을 했다. 본 연구는 모바일 서비스 품질을 사용하고 브랜드 성격은 독립 변수이고, 사용자의 점도는 종속 변수이며, China Union-Pay 모바일 결제와 관련하여 사용자의 점도에 미치는 영향을 연구하였다. 연구 분석결과에 따르면, 서비스 품질이 사용자가 인식 한 가치에 유의 한 영향을 미친다는 결과 나타났다. 서비스 품질은 사용자 점도에 유의 한 양의 관계를 갖다. 인식 된 값은 사용자 점도에 유의한 양의 효과를 나타났다. 사용자에 대한 브랜드 특성이 사용자 점도에 유의한 양의 효과를 나타났다. 브랜드 성격은 사용자가 인식 한 가치에 유의 한 양의 관계 영향을 미친다. 이 연구를 통해 모바일 결제 기업의 산업 발전에 대한 제안을 했고 모바일 결제발전에 대한 더 나은 의견을 제시 하였다.

QUADRATIC B-SPLINE FINITE ELEMENT METHOD FOR THE BENJAMIN-BONA-MAHONY-BURGERS EQUATION

  • Yin, Yong-Xue;Piao, Guang-Ri
    • East Asian mathematical journal
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    • 제29권5호
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    • pp.503-510
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    • 2013
  • A quadratic B-spline finite element method for the spatial variable combined with a Newton method for the time variable is proposed to approximate a solution of Benjamin-Bona-Mahony-Burgers (BBMB) equation. Two examples were considered to show the efficiency of the proposed scheme. The numerical solutions obtained for various viscosity were compared with the exact solutions. The numerical results show that the scheme is efficient and feasible.

Thermoviscoelastic orthotropic solid cylinder with variable thermal conductivity subjected to temperature pulse heating

  • Abouelregal, A.E.;Zenkour, A.M.
    • Earthquakes and Structures
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    • 제13권2호
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    • pp.201-209
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    • 2017
  • This work aims to analyze the thermo-viscoelastic interaction in an orthotropic solid cylinder. The medium is considered to be variable thermal conductivity and subjected to temperature pulse. Analytical solution based on dual-phase-lags model with Voigt-type for behavior of viscoelastic material has been effectively proposed. All variables are deduced using method of Laplace transforms. Numerical results for different distribution fields, such as temperature, displacement and stress components are graphically presented. Results are discussed to illustrate the effect of variability thermal conductivity parameter as well as phase-lags and viscoelasticity on the field quantities. Results are obtained when the viscosity is ignored with and without considering variability of thermal conductivity. A comparison study is made and all results are investigated.

수경성 물질용 분리저감제를 사용한 무다짐 콘크리트 실용화 연구 (Practical Use of Self-compacting Concrete by Hydraulic Composition Containing a Segregation-Reducing Agent)

  • 손유신;이승훈;김규동;김경태
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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    • pp.275-280
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    • 2001
  • Recently, self-compacting concrete is applied in order to achieve workability improvement and rationalization in construction. But self-compacting concrete using viscosity agent has a difficulty in practical use because viscosity agent is invested small quantity and by man-power. Therefore in this paper we have been focused on the development and practical use of self-compacting concrete by hydraulic composition containing the segregation-reducing agent. According to mix variable, we find out right quantity of water, binder and rate of admixture replacement, and also we find out the optimum mix proportion. In the result, self-compacting concrete by hydraulic composition containing the segregation reducing agent gave satisfaction with standard and its demand will increase in the future.

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ER유체를 이용한 미세 연마 가공 (Micro Plishing using Electorheological fluid)

  • 김욱배;이성재;박철우;이상조
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2000년도 추계학술대회 논문집
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    • pp.850-853
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    • 2000
  • It is well-known that Electro-rheological(ER) fluid is a material(suspension) which shows the dramatic change of rheological properties under an electric field. Using these properties, the concept that variable apparent viscosity of ER fluid could be applicable to the polishing for micro parts was introduced. It was investigated that how it works for polishing and how it affects ER effect when abrasives were mixed with an ER fluid. Therefore a few structures for polishing using ER fluid was suggested and evaluated by means of experiments. In this paper, fundamental mechanism and experimental results are described.

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고점도 펄프를 위한 새로운 한지 펄프화법의 개발(제1보) - 닥나무 백피의 상압 펄프화 특성 - (Development of High Viscosity Pulping Method for Korean Paper (I) - Atmospheric Pressure Pulping Characteristics of Paper Mulberry White Bast -)

  • 이상현;최태호
    • 펄프종이기술
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    • 제43권2호
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    • pp.57-65
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    • 2011
  • Pulping of paper mulberry (Broussonetia kazinoki) white bast has been examined by novel atmospheric pressure pulping methods. The viscosity of pulp has been found to be highly sensitive and variable with pulping methods. Therefore, selections of pulping chemicals and conditions are very important. Two kinds of pulping procedures were employed for the high viscosity pulp manufacturing. The one is ammonium oxalate treatment and the other is sodium chlorite and acetic acid treatment. Not only chemical components and pulp yields which of paper mulberry white bast but also water retention value (WRV), whiteness index, yellowness index, and colors of every pulp were examined. The hot water, 1% NaOH, and ethanol-benzene extractives which of paper mulberry white bast were 4.48%, 28.45%, and 2.84%, respectively. The contents of holocellulose, lignin, and ash were 90.66%, 1.05%, and 2.18%, respectively. In the pulp yields, group 1 which treated with only ammonium oxalate were 77.04-81.71%, group 2 which treated with ammonium oxalate and acidified sodium chlorite separately and washed between first and second stages were 64.15-83.90%, group 3 which treated with ammonium oxalate and acidified sodium chlorite separately and not washed between first and second stages were 57.35-73.17%, and group 4 which treated with mixed ammonium oxalate and acidified sodium chlorite were 66.58-68.43%. The pulps treated with acidified sodium chlorite showed high whiteness index, but the pulps treated with only ammonium oxalate showed high yellowness index. Variations in the combinations of treatments resulted in different pulp characteristics.

극저온 정압 저널베어링의 성능해석에 관한 연구 : 난류유동, 압력강하, 가변 밀도 및 점도의 영향 (A Study on Performance Analysis of Cryogenic Hydrostatic Journal Bearings : the Effects of Turbulent Flow, Pressure Drop and Variable Liquid Properties)

  • 김성기;강지훈;김경웅
    • Tribology and Lubricants
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    • 제19권3호
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    • pp.139-145
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    • 2003
  • In this paper, static characteristics of a cryogenic hydrostatic journal bearing which has 2-rows staggered recesses are numerically analyzed. The regime of operation of this bearing is fully turbulent with large fluid inertia effects. The turbulent lubrication equation is solved under the assumption that turbulence parameters are decided by the Reynolds numbers. Pressure drop caused by inertia effect at the recess edge is considered in this analysis. Also density and viscosity of working fluid are considered as function of only pressure. Numerical results for a cryogenic Hydrostatic journal bearing show pressure distribution, load capacity, flow rate, and recess pressure. The effects of turbulent flow, pressure drop and variable liquid properties are discussed.

온도 변화의 영향을 고려한 커넥팅 로드 베어링의 EHL 해석 (EHL Analysis of connecting Rod Bearings Considering Effects of Temperature Variation)

  • 김병직;김경웅
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2000년도 제31회 춘계학술대회
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    • pp.114-120
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    • 2000
  • EHL analysis of connecting rod bearing is proposed which includes effects of temperature variation in lubrication film. Lubrication film temperature is treated as a time-dependent, two-dimensional variable which is averaged over the film thickness, while connecting rod big end temperature is assumed to be time-independent and three-dimensional. It is assumed that a portion of the heat generated by viscous dissipation in the lubrication Him is absorbed by the film itself, and the remainder flows into the bearing surface. Mass-conserving cavitation algorithm is applied and the effect of variable viscosity is included to solve the Reynolds equation. Simulation results of the connecting rod bearing of internal combustion engine are presented. It is shown that the temperature variation has remarkable effects on the bearing performance. It is concluded that the EHL analysis considering effects of the temperature variation is strongly recommended to predict the bearing performance of connecting rod big end On internal combustion engine.

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