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 Selected recent publications (15)
 Electrospinning (5)
 Presentations (4)
 Electrophoresis (3)
 Mathematical Modeling (3)

 Selfassembly (3)
 Theory and models of film growth (3)
 Morphology of films (3)
 Dewetting (2)
 Pulsed laser irradiation (2)
 Thermocapillary convection (2)
 Microfluidics (2)
 Selforganization (2)
 Particle size (2)
 Liquid bilayer films (2)
 Nanofluidics (2)
 BioMEMS (2)
 Interfacial stabil ity (2)
 Electrodes (2)
 Nanopatterning (2)
 Biological fluid dynamics (1)
 Biological techniques (1)
 Biomolecule characterization (1)
 Applied sciences (1)
 Aggregation (1)
 Auxiliary Electric Fields (1)
 Bacterial spores (1)
 Accommodation coefficient (1)
 Bioelectric phenomena (1)
 Bacteria (1)
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Articles 1  30 of 52
FullText Articles in Nanoscience and Nanotechnology
Modeling Multiphase Flow And Substrate Deformation In Nanoimprint Manufacturing Systems, Andrew Cochrane
Modeling Multiphase Flow And Substrate Deformation In Nanoimprint Manufacturing Systems, Andrew Cochrane
Nanoscience and Microsystems ETDs
Nanopatterns found in nature demonstrate that macroscopic properties of a surface are tied to its nanoscale structure. Tailoring the nanostructure allows those macroscopic surface properties to be engineered. However, a capabilitygap in manufacturing technology inhibits massproduction of nanotechnologies based on simple, nanometerscale surface patterns. This gap represents an opportunity for research and development of nanoimprint lithography (NIL) processes. NIL is a process for replicating patterns by imprinting a fluid layer with a solid, nanopatterned template, after which ultraviolet cure solidifies the fluid resulting in a nanopatterned surface. Although NIL has been demonstrated to replicate pattern features as small as 4 ...
Swelling As A Stabilizing Mechanism During Ion Bombardment Of Thin Films: An Analytical And Numerical Study, Jennifer M. Swenson
Swelling As A Stabilizing Mechanism During Ion Bombardment Of Thin Films: An Analytical And Numerical Study, Jennifer M. Swenson
Mathematics Theses and Dissertations
Irradiation of semiconductor surfaces often leads to the spontaneous formation of rippled structures at certain irradiation angles. However, at high enough energies, these structures are observed to vanish for all angles, despite the absence of any identified, universallystabilizing physical mechanisms in operation. Here, we examine the effect on pattern formation of radiationinduced swelling, which has been excluded from prior treatments of stress in irradiated films. After developing a suitable continuum model, we perform a linear stability analysis to determine its effect on stability. Under appropriate simplifying assumptions, we find swelling indeed to be stabilizing at wavenumbers typical of experimental observations ...
Electroosmotic Flow Of Viscoelastic Fluid In A Nanoslit, Lanju Mei, Hongna Zhang, Hongxia Meng, Shizhi Qian
Electroosmotic Flow Of Viscoelastic Fluid In A Nanoslit, Lanju Mei, Hongna Zhang, Hongxia Meng, Shizhi Qian
Mechanical & Aerospace Engineering Faculty Publications
The electroosmotic flow (EOF) of viscoelastic fluid in a long nanoslit is numerically studied to investigate the rheological property effect of Linear PhanThienTanner (LPTT) fluid on the fully developed EOF. The nonlinear PoissonNernstPlanck equations governing the electric potential and the ionic concentration distribution within the channel are adopted to take into account the effect of the electrical double layer (EDL), including the EDL overlap. When the EDL is not overlapped, the velocity profiles for both Newtonian and viscoelastic fluids are pluglike and increase sharply near the charged wall. The velocity profile resembles that of pressuredriven flow when the EDL is ...
An Assessment Of The Validity Of The Kinetic Model For LiquidVapor Phase Change By Examining Cryogenic Propellants, Kishan Bellur
An Assessment Of The Validity Of The Kinetic Model For LiquidVapor Phase Change By Examining Cryogenic Propellants, Kishan Bellur
Dissertations, Master's Theses and Master's Reports
Evaporation is ubiquitous in nature and occurs even in a microgravity space envi ronment. Long term space missions require storage of cryogenic propellents and an accurate prediction of phase change rates. Kinetic theory has been used to model and predict evaporation rates for over a century but the reported values of accommodation coefficients are highly inconsistent and no accurate data is available for cryogens. The proposed study involves a combined experimental and computational approach to ex tract the accommodation coefficients. Neutron imaging is used as the visualization technique due to the difference in attenuation between the cryogen and the metallic ...
Microfluidic Electrical Sorting Of Particles Based On Shape In A Spiral Microchannel, John Dubose, Xinyu Lu, Saurin Patel, Shizhi Qian, Sang Woo Joo
Microfluidic Electrical Sorting Of Particles Based On Shape In A Spiral Microchannel, John Dubose, Xinyu Lu, Saurin Patel, Shizhi Qian, Sang Woo Joo
Mechanical & Aerospace Engineering Faculty Publications
Shape is an intrinsic marker of cell cycle, an important factor for identifying a bioparticle, and also a useful indicator of cell state for disease diagnostics. Therefore, shape can be a specific marker in labelfree particle and cell separation for various chemical and biological applications. We demonstrate in this work a continuousflow electrical sorting of spherical and peanutshaped particles of similar volumes in an asymmetric doublespiral microchannel. It exploits curvatureinduced dielectrophoresis to focus particles to a tight stream in the first spiral without any sheath flow and subsequently displace them to shapedependent flow paths in the second spiral without any ...
An Unexpected Particle Oscillation For Electrophoresis In Viscoelastic Fluids Through A Microchannel Constriction, Xinyu Lu, Saurin Patel, Meng Zhang, Sang Woo Joo, Shizhi Qian, Amod Ogale, Xiangchun Xuan
An Unexpected Particle Oscillation For Electrophoresis In Viscoelastic Fluids Through A Microchannel Constriction, Xinyu Lu, Saurin Patel, Meng Zhang, Sang Woo Joo, Shizhi Qian, Amod Ogale, Xiangchun Xuan
Mechanical & Aerospace Engineering Faculty Publications
Electrophoresis plays an important role in many applications, which, however, has so far been extensively studied in Newtonian fluids only. This work presents the first experimental investigation of particle electrophoresis in viscoelastic polyethylene oxide (PEO) solutions through a microchannel constriction under pure DC electric fields. An oscillatory particle motion is observed in the constriction region, which is distinctly different from the particle behavior in a polymerfree Newtonian fluid. This streamwise particle oscillation continues until a sufficient number of particles form a chain to pass through the constriction completely. It is speculated that such an unexpected particle oscillating phenomenon is a ...
NearInfrared SurfaceEnhanced Fluorescence Using Silver Nanoparticles In Solution, Michael D. Furtaw
NearInfrared SurfaceEnhanced Fluorescence Using Silver Nanoparticles In Solution, Michael D. Furtaw
Mechanical (and Materials) Engineering  Dissertations, Theses, and Student Research
Fluorescence spectroscopy is a widely used detection technology in many research and clinical assays. Further improvement to assay sensitivity may enable earlier diagnosis of disease, novel biomarker discovery, and ultimately, improved outcomes of clinical care along with reduction in costs. Nearinfrared, surfaceenhanced fluorescence (NIRSEF) is a promising approach to improve assay sensitivity via simultaneous increase in signal with a reduction in background. This dissertation describes research conducted with the overall goal to determine the extent to which fluorescence in solution may be enhanced by altering specific variables involved in the formation of plasmonactive nanostructures of dyelabeled protein and silver nanoparticles ...
Design And Fabrication Of Nanofluidic Systems With Integrated Sensing Electrodes For Rapid Biomolecule Characterization, Taylor Bradley Busch
Design And Fabrication Of Nanofluidic Systems With Integrated Sensing Electrodes For Rapid Biomolecule Characterization, Taylor Bradley Busch
Theses and Dissertations
A transparent nanofluidic system with embedded sensing electrodes was designed and fabricated by integrating Atomic Force Microscopy (AFM) nanolithography, Focused Ion Beam (FIB) milling and metal deposition, and standard microfabrication processing. The fabrication process started with the evaporation of chrome/gold (Cr/Au) onto a Pyrex 7740 wafer followed by photolithography and wet etching of the microchannels. The wafer was patterned a second time to form Au microelectrodes with 1545 micrometer separation gaps in the nanochannel region. Sensing electrodes (up to one micron wide) were then deposited using FIB to bridge the gaps. The nanochannels were realized through both AFM ...
Manipulation Of Electrospun Fibres In Flight: The Principle Of Superposition Of Electric Fields As A Control Method, Nurfaizey A. Hamid, Jonathan J. Stanger, Nick Tucker, Andrew Wallace, Mark P. Staiger
Manipulation Of Electrospun Fibres In Flight: The Principle Of Superposition Of Electric Fields As A Control Method, Nurfaizey A. Hamid, Jonathan J. Stanger, Nick Tucker, Andrew Wallace, Mark P. Staiger
Jonathan J Stanger
This study investigates the magnitude of movement of the area of deposition of electrospun fibres in response to an applied auxiliary electric field. The auxiliary field is generated by two pairs of rod electrodes positioned adjacent and parallel to the line of flight of the spun fibre. The changes in shape of the deposition area and the degree of movement of the deposition area are quantified by optical scanning and image analysis. A linear response was observed between the magnitude of movement of the deposition area and voltage difference between the auxiliary and deposition electrodes. A squeezing effect which changed ...
Controlling Nanoparticles Formation In Molten Metallic Bilayers By PulsedLaser Interference Heating, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman
Controlling Nanoparticles Formation In Molten Metallic Bilayers By PulsedLaser Interference Heating, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman
Mathematics Faculty Publications
The impacts of the twobeam interference heating on the number of coreshell and embedded nanoparticles and on nanostructure coarsening are studied numerically based on the nonlinear dynamical model for dewetting of the pulsedlaser irradiated, thin (< 20 nm) metallic bilayers. The model incorporates thermocapillary forces and disjoining pressures, and assumes dewetting from the optically transparent substrate atop of the reflective support layer, which results in the complicated dependence of light reflectivity and absorption on the thicknesses of the layers. Stabilizing thermocapillary effect is due to the local thicknessdependent, steady state temperature profile in the liquid, which is derived based on the mean substrate temperature estimated from the elaborate thermal model of transient heating and melting/freezing. Linear stability analysis of the model equations set for Ag/Co bilayer predicts the dewetting length scales in the qualitative agreement with experiment.
Microfluidic Separation Of Live And Dead Yeast Cells Using ReservoirBased Dielectrophoresis, Saurin Patel, Daniel Showers, Pallavi Vedantam, TzuenRong Tzeng, Shizhi Qian, Xiangchun Xuan
Microfluidic Separation Of Live And Dead Yeast Cells Using ReservoirBased Dielectrophoresis, Saurin Patel, Daniel Showers, Pallavi Vedantam, TzuenRong Tzeng, Shizhi Qian, Xiangchun Xuan
Mechanical & Aerospace Engineering Faculty Publications
Separating live and dead cells is critical to the diagnosis of early stage diseases and to the efficacy test of drug screening, etc. This work demonstrates a novel microfluidic approach to dielectrophoretic separation of yeast cells by viability. It exploits the cell dielectrophoresis that is induced by the inherent electric field gradient at the reservoirmicrochannel junction to selectively trap dead yeast cells and continuously separate them from live ones right inside the reservoir. This approach is therefore termed reservoirbased dielectrophoresis (rDEP). It has unique advantages as compared to existing dielectrophoretic approaches such as the occupation of zero channel space and ...
Controlling Nanoparticles Formation In Molten Metallic Bilayers By PulsedLaser Interference Heating, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman
Controlling Nanoparticles Formation In Molten Metallic Bilayers By PulsedLaser Interference Heating, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman
Mikhail Khenner
The impacts of the twobeam interference heating on the number of coreshell and embedded nanoparticles and on nanostructure coarsening are studied numerically based on the nonlinear dynamical model for dewetting of the pulsedlaser irradiated, thin (< 20 nm) metallic bilayers. The model incorporates thermocapillary forces and disjoining pressures, and assumes dewetting from the optically transparent substrate atop of the reflective support layer, which results in the complicated dependence of light reflectivity and absorption on the thicknesses of the layers. Stabilizing thermocapillary effect is due to the local thicknessdependent, steady state temperature profile in the liquid, which is derived based on the mean substrate temperature estimated from the elaborate thermal model of transient heating and melting/freezing. Linear stability analysis of the model equations set for Ag/Co bilayer predicts the dewetting length scales in the qualitative agreement with experiment.
The Nanoaquarium: A Nanofluidic Platform For In Situ Transmission Electron Microscopy In Liquid Media, Joseph M. Grogan
The Nanoaquarium: A Nanofluidic Platform For In Situ Transmission Electron Microscopy In Liquid Media, Joseph M. Grogan
Publicly Accessible Penn Dissertations
There are many scientifically interesting and technologically relevant nanoscale phenomena that take place in liquid media. Examples include aggregation and assembly of nanoparticles; colloidal crystal formation; liquid phase growth of structures such as nanowires; electrochemical deposition and etching for fabrication processes and battery applications; interfacial phenomena; boiling and cavitation; and biological interactions. Understanding of these fields would benefit greatly from realtime, in situ transmission electron microscope (TEM) imaging with nanoscale resolution. Most liquids cannot be imaged by traditional TEM due to evaporation in the high vacuum environment and the requirement that samples be very thin. Liquidcell in situ TEM has ...
Formation Of Organized Nanostructures From Unstable Bilayers Of Thin Metallic Liquids, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman
Formation Of Organized Nanostructures From Unstable Bilayers Of Thin Metallic Liquids, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman
Mathematics Faculty Publications
Dewetting of pulsedlaser irradiated, thin (< 20 nm), optically reflective metallic bilayers on an optically transparent substrate with a reflective support layer is studied within the lubrication equations model. A steadystate bilayer film thickness (h) dependent temperature profile is derived based on the mean substrate temperature estimated from the elaborate thermal model of transient heating and melting/freezing. Large thermocapillary forces are observed along the plane of the liquidliquid and liquidgas interfaces due to this hdependent temperature, which, in turn, is strongly influenced by the hdependent laser light reflection and absorption. Consequently the dewetting is a result of the competition between thermocapillary and intermolecular forces. A linear analysis of the dewetting length scales established that the nonisothermal calculations better predict the experimental results as compared to the isothermal case within the bounding Hamaker coefficients. Subsequently, a computational nonlinear dynamics study of the dewetting pathway was performed for Ag/Co and Co/Ag bilayer systems to predict the morphology evolution. We found that the systems evolve towards formation of different morphologies, including coreshell, embedded, or stacked nanostructure morphologies.
Formation Of Organized Nanostructures From Unstable Bilayers Of Thin Metallic Liquids, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman
Formation Of Organized Nanostructures From Unstable Bilayers Of Thin Metallic Liquids, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman
Mikhail Khenner
Dewetting of pulsedlaser irradiated, thin (< 20 nm), optically reflective metallic bilayers on an optically transparent substrate with a reflective support layer is studied within the lubrication equations model. A steadystate bilayer film thickness (h) dependent temperature profile is derived based on the mean substrate temperature estimated from the elaborate thermal model of transient heating and melting/freezing. Large thermocapillary forces are observed along the plane of the liquidliquid and liquidgas interfaces due to this hdependent temperature, which, in turn, is strongly influenced by the hdependent laser light reflection and absorption. Consequently the dewetting is a result of the competition between thermocapillary and intermolecular forces. A linear analysis of the dewetting length scales established that the nonisothermal calculations better predict the experimental results as compared to the isothermal case within the bounding Hamaker coefficients. Subsequently, a computational nonlinear dynamics study of the dewetting pathway was performed for Ag/Co and Co/Ag bilayer systems to predict the morphology evolution. We found that the systems evolve towards formation of different morphologies, including coreshell, embedded, or stacked nanostructure morphologies.
Stability Of A Strongly Anisotropic Thin Epitaxial Film In A Wetting Interaction With Elastic Substrate, Mikhail Khenner, Wondimu Tekalign, Margo Levine
Stability Of A Strongly Anisotropic Thin Epitaxial Film In A Wetting Interaction With Elastic Substrate, Mikhail Khenner, Wondimu Tekalign, Margo Levine
Mathematics Faculty Publications
The linear dispersion relation for longwave surface perturbations, as derived by Levine et al. Phys. Rev. B 75, 205312 (2007) is extended to include a smooth surface energy anisotropy function with a variable anisotropy strength (from weak to strong, such that sharp corners and slightly curved facets occur on the corresponding Wulff shape). Through detailed parametric studies it is shown that a combination of a wetting interaction and strong anisotropy, and even a wetting interaction alone results in complicated linear stability characteristics of strained and unstrained films.
Modeling Diverse Physics Of Nanoparticle SelfAssembly In Pulsed LaserIrradiated Metallic Films, Mikhail Khenner
Modeling Diverse Physics Of Nanoparticle SelfAssembly In Pulsed LaserIrradiated Metallic Films, Mikhail Khenner
Mathematics Faculty Publications
Presents physics behind dewetting of thin liquid films and mathematical/computational modeling tools (Educational/Research presentation for senior physics majors).
Stability Of A Strongly Anisotropic Thin Epitaxial Film In A Wetting Interaction With Elastic Substrate, Mikhail Khenner, Wondimu T. Tekalign, Margo S. Levine
Stability Of A Strongly Anisotropic Thin Epitaxial Film In A Wetting Interaction With Elastic Substrate, Mikhail Khenner, Wondimu T. Tekalign, Margo S. Levine
Mathematics Faculty Publications
The linear dispersion relation for longwave surface perturbations, as derived by Levine et al. Phys. Rev. B 75, 205312 (2007) is extended to include a smooth surface energy anisotropy function with a variable anisotropy strength (from weak to strong, such that sharp corners and slightly curved facets occur on the corresponding Wulff shape). Through detailed parametric studies it is shown that a combination of a wetting interaction and strong anisotropy, and even a wetting interaction alone results in complicated linear stability characteristics of strained and unstrained films.
A Cell Electrofusion Microfluidic Device Integrated With 3d ThinFilm Microelectrode Arrays, Ning Hu, Jun Yang, Shizhi Qian, Sang W. Joo, Xiaolin Zheng
A Cell Electrofusion Microfluidic Device Integrated With 3d ThinFilm Microelectrode Arrays, Ning Hu, Jun Yang, Shizhi Qian, Sang W. Joo, Xiaolin Zheng
Mechanical & Aerospace Engineering Faculty Publications
A microfluidic device integrated with 3D thin film microelectrode arrays wrapped around serpentineshaped microchannel walls has been designed, fabricated and tested for cell electrofusion. Each microelectrode array has 1015 discrete microelectrodes patterned on each side wall, and the adjacent microelectrodes are separated by coplanar dielectric channel wall. The device was tested to electrofuse K562 cells under a relatively low voltage. Under an AC electric field applied between the pair of the microelectrode arrays, cells are paired at the edge of each discrete microelectrode due to the induced positive dielectrophoresis. Subsequently, electric pulse signals are sequentially applied between the microelectrode arrays ...
Stability Of A Strongly Anisotropic Thin Epitaxial Film In A Wetting Interaction With Elastic Substrate, Mikhail Khenner, Wondimu T. Tekalign, Margo S. Levine
Stability Of A Strongly Anisotropic Thin Epitaxial Film In A Wetting Interaction With Elastic Substrate, Mikhail Khenner, Wondimu T. Tekalign, Margo S. Levine
Mikhail Khenner
The linear dispersion relation for longwave surface perturbations, as derived by Levine et al. Phys. Rev. B 75, 205312 (2007) is extended to include a smooth surface energy anisotropy function with a variable anisotropy strength (from weak to strong, such that sharp corners and slightly curved facets occur on the corresponding Wulff shape). Through detailed parametric studies it is shown that a combination of a wetting interaction and strong anisotropy, and even a wetting interaction alone results in complicated linear stability characteristics of strained and unstrained films.
Modeling Diverse Physics Of Nanoparticle SelfAssembly In Pulsed LaserIrradiated Metallic Films, Mikhail Khenner
Modeling Diverse Physics Of Nanoparticle SelfAssembly In Pulsed LaserIrradiated Metallic Films, Mikhail Khenner
Mikhail Khenner
Presents physics behind dewetting of thin liquid films and mathematical/computational modeling tools (Educational/Research presentation for senior physics majors).
Negative Dielectrophoretic Capture Of Bacterial Spores In Food Matrices, Mehti Koklu, Seungkyung Park, Suresh D. Pillai, Ali Beskok
Negative Dielectrophoretic Capture Of Bacterial Spores In Food Matrices, Mehti Koklu, Seungkyung Park, Suresh D. Pillai, Ali Beskok
Mechanical & Aerospace Engineering Faculty Publications
A microfluidic device with planar square electrodes is developed for capturing particles from high conductivity media using negative dielectrophoresis (nDEP). Specifically, Bacillus subtilis and Clostridium sporogenes spores, and polystyrene particles are tested in NaCl solution (0.05 and 0.225 S/m), apple juice (0.225 S/m), and milk (0.525 S/m). Depending on the conductivity of the medium, the Joule heating produces electrothermal flow (ETF), which continuously circulates and transports the particles to the DEP capture sites. Combination of the ETF and nDEP results in different particle capture efficiencies as a function of the conductivity. Utilizing 20 ...
Morphological Evolution Of SingleCrystal Ultrathin Solid Films, Mikhail Khenner
Morphological Evolution Of SingleCrystal Ultrathin Solid Films, Mikhail Khenner
Mathematics Faculty Publications
An introduction to mathematical modeling of ultrathin solid films and the role of such modeling in nanotechnologies: Educational/Research presentation for senior physics majors
Morphological Evolution Of SingleCrystal Ultrathin Solid Films, Mikhail Khenner
Morphological Evolution Of SingleCrystal Ultrathin Solid Films, Mikhail Khenner
Mathematics Faculty Publications
An introduction to mathematical modeling of ultrathin solid films and the role of such modeling in nanotechnologies: Educational presentation for senior physics majors
Morphological Evolution Of SingleCrystal Ultrathin Solid Films, Mikhail Khenner
Morphological Evolution Of SingleCrystal Ultrathin Solid Films, Mikhail Khenner
Mikhail Khenner
An introduction to mathematical modeling of ultrathin solid films and the role of such modeling in nanotechnologies: Educational/Research presentation for senior physics majors
Oscillatory And Monotonic Modes Of LongWave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev
Oscillatory And Monotonic Modes Of LongWave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev
Mathematics Faculty Publications
We study longwave Marangoni convection in a layer heated from below. Using the scaling k=O Bi, where k is the wave number and Bi is the Biot number, we derive a set of amplitude equations. Analysis of this set shows presence of monotonic and oscillatory modes of instability. Oscillatory mode has not been previously found for such direction of heating. Studies of weakly nonlinear dynamics demonstrate that stable steady and oscillatory patterns can be found near the stability threshold.
Oscillatory And Monotonic Modes Of LongWave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev
Oscillatory And Monotonic Modes Of LongWave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev
Mathematics Faculty Publications
We study longwave Marangoni convection in a layer heated from below. Using the scaling k=O Bi, where k is the wave number and Bi is the Biot number, we derive a set of amplitude equations. Analysis of this set shows presence of monotonic and oscillatory modes of instability. Oscillatory mode has not been previously found for such direction of heating. Studies of weakly nonlinear dynamics demonstrate that stable steady and oscillatory patterns can be found near the stability threshold.
Dielectrophoretic Choking Phenomenon In A ConvergingDiverging Microchannel, Ye Ai, Shizhi Qian, Sheng Liu, Sang W. Joo
Dielectrophoretic Choking Phenomenon In A ConvergingDiverging Microchannel, Ye Ai, Shizhi Qian, Sheng Liu, Sang W. Joo
Mechanical & Aerospace Engineering Faculty Publications
Experiments show that particles smaller than the throat size of convergingdiverging microchannels can sometimes be trapped near the throat. This critical phenomenon is associated with the negative dc dielectrophoresis arising from nonuniform electric fields in the microchannels. A finiteelement model, accounting for the particlefluidelectric field interactions, is employed to investigate the conditions for this dielectrophoretic (DEP) choking in a convergingdiverging microchannel for the first time. It is shown quantitatively that the DEP choking occurs for high nonuniformity of electric fields, high ratio of particle size to throat size, and high ratio of particle's zeta potential to that of microchannel ...
A TangentPlane, MarkerParticle Method For The Computation Of ThreeDimensional Solid Surfaces Evolving By Surface Diffusion On A Substrate, Ping Du, Mikhail Khenner, Harris Wong
A TangentPlane, MarkerParticle Method For The Computation Of ThreeDimensional Solid Surfaces Evolving By Surface Diffusion On A Substrate, Ping Du, Mikhail Khenner, Harris Wong
Mikhail Khenner
We introduce a markerparticle method for the computation of threedimensional solid surface morphologies evolving by surface diffusion. The method does not use gridding of surfaces or numerical differentiation, and applies to surfaces with finite slopes and overhangs. We demonstrate the method by computing the evolution of perturbed cylindrical wires on a substrate. We show that computed growth rates at early times agree with those predicted by the linear stability analysis. Furthermore, when the marker particles are redistributed periodically to maintain even spacing, the method can follow breakup of the wire.
Oscillatory And Monotonic Modes Of LongWave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev
Oscillatory And Monotonic Modes Of LongWave Marangoni Convection In A Thin Film, Sergey Shklyaev, Mikhail Khenner, Alexei Alabuzhev
Mikhail Khenner
We study longwave Marangoni convection in a layer heated from below. Using the scaling k=O#1;#3;Bi#2;, where k is the wave number and Bi is the Biot number, we derive a set of amplitude equations. Analysis of this set shows presence of monotonic and oscillatory modes of instability. Oscillatory mode has not been previously found for such direction of heating. Studies of weakly nonlinear dynamics demonstrate that stable steady and oscillatory patterns can be found near the stability threshold.