• 제목, 요약, 키워드: variable viscosity

검색결과 90건 처리시간 0.023초

Magnetohydrodynamic peristalsis of variable viscosity Jeffrey liquid with heat and mass transfer

  • Farooq, S.;Awais, M.;Naseem, Moniza;Hayat, T.;Ahmad, B.
    • Nuclear Engineering and Technology
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    • v.49 no.7
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    • pp.1396-1404
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    • 2017
  • The mathematical aspects of Dufour and Soret phenomena on the peristalsis of magnetohydrodynamic (MHD) Jeffrey liquid in a symmetric channel are presented. Fluid viscosity is taken variably. Lubrication approach has been followed. Results for the velocity, temperature, and concentration are constructed and explored for the emerging parameters entering into the present problem. The plotted quantities lead to comparative study between the constant and variable viscosities fluids. Graphical results indicate that for non-Newtonian materials, pressure gradient is maximum, whereas pressure gradient is slowed down for variable viscosity. Also both velocity and temperature in the case of variable viscosity are at maximum when compared with results for constant viscosity.

Effect of variable viscosity on combined forced and free convection boundary-layer flow over a horizontal plate with blowing or suction

  • Mahmoud, Mostafa A.A.
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.11 no.1
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    • pp.57-70
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    • 2007
  • The effects of variable viscosity, blowing or suction on mixed convection flow of a viscous incompressible fluid past a semi-infinite horizontal flat plate aligned parallel to a uniform free stream in the presence of the wall temperature distribution inversely proportional to the square root of the distance from the leading edge have been investigated. The equations governing the flow are transformed into a system of coupled non-linear ordinary differential equations by using similarity variables. The similarity equations have been solved numerically. The effect of the viscosity temperature parameter, the buoyancy parameter and the blowing or suction parameter on the velocity and temperature profiles as well as on the skin-friction coefficient and the Nusselt number are discussed.

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NON LINEAR VARIABLE VISCOSITY ON MHD MIXED CONVECTION HEAT TRANSFER ALONG HIEMENZ FLOW OVER A THERMALLY STRATIFIED POROUS WEDGE

  • Kandasamy, R.;Hashim, I.;Ruhaila, K.
    • Journal of applied mathematics & informatics
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    • v.26 no.1_2
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    • pp.161-176
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    • 2008
  • The effect of variable viscosity on MHD mixed convection Hiemenz flow over a thermally stratified porous wedge plate has been studied in the presence of suction or injection. The wall of the wedge is embedded in a uniform Darcian porous medium in order to allow for possible fluid wall suction or injection and has a power-law variation of the wall temperature. An approximate numerical solution for the steady laminar boundary-layer flow over a wall of the wedge in the presence of thermal diffusion has been obtained by solving the governing equations using numerical technique. The fluid is assumed to be viscous and incompressible. Numerical calculations are carried out for different values of dimensionless parameters and an analysis of the results obtained shows that the flow field is influenced appreciably by the magnetic effect, variable viscosity, thermal stratification and suction / injection at wall surface. Effects of these major parameters on the transport behaviors are investigated methodically and typical results are illustrated to reveal the tendency of the solutions. Comparisons with previously published works are performed and excellent agreement between the results is obtained.

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Bionic Study of Variable Viscosity on MHD Peristaltic Flow of Pseudoplastic Fluid in an Asymmetric Channel

  • Khan, Ambreen A.;Muhammad, Saima;Ellahi, R.;Zia, Q.M. Zaigham
    • Journal of Magnetics
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    • v.21 no.2
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    • pp.273-280
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    • 2016
  • In this paper, the peristaltic flow of Psedoplastic fluid with variable viscosity in an asymmetric channel is examined. The bionic effects by means of magnetohydrodynamics (MHD) are taken into account. The assumptions of long wave length and low Reynolds number are taken into account. The basic equations governing the flow are first reduced to a set of ordinary differential equation by using appropriate transformation for variables and then solve by using perturbation method. The effect of physical parameters on the pressure rise, velocity and pressure gradient are illustrated graphically. The trapping phenomenon is analyzed through stream lines. A suitable comparison has also been made as a limiting case of the considered problem.

대류 조건하의 가변 점성 유체층의 선형 안전성 (Linear Stability of Variable-Viscosity Fluid Layer under Convection Boundary Condition)

  • 송태호
    • 대한기계학회논문집
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    • v.16 no.1
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    • pp.132-141
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    • 1992
  • 본 연구에서는 실제적으로 베나트 대류의 발생시 유체층의 상하면은 적당한 대류 열전달 계수를 가지고 있게 되는데, 이와 같은 경계 조건을 가진 가변 점성 유 체의 안정성은 연구된 바가 없다. 이에 따라 본 연구를 수행하게 되었으며 유체의 점성이 지수 함수적으로 (.nu.=.nu.o exp(-CT)) 변화할 경우를 관찰하였다. Fig.1은 대 상이 된 유체층을 보인 것으로 하부는 고정되어 있고 상부는 고정되어 있거나 자유 표 면 상태이다. 유체층의 하부는 상부보다 더 뜨겁게 되어 있는데, 이것은 유체층의 상부는 차가운 주위로 열을 빼앗기며 하부는 뜨거운 주위로부터 가열되기 때문이다. 이때 상하부의 냉각 및 가열 경계 조건은 대류경계 조건으로 주어진다. 열팽창 계수 는 양이며 온도의 증가에 따라 점성은 감소한다.이와 같은 온도-점성 관계, 수력학 적 경계조건, 열적 조건등은 프란틀 수가 큰 유체에서 표본적으로 나타나는 것들로서 선형적 안정 이론을 적용하여 옳은 결과를 얻을 수 있다.

A modified scaled variable reduced coordinate (SVRC)-quantitative structure property relationship (QSPR) model for predicting liquid viscosity of pure organic compounds

  • Lee, Seongmin;Park, Kiho;Kwon, Yunkyung;Park, Tae-Yun;Yang, Dae Ryook
    • Korean Journal of Chemical Engineering
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    • v.34 no.10
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    • pp.2715-2724
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    • 2017
  • Liquid viscosity is an important physical property utilized in engineering designs for transportation and processing of fluids. However, the measurement of liquid viscosity is not always easy when the materials have toxicity and instability. In this study, a modified scaled variable reduced coordinate (SVRC)-quantitative structure property relationship (QSPR) model is suggested and analyzed in terms of its performance of prediction for liquid viscosity compared to the conventional SVRC-QSPR model and the other methods. The modification was conducted by changing the initial point from triple point to ambient temperature (293 K), and assuming that the liquid viscosity at critical temperature is 0 cP. The results reveal that the prediction performance of the modified SVRC-QSPR model is comparable to the other methods as showing 7.90% of mean absolute percentage error (MAPE) and 0.9838 of $R^2$. In terms of both the number of components and the performance of prediction, the modified SVRC-QSPR model is superior to the conventional SVRC-QSPR model. Also, the applicability of the model is improved since the condition of the end points of the modified model is not so restrictive as the conventional SVRC-QSPR model.

Study molded part quality of plastic injection process by melt viscosity evaluation

  • Lin, Chung-Chih;Wu, Chieh-Liang
    • Advances in materials Research
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    • v.3 no.2
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    • pp.91-103
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    • 2014
  • A study that demonstrates how to investigate the molded part quality and the consistency of injection process based on the rheological concept is proposed. It is important for plastic material whose melt viscosity is variable with respect to the processing condition. The formulations to couple the melt viscosity with injection pressure and fill time are derived first. Taking calculations of the measured pressure and the time by using these formulations, the melt viscosity in injection process can be determined on machine. As the relation between the injection speed and the melt viscosity is constructed, the influences of the setting parameter of injection machine on the molded part quality can be investigated through evaluating the state of the melt viscosity. In addition, a pressure sensor bushing (PSB) designed with a quick installation feature is also provided and validated. The results show that a higher injection speed improves the tensile strength of the molded part but also the consistency of the molded part quality. This work provides an alternative to evaluate the molding quality scientifically.

그라우트재의 물시멘트비 및 혼합속도에 의한 물성변화에 관한 연구 (A Study on the Variation of Physical Properties by the Water to Cement Ratio and the Mixing Speed for Grout Materials)

  • 천병식;김진춘;장의웅;송성호;이준우
    • 한국지반공학회:학술대회논문집
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    • pp.445-452
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    • 2001
  • Generally, OPC(ordinary portland cement) is used for grouting in Korea, and bentonite has usually been added to prevent the deposition of cement particles. The dispersion of CB(cement bentonite) grout is influenced by variable factors i.e. water to cement ratio, particle size of cement, kind of bentonite, adding volume, methods of adding, viscosity of CB grout materials and curdling time. Among variable factors, the viscosity of CB grout materials is influenced by the dispersion, and dispersion is improved as increasing the mixing speed. In this paper, described a suitable mixing speed of the High Speed Mixer in field, engineering characteristics of CB grout materials vary with the water to cement ratio and the mixing speed as well as confirming the state of dispersion.

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INFLUENCE OF THERMAL CONDUCTIVITY AND VARIABLE VISCOSITY ON THE FLOW OF A MICROPOLAR FLUID PAST A CONTINUOUSLY MOVING PLATE WITH SUCTION OR INJECTION

  • Salem, A.M.;Odda, S.N.
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.9 no.2
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    • pp.45-53
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    • 2005
  • This paper investigates the influence of thermal conductivity and variable viscosity on the problem of micropolar fluid in the presence of suction or injection. The fluid viscosity is assumed to vary as an exponential function of temperature and the thermal conductivity is assumed to vary as a linear function of temperature. The governing fundamental equations are approximated by a system of nonlinear ordinary differential equations and are solved numerically by using shooting method. Numerical results are presented for the distribution of velocity, microrotation and temperature profiles within the boundary layer. Results for the details of the velocity, angular velocity and temperature fields as well as the friction coefficient, couple stress and heat transfer rate have been presented.

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채널 유동에서 점성이 단일 입자 혼합 유동의 suspension에 미치는 영향 (Effect of Fluid Viscosity on the Suspension of a Single Particle in Channel Flow)

  • 최형권
    • 대한기계학회논문집B
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    • v.33 no.3
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    • pp.194-200
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    • 2009
  • Suspension of a single solid particle in a channel flow with a constant pressure gradient is studied numerically. The interaction of a circular particle with a surrounding Newtonian fluid is formulated using a combined formulation. Numerical results are presented using two dimensionless variables: the sedimentation Reynolds number and the generalized Froude number. From the present results, it has been shown that a solid particle is suspended at a smaller generalized Froude number as the viscosity of the surrounding fluid increases. The time taken for equilibrium position is found to be smaller as fluid viscosity increases when both : the sedimentation Reynolds number and the generalized Froude number are the same while, at the same situation, the dimensionless time taken for equilibrium position is to be nearly the same regardless of fluid viscosity when a dimensionless time variable is introduced