Open Access. Powered by Scholars. Published by Universities.®
Materials Science and Engineering Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Keyword
-
- Molecular Dynamics Simulations (9)
- Yield Stress (8)
- Deformation (7)
- Glasses (5)
- Metallic Glasses (5)
-
- Temperature (3)
- 3D-printing (2)
- Carbon Nanotubes (2)
- Metallic glasses (2)
- Microfiltration (2)
- Molecular Dynamics Simulation (2)
- Molecular dynamics simulations (2)
- Multiphase Flows (2)
- Periodic Deformation (2)
- Strain Amplitude (2)
- Thermal Treatment (2)
- Volume of Fluid Method (2)
- 3-D Printing (1)
- Additive Manufacturing (1)
- Aerospace systems (1)
- Air pollution (1)
- Aircraft (1)
- Airfoil (1)
- Alignment (1)
- Angiographic image processing (1)
- Aptamer (1)
- Artificial Intelligence (1)
- Bacterial Degradation with Nanostructured Solids (1)
- Batteries (1)
- Biomimetic (1)
- Publication Year
- Publication
- Publication Type
Articles 61 - 90 of 116
Full-Text Articles in Materials Science and Engineering
The Effect Of A Reversible Shear Transformation On Plastic Deformation Of An Amorphous Solid, Nikolai V. Priezjev
The Effect Of A Reversible Shear Transformation On Plastic Deformation Of An Amorphous Solid, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
Molecular dynamics simulations are performed to investigate the plastic response of a model glass to a local shear transformation in a quiescent system. The deformation of the material is induced by a spherical inclusion that is gradually strained into an ellipsoid of the same volume and then reverted back into the sphere. We show that the number of cage-breaking events increases with increasing strain amplitude of the shear transformation. The results of numerical simulations indicate that the density of cage jumps is larger in the cases of weak damping or slow shear transformation. Remarkably, we also found that, for a …
Diffusion Of A Janus Nanoparticle In An Explicit Solvent: A Molecular Dynamics Simulation Study, Ali Kharazmi, Nikolai V. Priezjev
Diffusion Of A Janus Nanoparticle In An Explicit Solvent: A Molecular Dynamics Simulation Study, Ali Kharazmi, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
Molecular dynamics simulations are carried out to study the translational and rotational diffusion of a single Janus particle immersed in a dense Lennard-Jones fluid. We consider a spherical particle with two hemispheres of different wettabilities. The analysis of the particle dynamics is based on the time-dependent orientation tensor, particle displacement, as well as the translational and angular velocity autocorrelation functions. It was found that both translational and rotational diffusion coefficients increase with decreasing surface energy at the nonwetting hemisphere, provided that the wettability of the other hemisphere remains unchanged. We also observed that in contrast to homogeneous particles, the nonwetting …
Plastic Deformation Of A Model Glass Induced By A Local Shear Transformation, Nikolai V. Priezjev
Plastic Deformation Of A Model Glass Induced By A Local Shear Transformation, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The effect of a local shear transformation on plastic deformation of a three-dimensional amorphous solid is studied using molecular dynamics simulations. We consider a spherical inclusion, which is gradually transformed into an ellipsoid of the same volume and then converted back into the sphere. It is shown that at sufficiently large strain amplitudes, the deformation of the material involves localized plastic events that are identified based on the relative displacement of atoms before and after the shear transformation. We find that the density profiles of cage jumps decay away from the inclusion, which correlates well with the radial dependence of …
Computational Fluid Dynamics Simulation Of Intracranial Aneurysms - Comparing Size And Shape, Zifeng Yang, Hongtao Yu, George P. Huang, Ryan Schwieterman, Bryan Ludwig
Computational Fluid Dynamics Simulation Of Intracranial Aneurysms - Comparing Size And Shape, Zifeng Yang, Hongtao Yu, George P. Huang, Ryan Schwieterman, Bryan Ludwig
Mechanical and Materials Engineering Faculty Publications
Objective: To study the hemodynamics of an anatomic internal carotid artery aneurysm derived from a patient-specific model and then manipulate into two phantom morphologies: one growing uniformly by size and the other changing shape unevenly. Methods: The computational model of the saccular, internal carotid artery, aneurysm was constructed from 3D rotational, digitally subtracted, catheter angiography images. Computational fluid dynamics simulations were performed under pulsatile cardiac flow conditions. Velocity vectors, streamlines, pressure, and wall shear stress (WSS) and its variance distributions were quantitatively visualized. Results: The maximum pressure and WSS from the time-averaged distribution on the inside saccular surface of the …
Multifunctional Nanomaterials For Biomedical Engineering: Unique Properties, Fabrications, And Diverse Applications, Jen-Jie Chieh, Sharmila M. Mukhopadhyay, Yali Cui
Multifunctional Nanomaterials For Biomedical Engineering: Unique Properties, Fabrications, And Diverse Applications, Jen-Jie Chieh, Sharmila M. Mukhopadhyay, Yali Cui
Mechanical and Materials Engineering Faculty Publications
Nanomaterials possess many unique properties useful for biomedical applications ranging from preoperative and intraoperative imaging to coatings, assays, and cell scaffolds. Their popularity and production value are full of competitiveness. Their related methodologies and instruments are also created or emphasized as the mainstream. Since multifunctional nanomaterials attract interests and attention of researchers, engineers, and businessmen in biomedical engineering, this journal is set up to publish a special issue devoted to this topic. The result is a collection of five original research articles, whose authors belong to academic or research institutions of five different countries from Asia, Europe, and America. Papers …
Finite Element Analysis Of System-Level Electronic Packages For Space Applications, Adrien Lambert, Ahsan Mian, Justin Hogan, Todd Kaiser, Brock Lameres
Finite Element Analysis Of System-Level Electronic Packages For Space Applications, Adrien Lambert, Ahsan Mian, Justin Hogan, Todd Kaiser, Brock Lameres
Mechanical and Materials Engineering Faculty Publications
Thermal analysis was required in order to aid in the design and testing of a radiation tolerant computing (RTC) system using a radiation sensor. During development of the system, different test beds were employed in order to characterize the radiation sensor and its supporting electronic systems. The most common preliminary tests are high altitude balloon tests which allow the sensor to experience cosmic radiation at high altitudes, consistent with space flight operations. In this study, finite element analysis (FEA) was used to evaluate primary system architecture, system support structures, and the flight payload in order to determine if the system …
Dynamical Heterogeneity In Periodically Deformed Polymer Glasses, Nikolai V. Priezjev
Dynamical Heterogeneity In Periodically Deformed Polymer Glasses, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The dynamics of structural relaxation in a model polymer glass subject to spatially homogeneous, time-periodic shear deformation is investigated using molecular dynamics simulations. We study a coarse-grained bead-spring model of short polymer chains below the glass transition temperature. It is found that at small strain amplitudes, the segmental dynamics is nearly reversible over about 104 cycles, while at strain amplitudes above a few percent, polymer chains become fully relaxed after a hundred cycles. At the critical strain amplitude, the transition from slow to fast relaxation dynamics is associated with the largest number of dynamically correlated monomers as indicated by the …
Oil Droplet Behavior At A Pore Entrance In The Presence Of Crossflow: Implications For Microfiltration Of Oil-Water Dispersions, Nikolai V. Priezjev, Tohid Darvishzadeh, Volodymyr V. Taravara
Oil Droplet Behavior At A Pore Entrance In The Presence Of Crossflow: Implications For Microfiltration Of Oil-Water Dispersions, Nikolai V. Priezjev, Tohid Darvishzadeh, Volodymyr V. Taravara
Mechanical and Materials Engineering Faculty Publications
The behavior of an oil droplet pinned at the entrance of a micropore and subject to clossflow-induced shear is investigated numerically by solving the Navier-Stokes equation. We found that in the absence of crossflow, the critical transmembrane pressure required to force the droplet into the pore is in excellent agreement with a theoretical prediction based on the Young-Laplace equation. With increasing shear rate, the critical pressure of permeation increases, and at sufficiently high shear rates the oil droplet breaks up into two segments. The results of numerical simulations indicate that droplet breakup at the pore entrance is facilitated at lower …
Heterogeneous Relaxation Dynamics In Amorphous Materials Under Cyclic Loading, Nikolai V. Priezjev
Heterogeneous Relaxation Dynamics In Amorphous Materials Under Cyclic Loading, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
Molecular dynamics simulations are performed to investigate heterogeneous dynamics in amorphous glassy materials under oscillatory shear strain. We consider three-dimensional binary Lennard-Jones mixture well below the glass transition temperature. The structural relaxation and dynamical heterogeneity are quantified by means of the self-overlap order parameter and the dynamic susceptibility. We found that at sufficiently small strain amplitudes, the mean square displacement exhibits a broad subdiffusive plateau and the system undergoes nearly reversible deformation over about 104 cycles. Upon increasing strain amplitude, the transition to the diffusive regime occurs at shorter time intervals and the relaxation process involves intermittent bursts of large …
Anisotropic Compositional Expansion And Chemical Potential For Amorphous Lithiated Silicon Under Stress Tensor, Valery I. Levitas, Hamed Attariani
Anisotropic Compositional Expansion And Chemical Potential For Amorphous Lithiated Silicon Under Stress Tensor, Valery I. Levitas, Hamed Attariani
Mechanical and Materials Engineering Faculty Publications
Si is a promising anode material for Li-ion batteries, since it absorbs large amounts of Li. However, insertion of Li leads to 334% of volumetric expansion, huge stresses, and fracture; it can be suppressed by utilizing nanoscale anode structures. Continuum approaches to stress relaxation in LixSi, based on plasticity theory, are unrealistic, because the yield strength of LixSi is much higher than the generated stresses. Here, we suggest that stress relaxation is due to anisotropic (tensorial) compositional straining that occurs during insertion-extraction at any deviatoric stresses. Developed theory describes known experimental and atomistic simulation …
A Comparative Study Of Three Different Chemical Vapor Deposition Techniques Of Carbon Nanotube Growth On Diamond Films, Betty T. Quinton, Paul N. Barnes, Chakrapani V. Varanasi, Bang-Hung Tsao, Kevin J. Yost, Sharmila M. Mukhopadhyay
A Comparative Study Of Three Different Chemical Vapor Deposition Techniques Of Carbon Nanotube Growth On Diamond Films, Betty T. Quinton, Paul N. Barnes, Chakrapani V. Varanasi, Bang-Hung Tsao, Kevin J. Yost, Sharmila M. Mukhopadhyay
Mechanical and Materials Engineering Faculty Publications
This paper compares between the methods of growing carbon nanotubes (CNTs) on diamond substrates and evaluates the quality of the CNTs and the interfacial strength. One potential application for these materials is a heat sink/spreader for high-power electronic devices. The CNTs and diamond substrates have a significantly higher specific thermal conductivity than traditional heat sink/spreader materials making them good replacement candidates. Only limited research has been performed on these CNT/diamond structures and their suitability of different growth methods. This study investigates three potential chemical vapor deposition (CVD) techniques for growing CNTs on diamond: thermal CVD (T-CVD), microwave plasma-enhanced CVD (MPE-CVD), …
Nanomaterials Synthesis, Applications, And Toxicity 2012, Mallikarjuna Nadagouda, Dionysios Demetriou Dionysiou, Darren A. Lytle, Thomas F. Speth, Sharmila M. Mukhopadhyay
Nanomaterials Synthesis, Applications, And Toxicity 2012, Mallikarjuna Nadagouda, Dionysios Demetriou Dionysiou, Darren A. Lytle, Thomas F. Speth, Sharmila M. Mukhopadhyay
Mechanical and Materials Engineering Faculty Publications
Nanotechnology presents new opportunities to create better materials and products. Nanomaterials find wide applications in catalysis, energy production, medicine, environmental remediation, automotive industry, and other sectors of our society. Nanomaterial-containing products are already available globally and include automotive parts, defense application, drug delivery devices, coatings, computers, clothing, cosmetics, sports equipment, and medical devices. This special issue includes emerging advances in the field, with a special emphasis given to nanomaterial synthesis and applications.
Effects Of Crossflow Velocity And Transmembrane Pressure On Microfiltration Of Oil-In-Water Emulsions, Nikolai V. Priezjev, Tohid Darvishzadeh
Effects Of Crossflow Velocity And Transmembrane Pressure On Microfiltration Of Oil-In-Water Emulsions, Nikolai V. Priezjev, Tohid Darvishzadeh
Mechanical and Materials Engineering Faculty Publications
This study addresses the issue of oil removal from water using hydrophilic porous membranes. The effective separation of oil-in-water dispersions involves high flux of water through the membrane and, at the same time, high rejection rate of the oil phase. The effects of transmembrane pressure and crossflow velocity on rejection of oil droplets and thin oil films by pores of different cross-section are investigated numerically by solving the Navier-Stokes equation. We found that in the absence of crossflow, the critical transmembrane pressure, which is required for the oil droplet entry into a circular pore of a given surface hydrophilicity, agrees …
Analysis Of Solid Oxide Fuel Cell-Gas-Turbine Hybrid System Technology For Use In Aircraft, Jeremy Milliner, Rory Roberts
Analysis Of Solid Oxide Fuel Cell-Gas-Turbine Hybrid System Technology For Use In Aircraft, Jeremy Milliner, Rory Roberts
Explorations – The Journal of Undergraduate Research, Scholarship and Creativity at Wright State
Solid oxide fuel-cell-gas-turbine (SOFC/GT) hybrid systems are a technology that provides a more efficient source of energy for a variety of uses. One potential use is to provide more efficient energy to aircraft, which is the subject of this work. Potential applications to aircraft and results from a computer model of a SOFC/GT are presented here.
An Experimental Investigation On The Trailing Edge Cooling Of Turbine Blades, Zifeng Yang, Hui Hu
An Experimental Investigation On The Trailing Edge Cooling Of Turbine Blades, Zifeng Yang, Hui Hu
Mechanical and Materials Engineering Faculty Publications
An experimental study was conducted to quantify the flow characteristics of the wall jets pertinent to trailing edge cooling of turbine blades. A high-resolution stereoscopic particle image velocimetry (PIV) system was used to conduct detailed flow field measurements to quantitatively visualize the evolution of the unsteady vortices and turbulent flow structures in the cooling wall jet streams and to quantify the dynamic mixing process between the cooling jet stream and the mainstream flows. The detailed flow field measurements were correlated with the adiabatic cooling effectiveness maps measured by using pressure sensitive paint (PSP) technique to elucidate underlying physics in order …
Molecular Dynamics Simulations Of Oscillatory Couette Flows With Slip Boundary Conditions, Nikolai V. Priezjev
Molecular Dynamics Simulations Of Oscillatory Couette Flows With Slip Boundary Conditions, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The effect of interfacial slip on steady-state and time-periodic flows of monatomic liquids is investigated using non-equilibrium molecular dynamics simulations. The fluid phase is confined between atomically smooth rigid walls, and the fluid flows are induced by moving one of the walls. In steady shear flows, the slip length increases almost linearly with shear rate. We found that the velocity profiles in oscillatory flows are well described by the Stokes flow solution with the slip length that depends on the local shear rate. Interestingly, the rate dependence of the slip length obtained in steady shear flows is recovered when the …
Novel Platform Development Using Assembly Of Carbon Nanotube, Nanogold And Immobilized Rna Capture Element For Rapid, Selective Sensing Of Bacteria, Elizabeth I. Maurer, Kristen K. Comfort, Saber M. Hussain, John J. Schlager, Sharmila M. Mukhopadhyay
Novel Platform Development Using Assembly Of Carbon Nanotube, Nanogold And Immobilized Rna Capture Element For Rapid, Selective Sensing Of Bacteria, Elizabeth I. Maurer, Kristen K. Comfort, Saber M. Hussain, John J. Schlager, Sharmila M. Mukhopadhyay
Mechanical and Materials Engineering Faculty Publications
This study examines the creation of a nano-featured biosensor platform designed for the rapid and selective detection of the bacterium Escherichia coli. The foundation of this sensor is carbon nanotubes decorated with gold nanoparticles that are modified with a specific, surface adherent ribonucleiuc acid (RNA) sequence element. The multi-step sensor assembly was accomplished by growing carbon nanotubes on a graphite substrate, the direct synthesis of gold nanoparticles on the nanotube surface, and the attachment of thiolated RNA to the bound nanoparticles. The application of the compounded nano-materials for sensor development has the distinct advantage of retaining the electrical behavior …
Interfacial Friction Between Semiflexible Polymers And Crystalline Surfaces, Nikolai V. Priezjev
Interfacial Friction Between Semiflexible Polymers And Crystalline Surfaces, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The results obtained from molecular dynamics simulations of the friction at an interface between polymer melts and weakly attractive crystalline surfaces are reported. We consider a coarse-grained bead-spring model of linear chains with adjustable intrinsic stiffness. The structure and relaxation dynamics of polymer chains near interfaces are quantified by the radius of gyration and decay of the time autocorrelation function of the first normal mode. We found that the friction coefficient at small slip velocities exhibits a distinct maximum which appears due to shear-induced alignment of semiflexible chain segments in contact with solid walls. At large slip velocities, the friction …
Evaluating Superconducting Ybco Film Properties Using Xray Photoelectron Spectroscopy, Paul N. Barnes, Justin C. Tolliver, Timothy J. Haugan, Sharmila M. Mukhopadhyay, John T. Grant
Evaluating Superconducting Ybco Film Properties Using Xray Photoelectron Spectroscopy, Paul N. Barnes, Justin C. Tolliver, Timothy J. Haugan, Sharmila M. Mukhopadhyay, John T. Grant
Mechanical and Materials Engineering Faculty Publications
Initial results have been recently reported that suggest a potential correlation exists between the full-width-halfmaximum (FWHM) of the Y(3d) peak obtained by x-ray photoelectron spectroscopy (XPS) and the critical current density a YBa2Cu3O7-x film can carry. In particular, the Y(3d5/2) demonstrated a stronger correlation. Transport currents were determined by the 4-point contact method using the 1μV/cm criterion. An apparent correlation was also suggested between the Y(3d) FWHM and ac loss data points were acquired to further test the usefulness of the correlations. Samples were created by pulsed laser deposition of YBa2 …
Dechlorination Of Environmental Contaminants Using A Hybrid Nanocatalyst: Palladium Nanoparticles Supported On Hierarchical Carbon Nanostructures, Hema Vijwani, Abinash Agrawal, Sharmila M. Mukhopadhyay
Dechlorination Of Environmental Contaminants Using A Hybrid Nanocatalyst: Palladium Nanoparticles Supported On Hierarchical Carbon Nanostructures, Hema Vijwani, Abinash Agrawal, Sharmila M. Mukhopadhyay
Mechanical and Materials Engineering Faculty Publications
This paper demonstrates the effectiveness of a new type of hybrid nanocatalyst material that combines the high surface area of nanoparticles and nanotubes with the structural robustness and ease of handling larger supports. The hybrid material is made by fabricating palladium nanoparticles on two types of carbon supports: as-received microcellular foam (Foam) and foam with carbon nanotubes anchored on the pore walls (CNT/Foam). Catalytic reductive dechlorination of carbon tetrachloride with these materials has been investigated using gas chromatography. It is seen that while both palladium-functionalized carbon supports are highly effective in the degradation of carbon tetrachloride, the rate of degradation …
Molecular Diffusion And Slip Boundary Conditions At Smooth Surfaces With Periodic And Random Nanoscale Textures, Nikolai V. Priezjev
Molecular Diffusion And Slip Boundary Conditions At Smooth Surfaces With Periodic And Random Nanoscale Textures, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The influence of periodic and random surface textures on the flow structure and effective slip length in Newtonian fluids is investigated by molecular dynamics (MD) simulations. We consider a situation where the typical pattern size is smaller than the channel height and the local boundary conditions at wetting and nonwetting regions are characterized by finite slip lengths. In case of anisotropic patterns, transverse flow profiles are reported for flows over alternating stripes of different wettability when the shear flow direction is misaligned with respect to the stripe orientation. The angular dependence of the effective slip length obtained from MD simulations …
Fluid Structure And Boundary Slippage In Nanoscale Liquid Films, Nikolai V. Priezjev
Fluid Structure And Boundary Slippage In Nanoscale Liquid Films, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The book describes the concerted efforts of a large European research project and the achievements of additional leading research groups. The reported knowledge and expertise should support in the innovation and integration of often separated unitary processes. Sampling, cell lysis and DNA/RNA extraction, DNA hybridisation detection micro- and nanosensors, microfluidics, together also with computational modelling and risk assessment can be integrated in the framework of the current and evolving European regulations and needs. The development and uptake of molecular methods is revolutionizing the field of waterborne pathogens detection, commonly performed with time-consuming cultural methods. The molecular detection methods are enabling …
The Montana Mule: A Case Study In Interdisciplinary Capstone Design, Brock J. Lameres, Ahsan Mian, Hunter Lloyd, Robb Larson
The Montana Mule: A Case Study In Interdisciplinary Capstone Design, Brock J. Lameres, Ahsan Mian, Hunter Lloyd, Robb Larson
Mechanical and Materials Engineering Faculty Publications
The Montana MULE: A Case Study in Interdisciplinary Capstone Design In May of 2010, NASA held the 1st annual Lunabotics Mining Competition at theKennedy Space Center in Florida. In this competition, 22 teams from across the nationbuilt remote-controlled, robotic excavators to mine lunar regolith simulant. The winnerof the competition was the team who could successfully deposit the most regolith into acollector in 15 minutes. The goal of this competition was to encourage multidisciplinarycapstone design projects. Of the 22 teams that participated in the competition, the“Montana MULE” from Montana State University (MSU) was the only robot tosuccessfully mine the qualifying weight …
The Relationship Between Induced Fluid Structure And Boundary Slip In Nanoscale Polymer Films, Nikolai V. Priezjev
The Relationship Between Induced Fluid Structure And Boundary Slip In Nanoscale Polymer Films, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The molecular mechanism of slip at the interface between polymer melts and weakly attractive smooth surfaces is investigated using molecular dynamics simulations. In agreement with our previous studies on slip flow of shear-thinning fluids, it is shown that the slip length passes through a local minimum at low shear rates and then increases rapidly at higher shear rates. We found that at sufficiently high shear rates, the slip flow over atomically flat crystalline surfaces is anisotropic. It is demonstrated numerically that the friction coefficient at the liquid-solid interface (the ratio of viscosity and slip length) undergoes a transition from a …
Slip Boundary Conditions For The Moving Contact Line In Molecular Dynamics And Continuum Simulations, Nikolai V. Priezjev, Anoosheh Niavarani
Slip Boundary Conditions For The Moving Contact Line In Molecular Dynamics And Continuum Simulations, Nikolai V. Priezjev, Anoosheh Niavarani
Mechanical and Materials Engineering Faculty Publications
The problem of the moving contact line between two immiscible fluids on a smooth surface is revisited using molecular dynamics (MD) and continuum simulations. In MD simulations a finite slip is allowed by choosing incommensurate wall-fluid densities and weak wall-fluid interaction energies. The shear stresses and velocity fields are extracted carefully in the bulk fluid region as well as near the moving contact line. In agreement with previous studies, we found slowly decaying partial slip region away from the contact line. In steady-state shear flows we extract the friction coefficient along the liquid-solid interface, the local slip length, and the …
Modeling The Combined Effect Of Surface Roughness And Shear Rate On Slip Flow Of Simple Fluids, Nikolai V. Priezjev, Anoosheh Niavarani
Modeling The Combined Effect Of Surface Roughness And Shear Rate On Slip Flow Of Simple Fluids, Nikolai V. Priezjev, Anoosheh Niavarani
Mechanical and Materials Engineering Faculty Publications
Molecular dynamics (MD) and continuum simulations are carried out to investigate the influence of shear rate and surface roughness on slip flow of a Newtonian fluid. For weak wall-fluid interaction energy, the nonlinear shear-rate dependence of the intrinsic slip length in the flow over an atomically flat surface is computed by MD simulations. We describe laminar flow away from a curved boundary by means of the effective slip length defined with respect to the mean height of the surface roughness. Both the magnitude of the effective slip length and the slope of its rate-dependence are significantly reduced in the presence …
Shear Rate Threshold For The Boundary Slip In Dense Polymer Films, Nikolai V. Priezjev
Shear Rate Threshold For The Boundary Slip In Dense Polymer Films, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The shear rate dependence of the slip length in thin polymer films confined between atomically flat surfaces is investigated by molecular dynamics simulations. The polymer melt is described by the bead-spring model of linear flexible chains. We found that at low shear rates the velocity profiles acquire a pronounced curvature near the wall and the absolute value of the negative slip length is approximately equal to thickness of the viscous interfacial layer. At higher shear rates, the velocity profiles become linear and the slip length increases rapidly as a function of shear rate. The gradual transition from no-slip to steady-state …
The Effective Slip Length And Vortex Formation In Laminar Flow Over A Rough Surface, Anoosheh Niavarani, Nikolai V. Priezjev
The Effective Slip Length And Vortex Formation In Laminar Flow Over A Rough Surface, Anoosheh Niavarani, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The flow of viscous incompressible fluid over a periodically corrugated surface is investigated numerically by solving the Navier–Stokes equation with the local slip and no-slip boundary conditions. We consider the effective slip length which is defined with respect to the level of the mean height of the surface roughness. With increasing corrugation amplitude the effective no-slip boundary plane is shifted toward the bulk of the fluid, which implies a negative effective slip length. The analysis of the wall shear stress indicates that a flow circulation is developed in the grooves of the rough surface provided that the local boundary condition …
Rheological Study Of Polymer Flow Past Rough Surfaces With Slip Boundary Conditions, Anoosheh Niavarani, Nikolai V. Priezjev
Rheological Study Of Polymer Flow Past Rough Surfaces With Slip Boundary Conditions, Anoosheh Niavarani, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
The slip phenomena in thin polymer films confined by either flat or periodically corrugated surfaces are investigated by molecular dynamics and continuum simulations. For atomically flat surfaces and weak wall-fluid interactions, the shear rate dependence of the slip length has a distinct local minimum which is followed by a rapid increase at higher shear rates. For corrugated surfaces with wavelength larger than the radius of gyration of polymer chains, the effective slip length decays monotonically with increasing corrugation amplitude. At small amplitudes, this decay is reproduced accurately by the numerical solution of the Stokes equation with constant and rate-dependent local …
Slip Boundary Conditions For Shear Flow Of Polymer Melts Past Atomically Flat Surfaces, Anoosheh Niavarani, Nikolai V. Priezjev
Slip Boundary Conditions For Shear Flow Of Polymer Melts Past Atomically Flat Surfaces, Anoosheh Niavarani, Nikolai V. Priezjev
Mechanical and Materials Engineering Faculty Publications
Molecular dynamics simulations are carried out to investigate the dynamic behavior of the slip length in thin polymer films confined between atomically smooth thermal surfaces. For weak wall-fluid interactions, the shear rate dependence of the slip length acquires a distinct local minimum followed by a rapid growth at higher shear rates. With increasing fluid density, the position of the local minimum is shifted to lower shear rates. We found that the ratio of the shear viscosity to the slip length, which defines the friction coefficient at the liquid/solid interface, undergoes a transition from a nearly constant value to the power …