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Total 1907 records

#### The interaction of a surface wave with waves on a diffuse interface

, Article Journal of Physical Oceanography ; Volume 34, Issue 1 , 2004 , Pages 204-213 ; 00223670 (ISSN) ; Seymour, B ; Sharif University of Technology
American Meteorological Society
2004

Abstract

A resonant interaction analysis is used to study the two-dimensional interaction of a surface wave with two waves on a diffuse interface in a stratified fluid. The fluid system is modeled as a combination of two homogenous finite-depth layer with a free surface, divided by a thin third layer. Two possibilities for the interaction are found: one between the surface wave and two first-mode interfacial waves and a second between the surface wave, a first-mode, and a second-mode interfacial wave. By taking the nondimensional density difference δ as a small perturbation parameter, the evolution equations of the interfacial waves are derived asymptotically. The analysis indicates that growth of...

#### An analytical expression for the fugacity coefficient of supercritical fluids

, Article High Temperatures - High Pressures ; Volume 35-36, Issue 5 , 2003 , Pages 529-539 ; 00181544 (ISSN) ; Madani, F ; Sharif University of Technology
Old City Publishing
2003

Abstract

An analytical expression for the fugacity coefficient of supercritical fluids has been derived from the equation of state. Here, the equation of state known as the linear isotherm regularity, LIR, is used to obtain this expression. We have inverted the LIR equation of state to obtain an appropriate expression for fugacity calculation. The inverted LIR (ILIR) works well at high pressures; but at high temperatures, Tr = T/Tc ≥2, ILIR is valid for the entire pressure range. ILIR is valid over a wide temperature range. Unlike LIR, ILIR is also valid at temperatures above twice the Boyle temperature. Like LIR, the inverted equation is a general equation of state which is valid for all types of...

#### Solubility calculation of oil-contaminated drill cuttings in supercritical carbon dioxide using statistical associating fluid theory (PC-SAFT)

, Article Chemical Engineering and Technology ; Volume 31, Issue 1 , 2008 , Pages 66-70 ; 09307516 (ISSN) ; Goodarznia, I ; Daneshi, R ; Sharif University of Technology
2008

Abstract

Supercritical fluid extraction is a new technology that could be effectively used to treat oil-contaminated drill cuttings generated during drilling for oil and gas. In this work, the solubility of oil-contaminated drill cuttings in supercritical carbon dioxide is obtained by an experimental flow type apparatus. The solubility was measured at 200 bar pressure, over a temperature range of 55-79.5°C. The measured solubility and experimental data for oil in drill cuttings were correlated using the PC-SAFT, PR and SRK EOS models, without any adjustable parameters. Average absolute derivations of less than 15.1 %, 98.7 %, and 99.3 % are achieved between predicted and experimental values for the...

#### Investigation of hydroelastic effect in analysis of high-speed craft

, Article Ships and Offshore Structures ; 2014 ; ISSN: 1754212X ; Seif, M. S ; Tabeshpur, M. R ; Yaakob, O ; Sharif University of Technology
Abstract

Hydroelastic effect in bottom slamming problem of high-speed craft is one of the most challenging issues in structural design. In this paper, numerical method is used to investigate the hydroelastic effect in bottom-water impact analysis of high-speed monohull craft. Slamming with two viewpoints of rigid and elastic structures (hydroelastic effect) is modelled by coupled computational fluid dynamic (CFD) and finite element method (FEM) techniques. The results showed that considering hydroelastic effect, especially in high-impact speed, reduces the structural deformations and stresses compared with quasi-statistic analysis. The effect of different parameters, such as boundary condition, plate...

#### Simulation of elasto-plastic deformations in composites by flow rules

, Article Indian Journal of Science and Technology ; Vol. 7, issue. 2 , 2014 , pp. 180-184 ; ISSN: 09746846 ; Fazaeli, D ; Daneshmand, S ; Shafaghatian, N ; Sharif University of Technology
Abstract

In this paper, a novel model is proposed to predict stress behavior in the fibrous polymer composites under an applied tensile axial loading. Tangential stress is obtained by simulating between polymeric matrix flow (polyester) and fluid flow. In the other words, creep behavior of the petrochemical material or polymeric resin (matrix) is modeled using fluid flow theory. Furthermore, behavior of the shear stress is predicted by suitable mathematical functions. Finally, important relation is extracted by combining the solid and fluid mechanics formulations

#### Multiscale probability distribution of pressure fluctuations in fluidized beds

, Article Journal of Statistical Mechanics: Theory and Experiment ; Volume 2012, Issue 7 , 2012 ; 17425468 (ISSN) ; Sahimi, M ; Rahimi Tabar, M. R ; Peinke, J ; Sharif University of Technology
2012

Abstract

Analysis of flow in fluidized beds, a common chemical reactor, is of much current interest due to its fundamental as well as industrial importance. Experimental data for the successive increments of the pressure fluctuations time series in a fluidized bed are analyzed by computing a multiscale probability density function (PDF) of the increments. The results demonstrate the evolution of the shape of the PDF from the short to long time scales. The deformation of the PDF across time scales may be modeled by the log-normal cascade model. The results are also in contrast to the previously proposed PDFs for the pressure fluctuations that include a Gaussian distribution and a PDF with a power-law...

#### Experimental investigation on thermal performance of closed loop pulsating heat pipes with soluble and insoluble binary working fluids and a proposed correlation

, Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; Volume 55, Issue 2 , February , 2019 , pp 375–384 ; 09477411 (ISSN) ; Kalan, K ; Shafii, M. B ; Sharif University of Technology
Springer Verlag
2018

Abstract

In this study, an experimental investigation was conducted from a thermal performance standpoint on closed-loop pulsating heat pipes (CLPHPs) with four different fluids and their water-based binary mixtures as working fluids with volume mixing ratios of 3:1, 1:1, and 1:3. Ethanol and acetone as two types of fluids that are soluble in water and, to unprecedentedly compare the behavior of insoluble mixtures with the soluble ones as the working fluids, toluene and hexane as two types that are insoluble in water were used. Additionally, to predict the thermal performance of the pure, soluble binary, and insoluble binary fluids simultaneously for the first time, a correlation was derived. © 2018...

#### Experimental investigation on thermal performance of closed loop pulsating heat pipes with soluble and insoluble binary working fluids and a proposed correlation

, Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; Volume 55, Issue 2 , 2019 , Pages 375-384 ; 09477411 (ISSN) ; Kalan, K ; Shafii, M. B ; Sharif University of Technology
Springer Verlag
2019

Abstract

In this study, an experimental investigation was conducted from a thermal performance standpoint on closed-loop pulsating heat pipes (CLPHPs) with four different fluids and their water-based binary mixtures as working fluids with volume mixing ratios of 3:1, 1:1, and 1:3. Ethanol and acetone as two types of fluids that are soluble in water and, to unprecedentedly compare the behavior of insoluble mixtures with the soluble ones as the working fluids, toluene and hexane as two types that are insoluble in water were used. Additionally, to predict the thermal performance of the pure, soluble binary, and insoluble binary fluids simultaneously for the first time, a correlation was derived. © 2018,...

#### A simple method of generating equations of state for hard sphere fluid

, Article Chemical Physics ; Volume 333, Issue 2-3 , 2007 , Pages 208-213 ; 03010104 (ISSN) ; Parsafar, G. A ; Sharif University of Technology
2007

Abstract

We present in this paper a simple method of obtaining various equations of state for hard sphere fluid in a simple unifying way. Using the first several virial coefficients of hard sphere fluid, we will guess equations of state by using the asymptotic expansion method. Among the equations of state obtained in this way are Percus-Yevick, Scaled Particle Theory, and Carnahan-Starling equations of state. Also by combining the Monte Carlo results on hard sphere fluid with the asymptotic expansion method many other equations of state for hard sphere fluid can be found where all of them give essentially similar results in the region of isotropic hard sphere liquid, i.e., up to η < 0.5, in which η...

#### The central roles of fractals, bifurcation, and Chaos in optimal fluid mixing

, Article American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED ; Volume 256 , 2000 , Pages 23-28 ; 08888116 (ISSN) ; Taeibi Rahni, M ; Sharif University of Technology
2000

Abstract

Mixing processes are widely used in industries and are being studied by a number of scientists; even though, a fundamental insight of the subject is still lacking. In this paper, some basic thoughts are set on the analogy between fluid mixing phenomena and fractal geometry/ properties/ processes. To this end, an unstable horseshoe pattern, which leads to a continuous extending boundary with maximum stretching and folding, is created and repeated. As a result, self-similarity property along with instability is imposed throughout the region, enhancing the fluid mixing. The procedures are verified computationally using the techniques of capacity and information dimensions, which are measured as...

#### Mesoscopic rheological modeling of drilling fluids: Effects of the electrolyte

, Article Journal of Petroleum Science and Engineering ; Volume 195 , 2020 ; Ramazani Saadatabadi, A ; Sharif University of Technology
Elsevier B.V
2020

Abstract

Drilling fluid is a complex fluid, including base fluid and other materials, carrying out the vital functions during drilling operation such as cutting transport and controlling formation pressure. In order to optimize performance of a drilling process, a reliable rheological model is required in the computation of fluid flow dynamics. Time-independent Generalized Newtonian formulation are the most common models for describing the rheological behavior of drilling fluids due to its simplicity and ease of use, in spite the fact that they are not able to predict the normal stresses and could not consider effects of active components on the rheological behavior of the drilling fluid and also...

#### Bioactive layer formation on alkaline-acid treated titanium in simulated body fluid

, Article Materials and Design ; Volume 28, Issue 7 , 2007 , Pages 2154-2159 ; 02613069 (ISSN) ; Afshar, A ; Chen, J ; Zhang, X ; Sharif University of Technology
Elsevier Ltd
2007

Abstract

Porous surface on titanium induces apatite formation in simulated body fluid (SBF). This work shows alkaline, acid and polishing treatment, which lead to create apatite coating. Specimens were soaked in 5 M solution of NaOH, 85% HCl-6% HF-9% H3PO4 and 2% HF-4% HNO3-94% H2O. Also many samples were polished with sandpaper. Specimens treated under the above conditions were soaked in simulated body fluid (SBF) for 5 days. Apatite formed within 5 days. The evaluation of Ca/P ratio of samples were made by EDAX analysis to get information of the Ca/P ratio. The values obtained for the apatite were in the range of 1.55, which is near to the stoichiometric value of apatite, for the sample, which was...

#### 3-D simulation of turbulent density

, Article 2006 2nd ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006, Miami, FL, 17 July 2006 through 20 July 2006 ; Volume 2006 , 2006 ; 0791837831 (ISBN); 9780791837832 (ISBN) ; Firoozabadi, B ; Afshin, H ; Ghasvari Jahromi, H ; Sharif University of Technology
2006

Abstract

Density current is a dense fluid, which is continuously released from a source and spreads down a sloping surface inside a lighter, motionless fluid. A low-Reynolds number k-ε model (Launder and Sharma, 1974) has been used to simulate the behavior of 3-D density currents. Density current with a uniform velocity and concentration enters the channel via a sluice gate into a lighter ambient fluid and moves forward down-slope. The model has been verified with the experimental data sets. Although the k-ε Launder and Sharma model is applied here to a conservative density current, it seems the analysis is valid in general for turbidity current laden with fine particles. Copyright © 2006 by ASME

#### Experimental and numerical hydrodynamic modeling of an underwater manipulator

, Article American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED ; Volume 256 , 2000 , Pages 291-296 ; 08888116 (ISSN) ; Tehranian, A ; Meghdari, A ; Sadeghipour, M. S ; Sharif University of Technology
2000

Abstract

This paper presents the kinematics and dynamic modeling of a three-link (3-DOF) underwater manipulator where the effects of hydrodynamic forces are investigated. In our investigation, drag and added mass coefficients are not considered as constants. In contrast, the drag coefficient is a variable with respect to all relative parameters. Experiments were conducted to validate the hydrodynamic model for a one degree-of-freedom manipulator up to a three degrees-of-freedom manipulator. Finally, the numerical and experimental results are compared and thoroughly discussed

#### Electroosmotic flow of power-law fluids with temperature dependent properties

, Article Journal of Non-Newtonian Fluid Mechanics ; Volume 185-186 , 2012 , Pages 49-57 ; 03770257 (ISSN) ; Saidi, M. H ; Sadeghi, A ; Sharif University of Technology
Elsevier
2012

Abstract

The influence of variable fluid properties on mixed electroosmotic and pressure driven flow of non-Newtonian fluids is investigated in this paper. The non-linear coupled energy and momentum equations are solved by means of an iterative numerical approach. The results reveal that the temperature dependent effects only become significant at very high values of the Debye-Hückel parameter in case of combined electroosmotic and pressure driven flow and could safely be neglected in other cases. It is observed that the physical properties variation lead to a higher mean velocity in case of pressure assisted flow and a lower mean velocity in case of pressure opposed flow. Furthermore, the...

#### Influence of monoethanolamine on thermal stability of starch in water based drilling fluid system

, Article Petroleum Exploration and Development ; Volume 45, Issue 1 , February , 2018 , Pages 167-171 ; 18763804 (ISSN) ; Ameri Shahrabi, M. J ; Heidari, H ; Valizadeh, M ; Sharif University of Technology
Elsevier B.V
2018

Abstract

To improve the thermal stability of starch in water-based drilling fluid, monoethanolamine (MEA) was added, and the effect was investigated by laboratory experiment. The experimental results show that the addition of monoethanolamine (MEA) increases the apparent viscosity, plastic viscosity, dynamic shear force, and static shear force of the drilling fluid, and reduces the filtration rate of drilling fluid and thickness of mud cake apparently. By creating hydrogen bonds with starch polymer, the monoethanolamine can prevent hydrolysis of starch at high temperature. Starch, as a natural polymer, is able to improve the rheological properties and reduce filtration of drilling fluid, but it works...

#### Recommendations on enhancing the efficiency of algebraic multigrid preconditioned GMRES in solving coupled fluid flow equations

, Article Numerical Heat Transfer, Part B: Fundamentals ; Volume 55, Issue 3 , 2009 , Pages 232-256 ; 10407790 (ISSN) ; Darbandi, M ; Sharif University of Technology
2009

Abstract

The algebraic multigrid (AMG) algorithm as a preconditioner to the Krylov subspace methods has drawn the attention of many researchers in solving fluid flow and heat transfer problems. However, the efficient employment of this solver needs experience, because users have to quantify several important parameters. In this work, we choose a hybrid finite-volume element method and quantify the optimum magnitudes for those parameters. To generalize our results, two sets of fluid flow governing equations, the thermobuoyant flow and confined diffusion flame, are studied and the optimum values are determined. The results indicate that the AMG can be very effective if a proper storage method is chosen...

#### Numerical investigation of blood flow. Part I: In microvessel bifurcations

, Article Communications in Nonlinear Science and Numerical Simulation ; Volume 13, Issue 8 , 2008 , Pages 1615-1626 ; 10075704 (ISSN) ; Mousavi, S. M ; Kolari, P ; Sharif University of Technology
2008

Abstract

In some diseases there is a focal pattern of velocity in regions of bifurcation, and thus the dynamics of bifurcation has been investigated in this work. A computational model of blood flow through branching geometries has been used to investigate the influence of bifurcation on blood flow distribution. The flow analysis applies the time-dependent, three-dimensional, incompressible Navier-Stokes equations for Newtonian fluids. The governing equations of mass and momentum conservation were solved to calculate the pressure and velocity fields. Movement of blood flow from an arteriole to a venule via a capillary has been simulated using the volume of fluid (VOF) method. The proposed simulation...

#### Treatment of oil-contaminated drill cuttings of South Pars gas field in Iran using supercritical carbon dioxide

, Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 30, Issue 5 , 2006 , Pages 607-611 ; 03601307 (ISSN) ; Esmaeilzadeh, F ; Sharif University of Technology
2006

Abstract

New treatment technologies are currently being investigated for the treatment of contaminated drilling waste mud with oil. Supercritical fluid extraction is a promising technology that could be effectively used to extract this contaminated drilling waste mud. In this work, one step extraction efficiency of supercritical carbon dioxide to drilling waste mud of South Pars gas field has been investigated at a range of temperatures (55 to 79.5 °C), and over a pressure range of 160 to 220 bar. Extraction efficiencies were calculated based on cuttings weight loss. Results show that approximately 28.45% of cuttings weight loss in one step extraction at a pressure of 200 bar and temperature of 60 °C...

#### Computer simulation of fluid motion in a porous bed using a volume of fluid method: Application in heap leaching

, Article Minerals Engineering ; Volume 19, Issue 10 , 2006 , Pages 1077-1083 ; 08926875 (ISSN) ; Jafari, A ; Yaghmaei, S ; Vossoughi, M ; Sarkomaa, P ; Sharif University of Technology
2006

Abstract

Heap leaching is a process extensively used by the mining industry to recover metals from low-grade ores and large quantities of submarginal material resources. Understanding flow through a packed particle bed is important to enhance the performance of heap leaching with respect to design and operating considerations. Complex fluid behavior in porous media, such as film flow, fragmentation, coalescence of droplets, and rivulet flow with or without meandering, has been widely observed in laboratory experiments. In this study, to provide detailed information of momentum and mass transfer phenomena in a granular bed direct numerical simulations (DNS) were performed. In this case the liquid-gas...