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مرکز اطلاعات علمی SID1
اسکوپوس
مرکز اطلاعات علمی SID
ریسرچگیت
strs
Issue Info: 
  • Year: 

    2020
  • Volume: 

    6
  • Issue: 

    3
  • Pages: 

    531-542
Measures: 
  • Citations: 

    0
  • Views: 

    30958
  • Downloads: 

    36449
Abstract: 

This study presents the computational analysis of three dimensional Casson and Carreau nanoFluid flow concerning the convective conditions. To do so, the flow equations are modified to nonlinear system of ODEs after using appropriate self-similarity functions. The solution for the modified system is evaluated by numerical techniques. The results show the impacts of involving variables on flow characteristics and the outcomes of the friction factors are evaluated as well. In this study, the outcomes to local Nusselt number and Sherwood numbers are evaluated. Favourable comparison is performed with previously available outcomes. The achieved results are similar to solutions obtained by other researchers. The results are presented for flow characteristics in the case of Casson and Carreau Fluids. Velocities are reduced for the growing values of permeability and velocity slip parameters in case of Casson and Carreau nanoFluids. Temperature field enhances with the hike in the estimations of thermophoresis parameter and the thermal Biot number in case of Casson and Carreau nanoFluids. Enhancing values of velocity slip parameter results in decrease in the skin friction coefficients and the rate of heat transfer, and rise in the rate of mass transfer in case of Casson and Carreau nanoFluids.

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    48
  • Issue: 

    1 (82)
  • Pages: 

    105-113
Measures: 
  • Citations: 

    0
  • Views: 

    606
  • Downloads: 

    197
Abstract: 

In this study non-Newtonian Fluid flow in two-dimensional channel with a circular obstacle has been studied using lattice Boltzmann method. The Carreau-Yasuda non-Newtonian model is used to simulate the non-Newtonian Fluid behavior. The exponential model with different temperature-thinning coefficients is utilized to investigate the temperature-dependent viscosity of non-Newtonian Fluid. Regarding to the local properties of the lattice Boltzmann method, the shear-dependent and temperature-dependent properties of Carreau-Yasuda non-Newtonian Fluid are easily modeled with two-order accuracy. The validation of results for Fluid flow and heat transfer parameters are completed, successfully. Results show a reduction in the power index of Carreau-Yasuda non-Newtonian model leads to growth of average Nusselt number, especially in high Reynolds numbers. Simulations show an increasing in the Carreau number causes to increase of wakes formed behind the cylinder. The results of drag coefficient versus temperaturethinning coefficient shows that the temperature-dependent viscosity has a significant effect on the flow field; in a way that a growth in the temperature-thinning coefficient leads to increase and decrease of drag coefficient and size of the vortices, respectively.

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Issue Info: 
  • Year: 

    2020
  • Volume: 

    6
  • Issue: 

    2
  • Pages: 

    307-319
Measures: 
  • Citations: 

    0
  • Views: 

    21367
  • Downloads: 

    14619
Abstract: 

In the current study, non-Newtonian flow pattern and heat transfer in an enclosure containing a tilted square are examined. In order to numerically simulate the problem, the mesoscopic lattice Boltzmann method is utilized. The non-Newtonian Carreau-Yasuda model is employed. It is able to adequately handle the shear-thinning case. The simulation results of flow and heat transfer have been successfully verified with the previous studies. Several parameters such as Nusselt number, Drag coefficient, and Carreau number are investigated in details. Considering the temperature-dependent viscosity, it is seen that with increasing the temperature-thinning index, the drag coefficient increases, but the Nusselt number decreases. By rotating the square obstacle, the results display that increasing the angle of inclination from zero to 45 degrees, increases both the drag coefficient and the Nusselt number. Also, the highest rate of heat transfer occur at the angle of 45 degrees (diamond); however it has a negative impact on the Drag coefficient.

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گارگاه ها آموزشی
Issue Info: 
  • Year: 

    2019
  • Volume: 

    5
  • Issue: 

    2
  • Pages: 

    390-401
Measures: 
  • Citations: 

    0
  • Views: 

    23621
  • Downloads: 

    30421
Abstract: 

The present investigation draws scholars' attention to the effect of exponential variable viscosity modeled by Vogel and variable permeability on stagnation point flow of Carreau NanoFluid over an electromagnetic plate through a porous medium. Brownian motion and thermophoretic diffusion mechanism are taken into consideration. An efficient fourth-order RK method along with shooting technique are implemented to obtain the required solution of the non-dimensional modeled equations. The contribution of the present study is that augmented electromagnetic field strength due to the suitable arrangement of the plate and that of porosity parameter yield an accelerated motion while that of viscosity parameter produces retarded motion of shear-thickening Fluid, contrary to shear-thinning Fluid. At the same time, it discusses the inclusion of porous matrix which controls the thermal as well as concentration boundary layers, while enhanced Brownian motion exhibits diametrically opposite trend for them in response to shear-thickening Fluid.

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Issue Info: 
  • Year: 

    1401
  • Volume: 

    11
  • Issue: 

    3
  • Pages: 

    383-396
Measures: 
  • Citations: 

    0
  • Views: 

    13
  • Downloads: 

    2
Abstract: 

زمینه و هدف: این تحقیق به بررسی نحوه پراکنش آلاینده های ناشی از سناریو اشتعال انبار نفت با استفاده از نرم افزار انسیس فلوینت پرداخته است و برای اولین بار در کشور سناریوهای خطرناک و غیرمنتظره انفجار و اشتعال در سایت های نفتی را با استفاده ازاین نرم افزار مورد بررسی قرار داده و هدفش حفظ دارایی ها جانی و مالی مناطق اطراف انبار نفت است. مواد و روش ها: به منظور تعیین میزان آلاینده های حاصل از سوختن مخازن، از نرم افزار Ansys Fluent 15 استفاده شد. این نرم افزار پارامترهای موثر سرعت، جهت باد، دمای محیط، میزان انتشار آلاینده ها و پایداری جو را درنظرگرفته و می تواند غلظت آلاینده های گوناگون را در فواصل مختلف از انبارها پیش بینی نماید. نتایج خروجی این نرم افزار وارد محیط مشینگ شد و درنهایت نقشه پراکندگی آلودگی در محدوده ای به وسعت چهار کیلومتر تا ارتفاع 200 متر به دست آمد. یافته ها: در این پژوهش، تاثیر اشتعال و انفجار انبار نفت بر روی محیط زیست و محیط مسکونی اطراف محوطه انبار مورد تحلیل عددی قرار گرفت. با توجه به جمع بندی نتایج در شرایط بحرانی که سرعت وزش باد بالا باشد، جهت وزش باد تاثیر بسزایی در مناطق تحت تاثیر خواهد داشت، بطوری که افزایش دمای تا حدود 60 درجه سلسیوس و بالاتر و نیز غلظت آلاینده های CO, CO2, NOX, SO2 همگی در فواصلی حدود 800 متر تا یک کیلومتر در مناطق انبار غله کرج، شهرک بنفشه، رزکان نو، محوطه راه آهن کرج، سرحدآباد و شهرک وحدت با توجه به جهت وزش باد به میزان 30 تا 40 درصد بالاتر از استاندارد، مورد انتظار است. نتیجه گیری: نتایج این تحقیق نشان داد اگر آتش سوزی در مخازن رخ دهد. مناطق مسکونی و صنعتی مختلفی در مسیر پخش و پراکنش آلودگی بسیار بالاتر از حد استاندارد می باشند. با توجه به شدت آلودگی تولیدشده و وسعت مناطق درگیر بیماری های تنفسی، خسارت های جانی و مالی قابل پیش بینی است.

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Issue Info: 
  • Year: 

    2017
  • Volume: 

    10
  • Issue: 

    6
  • Pages: 

    1785-1798
Measures: 
  • Citations: 

    0
  • Views: 

    29405
  • Downloads: 

    36034
Abstract: 

The paper investigates the peristaltic pumping of an incompressible non-Newtonian Fluid in an elastic tube with long wavelengths and low Reynolds number approximations. Carreau Fluid model is considered for present study to describe the peristaltic flow characteristics of non-Newtonian Fluid in an elastic tube. Carreau Fluid is a generalized Newtonian Fluid which exhibits Newtonian behaviour for n  1 and it resembles as a power-law model at higher shear rates. For n  1 it exhibits shear-thinning property, i. e., the apparent viscosity reduces with increasing shear rate. The equations governing the Fluid flow are solved with usual perturbation expansion by taking Weissenberg number i W as a perturbation parameter. The expressions for axial velocity, stream function and volume flow rate as function of pressure difference are derived. The effects of various pertinent parameters on variation of flux for a Carreau Fluid flow through an elastic tube along with peristalsis are calculated and interpreted through graphs. The pressure rise per wavelength and shear stress distribution for different values of physical parameters are calculated and presented. Trapping phenomenon is presented graphically to understand the physical behaviour of various parameters. The difference in flux variation is examined by two different models of Rubinow and Keller (1972) and Mazumdar (1992). It is observed that in elastic tubes, the flux of Carreau Fluid with peristalsis is more when the tension relation is a fifth degree polynomial as compared to exponential curve. When the power-law index n  1 or Weissenberg number 0 i W  and without peristalsis, the present results are similar to the observations of Rubinow and Keller (1972). Further, the relation between the function g (a) and radius of the elastic tube for both Newtonian, non-Newtonian cases are discussed graphically and these findings are identical with the investigations of Mazumdar (1992). The results observed for the present flow characteristics reports several interesting behaviours that warrant further study of physiological Fluids in elastic tubes with peristalsis.

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strs
Issue Info: 
  • Year: 

    2014
  • Volume: 

    10
  • Issue: 

    5
  • Pages: 

    335-344
Measures: 
  • Citations: 

    0
  • Views: 

    707
  • Downloads: 

    186
Abstract: 

Introduction: Use of an adhesive with a suitable composite resin is an important factor in tooth-colored restorations and increasing marginal sealing ability. The aim of this study was to evaluate the microleakage of various adhesives with composite resins using Fluid filtration and dye extraction techniques and assessment of the correlation between these two techniques.Materials and Methods: In this in vitro study, class II cavities were prepared on the proximal surfaces of 48 extracted sound human premolar teeth, measuring 1.5±0.5 mm in gingival width, 4 mm in occluso-gingival height and 1.3 of the inter-cuspal distance in width. The samples were divided into four groups (n=12). Group 1; OptiBond Solo Plus adhesive/Herculite XRV composite resin; Group 2: OptiBond Solo Plus adhesive/Master Dent composite resin; Group 3: Prime & Bond NT adhesive/Herculite XRV composite resin; Group 4: Prime & Bond NT adhesive/Master Dent composite resin. Microleakage was assessed primarily by Fluid filtration and then by dye extraction techniques. Data were analyzed with Kruskal-Wallis and Mann-Whitney tests, with Bonferroni correction and Spearman's rho correlation test at 95% confidence interval.Results: The minimum and maximum mean microleakage values were recorded in Fluid filtration and dye extraction techniques groups 1 and 4, respectively. There were significant differences between the experimental groups in microleakage with the two methods of leakage assessment (p value=0.001). Spearman's rho revealed a strongly direct correlation between the two methods (r=0.797, p value=0.000).Conclusion: In both methods of microleakage assessment, use of ethanol-based in comparison to acetone-based adhesive resulted in microleakage reduction. Application of light-cured composite resin contrary to self-cured composite resin with both types of adhesives increased marginal sealing ability.

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Issue Info: 
  • Year: 

    2019
  • Volume: 

    49
  • Issue: 

    1 (86)
  • Pages: 

    31-40
Measures: 
  • Citations: 

    0
  • Views: 

    311
  • Downloads: 

    254
Abstract: 

In the present study, the non-Newtonian Fluid flow with the temperature-dependent viscosity over a non-isothermal square cylinder is investigated. Carreau-Yasuda model is utilized to simulate the non-Newtonian properties of the Fluid. Non-Newtonian Lattice Boltzmann method, with local computing features, is used to numerical simulate of momentum and energy equations. Grid analysis and validation of results have been successfully completed. Simulations are accomplished for a wide range of parameters including Reynolds number 10< Re < 50, Non-Newtonian index 0. 3< n <1, and temperature-thinning index 0< b < 0. 5. Simulations show that the proposed method is able to predict the shear-and temperature-dependent properties of Carreau-Yasuda non-Newtonian Fluid flow. The results show that increasing of temperature-thinning index leads to reduction and increment of the drag coefficient and Nusselt number, respectively.

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Author(s): 

LASHCKARBOLOK M. | JABBARI E. | VUIK K.

Journal: 

SCIENTIA IRANICA

Issue Info: 
  • Year: 

    2014
  • Volume: 

    21
  • Issue: 

    1 (TRANSACTIONS A: CIVIL ENGINEERING)
  • Pages: 

    1-10
Measures: 
  • Citations: 

    0
  • Views: 

    57606
  • Downloads: 

    58867
Abstract: 

A simple node enrichment strategy using a gradient based error estimator is presented for the Collocated Discrete Least Squares (CDLS) meshless method. Also, a procedure is defined to distribute collocation points according to the field nodes position. Here, shape functions are constructed using Radial Point Interpolation Method (RPIM). As temporal discretization a first-order accurate scheme, named semi-incremental fractional step method is used. One of the advantages of this scheme is its capability to use large time step sizes for the solution of the governing equations on steady state problems. The capability of the presented strategy is shown by investigating Carreau-Yasuda Fluid flow model in solving lid-driven cavity flow problem with different curve fitting indices values.

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Journal: 

SCIENTIA IRANICA

Issue Info: 
  • Year: 

    2021
  • Volume: 

    28
  • Issue: 

    3 (Transactions F: Nanotechnology)
  • Pages: 

    1896-1907
Measures: 
  • Citations: 

    0
  • Views: 

    4406
  • Downloads: 

    1733
Abstract: 

This study carried out a numerical examination on the e ect of magnetohydrodynamic steady ow of Carreau uid on the transfer of thermal energy and mass species comprising nanoparticles with gyrotactic microorganisms through a heated disk. The roles of thermophoresis and Brownian motion were also considered in resolving this ow problem. Governing equations were solved using boundary layer theory emphasizing the coupled system of Partial Di erential Equations (PDEs) involving boundary conditions. The highly non-linear system of Ordinary Di erential Equations (ODEs) was generated using transformation approach. Due to the highly nonlinear form of the system of transformed equations, an approximate solution was presented which was evaluated using optimal homotopy method. Moreover, the e ects of prominent parameters on velocity, thermal energy, mass species, and motile density microorganisms were graphically examined. In addition, graphical observations regarding the mass species, thermal energy, and velocities were brie y discussed. It was estimated that in an intensi ed magnetic eld, the motion of uid particles and temperature of uid would decrease and increase, respectively.

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