On The Influence Of Damping In Hyperbolic Equations With Parabolic Degeneracy, 2011 University of New Orleans
On The Influence Of Damping In Hyperbolic Equations With Parabolic Degeneracy, Ralph Saxton, Katarzyna Saxton
Ralph Saxton
This paper examines the effect of damping on a nonstrictly hyperbolic 2x2 system. It is shown that the growth of singularities is not restricted as in the strictly hyperbolic case where dissipation can be strong enough to preserve the smoothness of solutions globally in time. Here, irrespective of the stabilizing properties of damping, solutions are found to break down in finite time on a line where two eigenvalues coincide in state space.
Nonlinear Waves And Solitons On Contours And Closed Surfaces, 2011 Embry-Riddle Aeronautical University
Nonlinear Waves And Solitons On Contours And Closed Surfaces, Andrei Ludu
Andrei Ludu
No abstract provided.
Hydrogen Production From Biogas By Oxy-Reforming: Reaction System Analysis, 2011 Wroclaw University of Technology
Hydrogen Production From Biogas By Oxy-Reforming: Reaction System Analysis, Aleksandra Terlecka, Wojciech M. Budzianowski
Wojciech Budzianowski
Oxy-reforming is emerging as an interesting alternative to conventional methods of hydrogen generation. The current article characterises this process through analysis of individual reactions: SMR (steam methane reforming), WGS (water gas shift) and CPO (catalytic partial oxidation). Analyses relate to optimisation of thermal conditions thus enabling cost-effectivenes of the process.
Formation Of Organized Nanostructures From Unstable Bilayers Of Thin Metallic Liquids, 2011 Western Kentucky University
Formation Of Organized Nanostructures From Unstable Bilayers Of Thin Metallic Liquids, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman
Mathematics Faculty Publications
Dewetting of pulsed-laser 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 steady-state 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 liquid-liquid and liquid-gas interfaces due to this h-dependent temperature, which, in turn, is strongly influenced by the h-dependent 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 non-isothermal calculations better predict the experimental results as compared to the isothermal case within the bounding Hamaker coefficients. Subsequently, a computational non-linear 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 core-shell, embedded, or stacked nanostructure morphologies.
Formation Of Organized Nanostructures From Unstable Bilayers Of Thin Metallic Liquids, 2011 Western Kentucky University
Formation Of Organized Nanostructures From Unstable Bilayers Of Thin Metallic Liquids, Mikhail Khenner, Sagar Yadavali, Ramki Kalyanaraman
Mikhail Khenner
Dewetting of pulsed-laser 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 steady-state 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 liquid-liquid and liquid-gas interfaces due to this h-dependent temperature, which, in turn, is strongly influenced by the h-dependent 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 non-isothermal calculations better predict the experimental results as compared to the isothermal case within the bounding Hamaker coefficients. Subsequently, a computational non-linear 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 core-shell, embedded, or stacked nanostructure morphologies.
Stability Of Stratified Couple-Stress Dusty Fluid In The Presence Of Magnetic Field Through Porous Medium, 2011 University of Petroleum & Energy Studies (UPES)
Stability Of Stratified Couple-Stress Dusty Fluid In The Presence Of Magnetic Field Through Porous Medium, Vivek Kumar
Applications and Applied Mathematics: An International Journal (AAM)
The combined effect of magnetic field and dust particles on the stability of a stratified couplestress fluid through a porous medium is considered. For stable stratification, the system is found to be stable for disturbances of all wave numbers. The magnetic field succeeds in stabilizing the potentially unstable stratifications for a certain wave-number range which were unstable in the absence of the magnetic field. Discussions of oscillatory and non-oscillatory modes are also made.
Lectio Praecursoria, 2011 Lappeenranta University of Technology
Lectio Praecursoria, Kari Myöhänen
Kari Myöhänen
Lectio praecursoria: Modelling of combustion and sorbent reactions in three-dimensional flow environment of a circulating fluidized bed furnace
Peristaltic Induced Flow Of A Two-Layered Suspension In Non-Uniform Channel, 2011 Kamla Nehru Institute of Technology
Peristaltic Induced Flow Of A Two-Layered Suspension In Non-Uniform Channel, Amit Medhavi, Dharmendra Singh, Ajay S. Yadav, Ramesh S. Gautam
Applications and Applied Mathematics: An International Journal (AAM)
Peristaltic transport of a two-layered particulate suspension in a non-uniform channel has been investigated. The coupled differential equations for both the fluid and the particle phases in the central as well as in the peripheral layers have been solved and the expression for the flow rate, the pressure rise and the friction force has been derived. The results obtained are discussed both qualitatively and quantitatively in brief. The significance of the particle concentration as well as the peripheral layer has been well explained.
The Power Series Solution Of Fingering Phenomenon Arising In Fluid Flow Through Homogeneous Porous Media, 2011 S.V. National Institute of Technology
The Power Series Solution Of Fingering Phenomenon Arising In Fluid Flow Through Homogeneous Porous Media, Kinjal Patel, M. N. Mehta, Twinkle R. Patel
Applications and Applied Mathematics: An International Journal (AAM)
The present paper deals with the approximate solution of the fingering phenomenon occurring when water is pushed into oil in homogeneous porous media with capillary mean pressure. The phenomenon is formulated mathematically as a water-oil double phase flow problem. The solution of the nonlinear partial differential equation of fingering phenomenon has been discussed in terms of the power series using appropriate boundary conditions for any timeT>0 . The solution is in ascending power series which represents saturation of injected fluid in fingering phenomenon & its graphical and numerical presentation is given in MATLAB coding.
Mathematical Modeling Of Peristaltic Flow Of Chyme In Small Intestine, 2011 University of Texas-Pan American
Mathematical Modeling Of Peristaltic Flow Of Chyme In Small Intestine, Daniel N. Riahi, Ranadhir Roy
Applications and Applied Mathematics: An International Journal (AAM)
Mathematical models based on axisymmetric Newtonian incompressible fluid flow are studied for the peristaltic flow of chyme in the small intestines, which is an axisymmetric cylindrical tube. The flow is modeled more realistically modeled by assuming that the peristaltic rush wave is a non-periodic mode composed of two sinusoidal waves of different wavelengths, which propagate at the same speed along the outer boundary of the tube. Both cases of flow in a tube and in an annulus that are modeled and investigated in the present paper correspond respectively to the cases of flow of chyme in the small intestine in …
Transverse Waves In Simulated Liquid Rocket Engines With Arbitrary Headwall Injection, 2011 University of Tennessee, Knoxville
Transverse Waves In Simulated Liquid Rocket Engines With Arbitrary Headwall Injection, Charles Toufic Haddad
Masters Theses
This work introduces a closed-form analytical solution for the transverse vorticoacoustic wave in a circular cylinder with arbitrary headwall injection. This particular configuration mimics the conditions leading to the onset of traveling radial and tangential waves in a simple liquid rocket engine (LRE). Assuming a short cylindrical chamber with an injecting headwall, regular perturbations are used to linearize the problem’s mass, momentum, energy, ideal gas and isentropic relations. A Helmholtz decomposition is subsequently applied to the first-order disturbance equations, thus giving rise to a compressible, inviscid and acoustic set that is responsible for driving the unsteady motion and to an …
Convection Due To Spatially Distributed Heating, 2011 The University of Western Ontario
Convection Due To Spatially Distributed Heating, Mohammad Zakir Hossain
Electronic Thesis and Dissertation Repository
Convection in an infinite horizontal slot subject to spatially distributed heating has been investigated for a wide range of Prandtl numbers. The primary flow response consists of convection in the form of rolls. When heating wave number alpha is sufficiently large the convection is found to be limited to a layer adjacent to lower wall and a uniform conductive layer emerges at upper section of the slot.
Conditions leading to the emergence of secondary convection have been identified using linear stability of the above primary convection. The secondary convection gives rise to longitudinal, or transverse, or oblique rolls; or to …
Nonlinear Progressive Wave Equation For Stratified Atmospheres, 2011 Naval Research Laboratory
Nonlinear Progressive Wave Equation For Stratified Atmospheres, B. Edward Mcdonald, Andrew A. Piacsek
All Faculty Scholarship for the College of the Sciences
The nonlinear progressive wave equation (NPE) [McDonald and Kuperman, J. Acoust. Soc. Am. 81, 1406–1417 (1987)] is expressed in a form to accommodate changes in the ambient atmospheric density, pressure, and sound speed as the time-stepping computational window moves along a path possibly traversing significant altitude differences (in pressure scale heights). The modification is accomplished by the addition of a stratification term related to that derived in the 1970s for linear range-stepping calculations and later adopted into Khokhlov-Zabolotskaya-Kuznetsov-type nonlinear models. The modified NPE is shown to preserve acoustic energy in a ray tube and yields analytic similarity solutions for …
Mass Flow Through Solid 4he Induced By The Fountain Effect, 2011 University of Massachusetts - Amherst
Mass Flow Through Solid 4he Induced By The Fountain Effect, M. W. Ray, Robert B. Hallock
Robert Hallock
Using an apparatus that allows superfluid liquid 4_He to be in contact with hcp solid 4_He at pressures greater than the bulk melting pressure of the solid, we have performed experiments that show evidence for 4_He mass flux through the solid and the likely presence of superfluid inside the solid. We present results that show that a thermomechanical equilibrium in quantitative agreement with the fountain effect exists between two liquid reservoirs connected to each other through two superfluid-filled Vycor rods in series with a chamber filled with solid〖 4〗_He. We use the thermomechanical effect to induce flow through the solid …
Left Ventricular Assist Devices: Engineering Design Considerations, 2011 University of Central Florida
Left Ventricular Assist Devices: Engineering Design Considerations, Marwan A. Simaan, Eduardo Divo, George Faragallah, Yu Wang
Publications
Patients with end-stage congestive heart failure awaiting heart transplantation often wait long periods of time (300 days or more on the average) before a suitable donor heart becomes available. The medical community has placed increased emphasis on the use of Left Ventricular Assist Devices or LVADs that can substitute for, or enhance, the function of the natural heart while the patient is waiting for the heart transplant (Poirier, 1997; Frazier & Myers, 1999). Essentially, a rotary LVAD is a pump that operates continuously directing blood from the left ventricle into the aorta by avoiding the aortic valve. Generally speaking, the …
Positron Emission Tomography (Pet) For Flow Measurement, 2011 University of Tennessee, Knoxville
Positron Emission Tomography (Pet) For Flow Measurement, Bi Yao Zhang
Masters Theses
Positron Emission Tomography (PET) is frequently used for medical imaging. Maturity and flexibility of PET as an imaging technique has expanded its utility beyond the medical domain. It can be used as a tool for fluid flow studies in opaque fluids and for flow within complex geometry where conventional optical flow measurement approaches fail. This study explores the capabilities of PET as flow measurement tool suited to validation of computational fluid dynamic (CFD) predictions.
The MicroPET P4 scanner was used to image the diffusion process in flow around a rod bundle geometry similar to that found in a nuclear reactor …
Turbulence And Wave Dynamics Across Gas–Liquid Interfaces, 2011 Embry-Riddle Aeronautical University
Turbulence And Wave Dynamics Across Gas–Liquid Interfaces, Shahrdad Sajjadi, Julian Hunt, Stephen Belcher, Derek Stretch, John Clegg
Publications
Mechanisms are reviewed here for the distortion of turbulent flows near thin density interfaces and their effects on transfer processes across them. Firstly the results of rapid distortion calculations show how the in homogeneous eddy structure depends on whether the turbulence is generated above or below the interface, or in both regions. The flow is unstratified and the buoyancy forces are stable and strong enough relative to the inertial forces that the interface is continuous. It is shown that as the surface blocks the vertical turbulent eddy motions, horizontal straining motions are induced which affect the surface viscous layers and …
Ferrofluids, 2011 California Polytechnic State University - San Luis Obispo
Ferrofluids, James Patt
Physics
Ferrofluids are truly fascinating. Technologically savvy artists have been able to capture the human imagination with little but a judicious application of a magnetic field. The substance seems to defy gravity, flowing and shaping itself seemingly like magic (see Figure 1). The true magic, however, is the vast range of properties that this intrinsically simple substance can exhibit. It can vary its viscosity given the strength of the magnetic field. It can draw heat away from an over worked mechanical component. It can even split a beam of light in two. It’s hard to imagine what kind of strange and …
Analysis Of Flow Fields In A Flexible Tube With Periodic Constriction, 2011 The University of Burdwan
Analysis Of Flow Fields In A Flexible Tube With Periodic Constriction, Swati Mukhopadhyay, Prativa R. De, Mani S. Mandal, G. C. Layek
Applications and Applied Mathematics: An International Journal (AAM)
Numerical techniques based on pressure-velocity formulation have been adopted to solve approximately, the governing equations for viscous flows through a tube (simulating an artery) with a periodic constriction. The effect of the constriction as well as the rigid of the tube, on the flow characteristics, and its consequences for arterial disease is the focus of this investigation. The unsteady incompressible Navier-Stokes equations are solved by using the finite-difference technique in staggered grid distribution. The haemodynamic factors like wall shear stress, pressure and velocity are analyzed through their graphical representations. Maximum resistance is attained in case of rigid stenosed tube rather …
Human Powered Helicopter: Observing The Impacts Of Ground Effect And Intermeshed Rotors, 2011 California Polytechnic State University - San Luis Obispo
Human Powered Helicopter: Observing The Impacts Of Ground Effect And Intermeshed Rotors, Shane Stowe
Physics
No abstract provided.