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**Search for:**flow-of-fluids

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Total 223 records

#### Three-dimensional structures in experimental density currents

, Article 2007 5th Joint ASME/JSME Fluids Engineering Summer Conference, FEDSM 2007, San Diego, CA, 30 July 2007 through 2 August 2007 ; Volume 1 SYMPOSIA, Issue PART A , March , 2007 , Pages 781-787 ; 0791842886 (ISBN); 9780791842881 (ISBN) ; Afshin, H ; Safaaee, E ; Sharif University of Technology
2007

Abstract

Density currents are continuous currents which move down-slope due to the fact that their density is greater than that of ambient water. The density difference is caused by temperature differences, chemical elements, dissolved materials, or suspended sediment. Many researchers have studied the density current structures, their complexities and uncertainties. However, there is not a detailed 3-D turbulent density current data set perfectly. In this work, the structure of 3-dimensional salt solution density currents is investigated. A laboratory channel was used to study the flow resulting from the release of salt solution into freshwater over an inclined bed. The experiments were conducted...

#### Darcy model for the study of the fluid flow and heat transfer around a cylinder embedded in porous media

, Article International Journal for Computational Methods in Engineering Science and Mechanics ; Volume 7, Issue 5 , 2006 , Pages 323-329 ; 15502287 (ISSN) ; Nouri Borujerdi, A ; Sharif University of Technology
Taylor and Francis Inc
2006

Abstract

Steady-state convective heat transfer around a circular cylinder embedded in porous media is studied in the range of low and moderate Peclet numbers less than 40. The cylinder is at constant temperature and the Darcy model is used for the analysis of fluid flow and heat transfer in porous media. The governing equations are discretised using finite volume approach based on staggered grids. The powerlaw scheme is used in the numerical solution and a SIMPLE-like algorithm is developed and used in the solution process. It is found that the numerical algorithm is sufficiently efficient in the range of Peclet numbers less than 40. Parametric studies are done for better understanding of the porous...

#### 3-D modeling of particle laden density current

, Article 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006, Chicago, IL, 5 November 2006 through 10 November 2006 ; 2006 ; 08888116 (ISSN); 0791837904 (ISBN); 9780791837900 (ISBN) ; Firoozabadi, B ; Ghasvari Jahromi, H ; Moosavi Hekmati, S. M. H ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2006

Abstract

The gravity currents on the inclined boundaries are formed when the inflow fluid has a density difference with the ambient fluid and a tangential component of gravity becomes the driving force. If the density difference arises from the suspension of particles, the currents are known as particle-driven density currents, in which the local density of the gravity current depends on the concentration of particles. A low Reynolds k-ε turbulence model is used to simulate three dimensional turbidity currents. Also a laboratory apparatus was built to study the 3D flow resulting from the release of particle laden density currents on a sloping surface in a channel of freshwater via a sluice gate and...

#### Oscillatory transient flow experiments and analysis in circular microchannels

, Article 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006, Chicago, IL, 5 November 2006 through 10 November 2006 ; 2006 ; 08888116 (ISSN); 0791837904 (ISBN); 9780791837900 (ISBN) ; Javadi, K ; Krägel, J ; Miller, R ; Kovalchuk, V. I ; Ferri, J. K ; Bastani, D ; Taeibi Rahni, M ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2006

Abstract

In this research purely oscillation fluid flow in two microtubes 150 and 250 μM(3.5 mm length) is studied using computational fluid dynamic (CFD) approach and utilizing a new experimental setup developed for dynamic interfacial tension measurement (capillary pressure technique) in the frequency range between 0.2 and 80 Hz. The experiments are done with pure water at a mean temperature of about 25 °C. The results of oscillatory conditions for microtubes of 0.5 mm in diameter have been compared with experimental results for several frequencies. The computational approach was validated by comparison with experimental data of the continuous constant flow through microtubes and also with...

#### Analysis of microchannel heat sink performance for electronics cooling based on thermodynamics

, Article 4th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM2006, Limerick, 19 June 2006 through 21 June 2006 ; Volume 2006 A , 2006 , Pages 355-362 ; 0791847608 (ISBN); 9780791847602 (ISBN) ; Saidi, M. H ; Zageneh Kazemi, P ; Sharif University of Technology
American Society of Mechanical Engineers
2006

Abstract

Present investigation analyzes the issue of entropy generation in a uniformly heated microchannel heat sink (MCHS). Analytical approach used to solve forced convection problem across MCHS, is porous medium model based on modified Darcy equation for fluid flow and two-equation model for heat transfer between solid and fluid phases. Furthermore, closed form solution of velocity distribution is employed to capture z-direction velocity gradient of flow, which plays a salient role on entropy generation through fluid flow. Analytical expressions for total and thermal entropy generation number (stems from heat transfer), and Bejan number are derived and cast into dimensionless form using velocity...

#### Compatible numerical schemes for coupled flow and transport in porous media

, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) ; Manzari, M. T ; Hannani, S. K ; Sharif University of Technology
American Society of Mechanical Engineers
2006

Abstract

In this paper, the compatibility of various combinations of numerical schemes for the solution of flow and transport equations in porous media is studied and the possible loss of accuracy and global mass conservation are investigated. Here, the flow equations are solved using three popular finite element methods including the Standard Galerkin (SG), Discontinuous Galerkin (DG) and Mixed Finite Element (MFE) methods among which only the DG method possesses the local conservation property. Besides, the transport of a scalar variable which is governed by a convection-diffusion equation is studied in conjunction with the flow equations. The transport equation is solved using both the Streamline...

#### Simulation of fluid flow through a granular bed

, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) ; Mousavi, S. M ; Sharif University of Technology
American Society of Mechanical Engineers
2006

Abstract

Numerical study of flow through random packing of non-overlapping spheres in a cylindrical geometry is investigated. Dimensionless pressure drop has been studied for a fluid through the porous media at moderate Reynolds numbers (based on pore permeability and interstitial fluid velocity), and numerical solution of Navier-Stokes equations in three dimensional porous packed bed illustrated in excellent agreement with those reported by Macdonald [1979] in the range of Reynolds number studied. The results compare to the previous work (Soleymani et al., 2002) show more accurate conclusion because the problem of channeling in a duct geometry. By injection of solute into the system, the...

#### Investigation of a two impinging-jets contacting device for liquid-liquid extraction processes

, Article Chemical Engineering Science ; Volume 61, Issue 12 , 2006 , Pages 3942-3950 ; 00092509 (ISSN) ; Ebrahimzadeh Zonouzian, S. A. R ; Molaei Dehkordi, A ; Sharif University of Technology
Elsevier Ltd
2006

Abstract

A two impinging-jets contacting device (TIJCD) for liquid-liquid extraction processes was proposed and tested through the standard test system recommended by the European Federation of Chemical Engineering (EFCE), toluene-acetone-water, as a typical example of liquid-liquid extraction processes. The results obtained for the overall volumetric mass transfer coefficient (capacity coefficient) were more than three times higher than those reported in the conventional contactors and in an air-driven two impinging-streams contactor. These experimental results clearly indicate the greater performance capability of TIJCD relative to those of conventional contactors. To have a perfect study on the...

#### Approach to analytic solution of navier-stokes equation utilizing adomian decomposition method, jet impinging flow application

, Article WSEAS Transactions on Mathematics ; Volume 5, Issue 5 , 2006 , Pages 507-514 ; 11092769 (ISSN) ; Taeibi Rahni, M ; Javadi, K. H ; Hosseinzadeh, S. F ; Sharif University of Technology
2006

Abstract

Adomian decomposition method was employed to obtain an approximate solution to two-dimensional and axisymmetric jet impinging flows in this work. Assumptions have been made to reduce the related full Navier-Stokes equations to a non-linear ordinary differential equation. A trial and error strategy has been used to obtain the constant coefficient in the approximated solution. Velocity Profiles, Shear stresses and displacement thickness were chosen to be compared with accurate numerical data. Sensitivity of the results to the number of terms have been discussed. The results showed for open boundary problems having at least one boundary condition at infinity, the applicable range of the...

#### On the stability of rotating pipes conveying fluid in annular liquid medium

, Article Journal of Sound and Vibration ; Volume 494 , 2021 ; 0022460X (ISSN) ; Dehghani Firouz-abadi, R ; Rahmanian, M ; Sharif University of Technology
Academic Press
2021

Abstract

This study provides a stability analysis of flexible rotating pipes taking into account the simultaneous effects of internal and external fluid loading. Using the Euler-Bernoulli beam assumptions, governing equations for flexural vibrations of rotating pipes are obtained. The internal flow characteristics and the double gyroscopic effect are taken into account when deriving the structural equations coupled with the internal flow. External fluid loading is determined by a special linearization of the Navier-Stokes equations. Considering the circular wall of the pipe as an impermeable boundary to the flow, fluid-induced forcing functions are obtained and then applied to the structural...

#### On the stability of rotating pipes conveying fluid in annular liquid medium

, Article Journal of Sound and Vibration ; Volume 494 , 2021 ; 0022460X (ISSN) ; Dehghani Firouz-abadi, R ; Rahmanian, M ; Sharif University of Technology
Academic Press
2021

Abstract

This study provides a stability analysis of flexible rotating pipes taking into account the simultaneous effects of internal and external fluid loading. Using the Euler-Bernoulli beam assumptions, governing equations for flexural vibrations of rotating pipes are obtained. The internal flow characteristics and the double gyroscopic effect are taken into account when deriving the structural equations coupled with the internal flow. External fluid loading is determined by a special linearization of the Navier-Stokes equations. Considering the circular wall of the pipe as an impermeable boundary to the flow, fluid-induced forcing functions are obtained and then applied to the structural...

#### Heat transfer and fluid flow in porous media with two equations Non-Darcian model

, Article 2005 ASME Fluids Engineering Division Summer Conference, Houston, TX, 19 June 2005 through 23 June 2005 ; Volume 2 , 2005 , Pages 637-640 ; 0791841987 (ISBN); 9780791841983 (ISBN) ; Nazari, M ; Sharif University of Technology
2005

Abstract

In the present study criterion for local thermal equilibrium assumption is studied. It concerns with the fluid flow and heat transfer between two parallel plates filled with a saturated porous medium under non-equilibrium condition. A two-equation model is utilized to represent the fluid and solid energy transport. Numerical Finite Volume Method has been developed for solving coupled energy equations and the Non-Darcian effects are considered for description of momentum equation. The effects of suitable non dimensional parameters as Peclet number and conductivity ratio has been studied thoroughly. A suitable non dimensional equation proposed in wide range of Peclet number and conductivity...

#### Analysis of micro channel heat sink performance

, Article 2005 SEM Annual Conference and Exposition on Experimental and Applied Mechanics, Portland, OR, 7 June 2005 through 9 June 2005 ; 2005 , Pages 1911-1918 ; 0912053909 (ISBN) ; Salehi, M ; Khiabani, R. H ; Sharif University of Technology
2005

Abstract

In the present research a numerical investigation has been made to evaluate the results of analytical approach in the analysis of micro channel heat sink (MCHS) which is increasingly used in the cooling of high heat dissipating electronic devices. In this regard the effects of geometrical and flow parameters affecting the absolute thermal resistance of MCHS have been analyzed. The effect of using different fluids in the value of the thermal resistance is considered as well. The accuracy of analytical method in predicting heat transfer and fluid flow regimes in micro channel is checked in comparison with numerical method. The effects of hydraulic and thermal entrance lengths of these systems...

#### Analysis and optimized design of a packaged liquid chiller (part I -Analytical modelling)

, Article 2005 ASME Summer Heat Transfer Conference, HT 2005, San Francisco, CA, 17 July 2005 through 22 July 2005 ; Volume 4 , 2005 , Pages 461-466 ; 0791847314 (ISBN); 9780791847312 (ISBN) ; Kargar, S ; Sharif University of Technology
2005

Abstract

The purpose of this work is to develop a physical simulation model for the purpose of studying the effect of various design parameters on the performance of a packaged liquid chiller. A computer model which simulates the steady-state cyclic performance of a vapor compression chiller is developed for the purpose of performing detailed physical design analysis of actual industrial chillers. The model can be used for optimizing design and for detailed energy efficiency analysis of packaged liquid chillers. The simulation model takes into account presence of all chiller components such as compressor, shell-and-tube condenser and evaporator heat exchangers, thermostatic expansion valve and...

#### Performance and stability enhancement of NASA Rotor 37 applying abradable coating

, Article ASME Turbo Expo 2005 - Gas Turbie Technology: Focus for the Future, Reno-Tahoe, NV, 6 June 2005 through 9 June 2005 ; Volume 6 PART A , 2005 , Pages 93-102 ; Farhanieh, B ; Ghorbanian, K ; Teixeira, J. A ; Ivey, P. C ; ASME International Gas Turbine Institute ; Sharif University of Technology
2005

Abstract

Improvements in sealing mechanism between the rotating and the stationary parts of a rurbomachine can extensively reduce the endwall leakage flow. In this regard, abradable seals are incorporated into compressor and turbine blade-tip region. In a gas turbine, equipped with abradable seals, tip of the rotor blade is designed to cut into the material coating of the casing and to form a close fitted circumferential groove for the movement of the blade tip. As a result, the resistance to the leakage flow in the tip gap region increases due to smaller tip clearances (available without any rub-induced damages). Minimizing the tip clearance size can lead to an increase in performance and stability....

#### Analysis of fluid flow and heat transfer in microchannels using combined pressure gradient and electroosmotic pumping

, Article 3rd International Conference on Microchannels and Minichannels, ICMM2005, Toronto, ON, 13 June 2005 through 15 June 2005 ; Volume PART A , 2005 , Pages 503-510 ; 0791841855 (ISBN) ; Zade, A. Q ; Manzari, M. T ; Sharif University of Technology
2005

Abstract

A numerical model has been developed for studying the flow and heat transfer characteristics of single phase liquid flow through a microchannel. In this work the heat transfer characteristics of pressure driven and electroosmotic flow through microchannels have been studied. The governing equations are the Poisson-Boltzmann and Navier-Stokes equations which have been solved numerically using the standard Galerkin and the Mixed 4-1 finite element methods, respectively. Finally the energy equation is solved numerically using the Stream-wise Upwind Petrov Galerkin (SUPG) method. Two dimensional Poisson-Boltzmann equation was first solved to find the electric potential field and net charge...

#### A mass conservative scheme for simulating shallow flows over variable topographies using unstructured grid

, Article Advances in Water Resources ; Volume 28, Issue 5 , 2005 , Pages 523-539 ; 03091708 (ISSN) ; Le Roux, D. Y ; Tajrishi, M ; Mazaheri, K ; Sharif University of Technology
2005

Abstract

Most available numerical methods face problems, in the presence of variable topographies, due to the imbalance between the source and flux terms. Treatments for this problem generally work well for structured grids, but most of them are not directly applicable for unstructured grids. On the other hand, despite of their good performance for discontinuous flows, most available numerical schemes (such as HLL flux and ENO schemes) induce a high level of numerical diffusion in simulating recirculating flows. A numerical method for simulating shallow recirculating flows over a variable topography on unstructured grids is presented. This mass conservative approach can simulate different flow...

#### Saffman-Taylor instability in yield stress fluids

, Article Journal of Physics Condensed Matter ; Volume 17, Issue 14 , 2005 , Pages S1209-S1218 ; 09538984 (ISSN) ; Lindner, A ; Rouhani, S ; Bonn, D ; Sharif University of Technology
Institute of Physics Publishing
2005

Abstract

Pushing a fluid with a less viscous one gives rise to the well known Saffman-Taylor instability. This instability is important in a wide variety of applications involving strongly non-Newtonian fluids that often exhibit a yield stress. Here we investigate the Saffmann-Taylor instability in this type of fluid, in longitudinal flows in Hele-Shaw cells. In particular, we study Darcy's law for yield stress fluids. The dispersion equation for the flow is similar to the equations obtained for ordinary viscous fluids but the viscous terms in the dimensionless numbers conditioning the instability now contain the yield stress. This also has repercussions on the wavelength of the instability as it...

#### Fractal flow of inhomogeneous fluids over smooth inclined surfaces and determination of their fractal dimensions and universality classes

, Article Journal of Physics Condensed Matter ; Volume 17, Issue 14 , 2005 , Pages S1219-S1227 ; 09538984 (ISSN) ; Ghane Motlagh, B ; Baradaran, S ; Shekarian, E ; Rouhani, S ; Sharif University of Technology
2005

Abstract

Patterns formed by the flow of an inhomogeneous fluid (suspension) over a smooth inclined surface were studied. It was observed that fractal patterns are formed. There exists a threshold angle for the inclination above which global fractal patterns are formed. This angle depends on the particle size of the suspension. We observed that there are two fractal dimensions for these patterns, depending on the area from which the pattern is extracted. If the pattern is taken from the top which only consists of the beginning steps of the pattern forming, one finds two fractal dimensions, i.e. 1.35-1.45 and 1.6-1.7, in which the first one is dominant. And if the entire pattern is taken, then fractal...

#### A finite-volume-based lattice-Boltzmann method to simulate buoyant flow

, Article 43rd AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, 10 January 2005 through 13 January 2005 ; 2005 , Pages 2675-2684 ; Niavarani Kheiri, A ; Schneider, G. E ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2005

Abstract

Despite great advancement in the lattice Boltzmann method and its application in fluid flow problems, there are still major restrictions in treating either the solution domains with complex boundaries or buoyant flow problems. The past experience shows that the heat equation is a source for instabilities which jeopardizes the stable solution of the lattice Boltzmann method in solving fluid flow problems with heat transfer. The instabilities Increase with increasing buoyant force strength. In this work, we suggest a new approach to overcome the restrictions through implementing the advantages of finite volume method in LBM. In this regard, the lattice Boltzznann equation is incorporated with...