Search for: non-newtonian-fluids
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    DPD simulation of non-Newtonian electroosmotic fluid flow in nanochannel

    , Article Molecular Simulation ; Volume 44, Issue 17 , 2018 , Pages 1444-1453 ; 08927022 (ISSN) Jafari, S ; Zakeri, R ; Darbandi, M ; Sharif University of Technology
    Taylor and Francis Ltd  2018
    We use the dissipative particle dynamics (DPD) method to simulate the non-Newtonian electroosmotic flow (EOF) through nanochannels. Contrary to a large amount of past computational efforts dedicated to the study of EOF profile, this work pays attention to the EOF of non-Newtonian fluids, which has been rarely touched in past publications. Practically, there are many MEMS/NEMS devices, in which the EOF behaviour should be treated assuming both non-continuum and non-Newtonian conditions. Therefore, our concern in this work is to simulate the EOF through nanochannels considering both non-Newtonian fluid properties and non-continuum flow conditions. We have chosen DPD as our working tool because... 

    Numerical Simulation of Heat Transfer on Topographically Structured Surfaces

    , M.Sc. Thesis Sharif University of Technology Javanbakht, Mohammad Hossein (Author) ; Moosavi, Ali (Supervisor)
    Numerous three-dimensional models of laminar flow and heat transfer in rough microchannels are developed and analyzed numerically to compare the effect of roughness elements on the thermal and hydrodynamic characteristics. In these models, the rough surfaces are configured with rectangular, triangular and sinusoidal roughness elements. Here, the effects of the roughness height, roughness element width, roughness element pitch, channel separation, Reynolds number and both Newtonian and non-Newtonian fluid on pressure drop and heat transfer in rough microchannels are all investigated and discussed.H2 thermal boundary condition is considered for all peripheral walls and power law model also is... 

    Modeling of Flow of Nano-filled Viscoelastic Fluids and its Application in Rheometry

    , M.Sc. Thesis Sharif University of Technology Kamyabi, Mohammad Mahdi (Author) ; Ramazani Saadatabadi, Ahmad (Supervisor)
    Despite of passing many years from invention of Computational Fluid Dynamics (CFD), simulation of the fluid-solid interfaces and free surfaces are still completely challenging and progressive problems. In addition knowing and understanding nanotechnology huge applications,modeling of nano-fluids have been became a priority for researchers. Adding importance of Non-Newtonian fluids (especially polymeric solutions) to this two subjects, triangle topics of this research becomes vivid. In this research tried to consider and examine behavior of Newtonian,Generalized-Newtonian, Viscoelastic and nano-filled viscoelastic fluids in one and two phase mediums. we followed mesh free methods which are... 

    Experimental Study of Spray Pattern of Two Impinging Jets of Non-Newtonian Gel Fluid Containing Aluminum Nanoparticles

    , M.Sc. Thesis Sharif University of Technology Jafari, Maryam (Author) ; Kebriaee, Azadeh (Supervisor)
    In most of the studies conducted on the physics of the outflow from impinging jet injectors, Newtonian fluids have been used for their research and experiments. These studies have investigated the effect of factors such as geometrical parameters of the injector and physical properties of the fluid on different regimes resulting from the impact of the jet stream; Unfortunately, very few studies have been conducted on how to form spray and atomization in gel non-Newtonian fluids containing nanoparticles to investigate the above factors when using impinging jet injectors. Furthermore, although the addition of nanoparticles has advantages for better combustion, there are still problems in... 

    Introducing a rheology model for non-newtonian drilling fluids

    , Article Geofluids ; Volume 2021 , 2021 ; 14688115 (ISSN) Rashidi, M ; Sedaghat, A ; Misbah, B ; Sabati, M ; Vaidyan, K ; Mostafaeipour, A ; Dehshiri, S. S. H ; Almutairi, K ; Issakhov, A ; Sharif University of Technology
    Hindawi Limited  2021
    An API standard drilling fluid was investigated from laminar to turbulent flow conditions using an in-house-built viscometer at speeds from 200 to 1600 RPM. A power-based method was applied to obtain the apparent viscosity and the shear stress of the water-based drilling mud (WBM) in the annulus of the viscometer. Then, a MATLAB optimization program was developed to obtain model parameters for five rheology models integrated in a generalized Herschel-Bulkley-Extended (HBE) model and two widely used 4-parameter models in drilling industry. It is found that the Bingham, Cross, and HBE rheology models have precisely matched the WBM measurements in the viscometer. A generalized Reynolds number... 

    Drag Reduction Using Geometrically Structured Surfaces for Non-newtonian Multi-phase Fluids

    , M.Sc. Thesis Sharif University of Technology Javaherchian, Javaneh (Author) ; Moosavi, Ali (Supervisor)
    With the advancement of the industry, microscale devices use due to its unique characteristics. On the other hand, it is essential to find ways to reduce drag inside microchannels because of The importance of energy. One of the methods is to optimize the contact surface using structured geometric surfaces. These hydrophobic surfaces reduce drag by trapping the air in roughness and creating a two-phase flow. The purpose of this project is to reduce the drag within the microchannel using structured geometric surfaces for non-Newtonian and multiphase flows. In most previous studies, with simplification, Newtonian and two-phase flows have been investigated. While most industrial fluids show... 

    Experimental and Theoretical Investigation of Ascending Accelerated Motion of Single Bubble in Quiescent Newtonian and Non-newtonian Liquids

    , M.Sc. Thesis Sharif University of Technology Shahsavari, Mona (Author) ; Firoozabadi, Bahar (Supervisor) ; Afshin, Hossein (Supervisor)
    The gas-liquid interaction is one of the most important and common phenomenons in chemical, biochemical and mineral industries which is generally observed as liquid in a gas stream (droplet) or gas in a liquid stream (bubble). Although bubbles produced in the industrial applications are in the form of a group of bubbles, understanding the hydrodynamics of a single bubble in a quiescent liquid provides a starting point for studying bubble groups. It should be noted that changes in the velocity and drag coefficient of the bubbles in various fluids are essential parameters for designing gas-liquid systems. In the present research, in order to examine the effect of system parameters and... 

    Simulation of Non-newtonian Flow of Drilling Fluid Around the Drill String with the Olga Software

    , M.Sc. Thesis Sharif University of Technology Sadri, Avazdordi (Author) ; Jamshidi, Saeed (Supervisor)
    Because of the importance of simulations in the oil industry, there are different software applications designed for this purpose. The purpose of the simulation in the oil industry is to reduce operational errors during the operation and to achieve the most ideal mode of operation. However, in the simulation of multiphase fluid flow because of the special circumstance, simulation plays an important role in the oil industry. OLGA multiphase flow simulation software is a strong simulation software for water, oil, Gas wells, wellhead facilities, refineries and pipelines and it is capable of simulating pipelines under various dynamic conditions. Simulation of drilling hydraulic parameters is... 

    Experimental Study of a Single Bubble Formation and Its Deformation in Shear-thinning Fluids

    , M.Sc. Thesis Sharif University of Technology Esfidani, Mohammad Taghi (Author) ; Afshin, Hossein (Supervisor) ; Firoozabadi, Bahar (Supervisor)
    Bubble formation and bubble rising are widely used in many industrial processes such as bubble columns, extraction, fermentation, foaming and polymerization. Although many of these processes are faced with a series of bubbles, this study may help us better understand the hydrodynamics of single bubble formation and bubble rising and provides a deep insight into the modeling of a series of bubbles. Bubble velocity and drag coefficient in various fluids are the major parameters for designing the liquid-gas systems. These parameters are a function of the bubble size. In this study, single bubble formation is theoretically modelled in order to predict the size of the bubble at the moment of... 

    Influence of Geometrical Parameters on Hemodynamics of Blood Flow in Coronary Artery Bypass Graft by FSI Numerical Method

    , M.Sc. Thesis Sharif University of Technology Saffari, Ali (Author) ; Halali, Mohammad (Supervisor) ; Hossein Ahmadi, Zargham (Supervisor)
    In this study, the simulation of blood flow through a stenosed coronary artery and a bypass graft are discussed using fluid-structure interaction numerical method. Effects of the geometrical parameters of CABG surgery on hemodynamics have been studied. Investigated hemodynamic variables include shear stress on the vessel wall, the velocity profile in high-risk areas and the pathlines. Lower than 0.5 Pa shear stress on intimal layer of arteries causes the formation of plaque on the wall. Angle of 30 degrees and diameter ratio of bypass to host artery of 1:1 are proposed as the optimum geometry. The distance of the anastomosis from the site of occlusion has no effect on surgery. Also,... 

    Fabrication of Superhydrophobic Surfaces to Decrease Pressure Drop through the Galvanized Pipe and Study about Feasibility of the Fabricated Surface to Use for Non-newtonian Fluid

    , M.Sc. Thesis Sharif University of Technology Pakzad, Hossein (Author) ; Mousavi, Ali (Supervisor) ; Nouri boroojerdi, Ali (Supervisor)
    Nowdays, one of the most important concerns for scientists is increasing CO2 emmisions and global warming. To overcome this problem, a large number of studies have been carried out to improve energy system performance and reducing the overall energy consumption. One solution to this problem is using the superhydrophobic surfaces with contact angle larger than 150°.In this study, we try to reduce the pressure drop through the galvanized pipes. So, by reducing the pressure drop, power required for pumps can be reduced. To this end, two different coatings by silica nano-particles which were modified with first hydrophobic agent are used. In first coating which is named as PS coating, stearic... 

    Dynamics and Heat transfer of Two-phase Non-Newtonian Fluids in Superhydrophobic Channels

    , M.Sc. Thesis Sharif University of Technology Shahsavari, Arghavan (Author) ; Moosavi, Ali (Supervisor)
    When the fluid passes through the microchannel, some energy is lost due to drag force and pressure drop. One of the methods used in the last few decades to optimize energy consumption is creating superhydrophobic surfaces in microchannels. These surfaces, with their features such as increasing the contact angle and reducing the contact angle hysteresis, can reduce energy loss, which is due to the presence of unevenness on the surface, and by trapping air and creating a two-phase flow, they reduce the drag force. On the other hand, the air trapped inside these irregularities will also affect the heat transfer of the passing fluid in the microchannel, which by creating resistance in the... 

    Mechanical Properties of Lubricants in Nano Powders Compaction Process Using Molecular Dynamics and Continuum Mechanics Methods

    , M.Sc. Thesis Sharif University of Technology Palahang, Pezhman (Author) ; Khoei, Amir Reza (Supervisor)
    The primary objective of this study entails the examination of the impact of lubricants intended for implementation in the compaction process of nano-powders, intending to mitigate friction at the nano scale during compaction. Molecular dynamics modeling is employed to scrutinize this phenomenon and derive the friction parameters within the framework of equations derived from continuum mechanics, based on data acquired from the nanoscale investigations. The manufacturing procedure of metallic components from metal powder compaction necessitates the application of immense pressures, thereby engendering notable friction between the powder particles and the confines of the mold. Consequently,... 

    Saffman-Taylor instability in yield stress fluids

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

    A depthwise averaging solution for cross-stream diffusion in a Y-micromixer by considering thick electrical double layers and nonlinear rheology

    , Article Microfluidics and Nanofluidics ; Volume 19, Issue 6 , 2015 , Pages 1297-1308 ; 16134982 (ISSN) Ahmadian Yazdi, A ; Sadeghi, A ; Saidi, M. H ; Sharif University of Technology
    Springer Verlag  2015
    Both nonlinear rheology and finite EDL thickness effects on the mixing process in an electroosmotically actuated Y-sensor are being investigated in this paper, utilizing a depthwise averaging method based on the Taylor dispersion theory. The fluid rheological behavior is assumed to obey the power-law viscosity model. Analytical solutions are obtained assuming a large channel width to depth ratio for which a 1-D profile can efficiently describe the velocity distribution. Full numerical simulations are also performed to determine the applicability range of the analytical model, revealing that it is able to provide accurate results for channel aspect ratios of ten and higher and quite... 

    Unsteady natural convection in a differentially heated rectangular enclosure possessing sinusoidal corrugated side walls loaded with power law non-newtonian fluid

    , Article Fluid Dynamics ; Volume 54, Issue 2 , 2019 , Pages 159-176 ; 00154628 (ISSN) Salehpour, A ; Abdolahi Sadatlu, M. A ; Sojoudi, A ; Sharif University of Technology
    Pleiades Publishing  2019
    This research is a numerical analysis exhaustively investigating two-dimensional (2D) transient convective heat transfer in a differentially heated rectangle, possessing sinusoidal corrugated side walls at constant temperatures. The quadrilateral space is filled with a power-law non-Newtonian fluid, plus the right and left walls are uniformly cooled and heated, respectively. The top and bottom walls are retained as adiabatic and the side walls are recast exploiting sinusoidal corrugated shape. The governing equations of the problem are solved using the finite volume method. The evaluation of fluid flow and heat transfer is conducted in such a manner that the power law index n varies from 0.6... 

    Modelling of power-law fluid flow through porous media using smoothed particle hydrodynamics

    , Article Transport in Porous Media ; Volume 74, Issue 3 , 2008 , Pages 331-346 ; 01693913 (ISSN) Vakilha, M ; Manzari, M. T ; Sharif University of Technology
    The flow of non-Newtonian fluids through two-dimensional porous media is analyzed at the pore scale using the smoothed particle hydrodynamics (SPH) method. A fully explicit projection method is used to simulate incompressible flow. This study focuses on a shear-thinning power-law model (n < 1), though the method is sufficiently general to include other stress-shear rate relationships. The capabilities of the proposed method are demonstrated by analyzing a Poiseuille problem at low Reynolds numbers. Two test cases are also solved to evaluate validity of Darcy's law for power-law fluids and to investigate the effect of anisotropy at the pore scale. Results show that the proposed algorithm can... 

    Numerical Investigation on Oil/Water Separation through Coalescence in Membrane Pores

    , M.Sc. Thesis Sharif University of Technology Rashidi, Hojat (Author) ; Moosavi, Ali (Supervisor)
    Oil/water separation is an important field, not only for scientific research, but also for environmental, economic, and social issues. On the one hand, oily wastewater, resulting from industries such as steel, aluminum, food, textile, leather, petrochemical and metal finishing, has become the most common pollutant all over the world. On the other hand, frequent oil spill accidents are of great concern since the discharge can lead not only to serious environmental pollution, but also a great loss of energy.
    In crude oil removing water is necessary due to reducing corrosion, increasing thermal values of fuels obtained from crude oil, preventing catalists from destruction by water and... 

    Design and Development of Non-Newtonian Droplet-based Logic Microfluidics Using Passive Method

    , Ph.D. Dissertation Sharif University of Technology Asghari, Elmira (Author) ; Moosavi, Ali (Supervisor) ; Kazemzadeh Hannani, Siamak (Supervisor)
    Droplet-based microfluidic logic gates have many applications in diagnostic tests and biosciences due to their automation and cascading ability. Although most biological fluids, such as blood, exhibit non-Newtonian properties, all previous studies in this field have been with Newtonian fluids. Additionally, none of the previous work has studied the functional area of logic gates. In the present work, AND-OR logic gate with power-law fluid is considered. The effect of important parameters such as non-Newtonian fluid properties, droplet length, capillary number, and geometrical properties of the microfluidic system on the operating region of the system has been investigated. The results show... 

    Thermal transport characteristics of non-newtonian electroosmotic flow in a slit microchannel

    , Article ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2011, 19 June 2011 through 22 June 2011 ; Volume 1 , June , 2011 , Pages 169-176 ; 9780791844632 (ISBN) Babaie, A ; Sadeghi, A ; Saidi, M. H ; Sharif University of Technology
    Electroosmosis has many applications in fluid delivery at microscale, sample collection, detection, mixing and separation of various biological and chemical species. In biological applications, most fluids are known to be non-Newtonian. Therefore, the study of thermal features of non-Newtonian electroosmotic flow is of great importance for scientific communities. In the present work, the fully developed electroosmotic flow of power-law fluids in a slit microchannel is investigated. The related equations are transformed into non-dimensional forms and necessary changes are made to adapt them for non-Newtonian fluids of power-law model. Results show that depending on different flow parameters...