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Full-Text Articles in Fluid Dynamics
Characterizing Nanoparticle Size By Dynamic Light Scattering, M. Zaman, S. Ang, S. Singh
Characterizing Nanoparticle Size By Dynamic Light Scattering, M. Zaman, S. Ang, S. Singh
Journal of the Arkansas Academy of Science
The Dynamic Light Scattering (DLS) Technique was used to determine the size, shape and diffusion coefficient of rod-like nanoparticles. The intensity auto-correlation functions of light scattered by particles in a solution were measured and analyzed to obtain the relaxation rates for decay of intensity correlations. These decay rates are related to the diffusion coefficients pertaining to the motion of the particle. In the case of nanorods, there are two types of motion - translational and rotational. By disentangling the relaxation rates, corresponding to these two types of motion, the shape and size of nanoparticles were characterized. These experiments, though limited …
Electron Shock Waves With A Large Current Behind The Shock Front, H. D. Newberry, M. Hemmati, H. D. Moore, K. Ledbetter, M. W. Bowman
Electron Shock Waves With A Large Current Behind The Shock Front, H. D. Newberry, M. Hemmati, H. D. Moore, K. Ledbetter, M. W. Bowman
Journal of the Arkansas Academy of Science
The propagation of breakdown waves in a gas, which is primarily driven by electron gas pressure, is described by a one-dimensional, steady-state, three-component (electrons, ions, and neutral particles) fluid model. We consider the electron gas partial pressure to be much larger than that of the other species and the waves to have a shock front. Our set of equations consists of the equations of conservation of the flux of mass, momentum, and energy coupled with Poisson’s equation. This set of equations is referred to as the electron fluid dynamical equations. In this study we are considering breakdown waves propagating in …
Boundary Condition On Electron Temperature For Antiforce Current Bearing Waves, M. Hemmati, W. P. Childs, D. C. Waters, J. D. Counts, J. K. Schmitt
Boundary Condition On Electron Temperature For Antiforce Current Bearing Waves, M. Hemmati, W. P. Childs, D. C. Waters, J. D. Counts, J. K. Schmitt
Journal of the Arkansas Academy of Science
In our investigation of breakdown waves, we apply a one-dimensional, three-component, steady-state fluid model. The wave is considered to be shock fronted and the electrons are assumed to be the main element in propagation of the wave. In our fluid model, the electron gas temperature is assumed to be large enough to sustain the wave motion. Our set of fluid equations is composed of the equations of conservation of mass, momentum and energy plus the Poisson’s equation. This investigation involves breakdown waves for which a large current exist in the vicinity of the wave front. Existence of current behind the …
Electric Discharge: Boundary Conditions, Mostafa Hemmati, Chris Justice
Electric Discharge: Boundary Conditions, Mostafa Hemmati, Chris Justice
Journal of the Arkansas Academy of Science
The electron gas in electric discharge can be described by a set of one-dimensional fluid dynamical equations. The fundamental equations are those of a three-component (electrons, ions, and neutral particles) fluid, different from the treatment of the problem inplasma physics, a fully ionized two-component case. The leading edge of the wave is treated as a shock front driven mainly by the electron gas pressure. Integrating the one-dimensional global differential equations for mass balance, conservation of momentum and energy, and evaluating the constant of integration at the wave front permits derivation of boundary conditions on electron temperature and electron velocity. Using …
Antiforce Wave Profile For Quasi-Neutral Region, Mostafa Hemmati, Pashupati Adhikari, Jeremy Eckart, Marcus Ilbara
Antiforce Wave Profile For Quasi-Neutral Region, Mostafa Hemmati, Pashupati Adhikari, Jeremy Eckart, Marcus Ilbara
Journal of the Arkansas Academy of Science
This article will present a fluid dynamical theory for breakdown waves in which the direction of electric field force on electrons is in the opposite direction of wave propagation. We will refer to such waves as antiforce waves. The set of equations describing the model will include the equation of particle mass balance, equation of conservation of momentum, and equation of conservation of energy, coupled with Poisson's equation. This model treats the potential wave front as an electron shock wave propagating forward mainly due to the electron impact ionization. The shock front is succeeded by a thin dynamical transition region …
Wave Profile For Antiforce Class Ii Waves, Rory Roberts, Mostafa Hemmati
Wave Profile For Antiforce Class Ii Waves, Rory Roberts, Mostafa Hemmati
Journal of the Arkansas Academy of Science
Breakdown waves propagating in the opposite direction of the applied electric field force are referred to as antiforce waves. Breakdown waves moving into a pre-ionized medium are referred to as Class II waves. Using a one-dimensional, steady state, three-fluid, hydrodynamical model and considering the electrons as the main element in propagation of ionizing waves, we have derived the proper boundary conditions for antiforce waves moving into a preionized medium. Using the new boundary conditions and for several current values ahead of the wave, the set of electron fluid dynamical equations (equations of conservation of mass, momentum, and energy coupled with …
Speed Range For Breakdown Waves, Mostafa Hemmati, Eric L. George, Frances Terry
Speed Range For Breakdown Waves, Mostafa Hemmati, Eric L. George, Frances Terry
Journal of the Arkansas Academy of Science
Considering the electrons as the main element in breakdown wave propagation and using a one-dimensional, steady-state, three-fluid, hydrodynamical model, previous investigations have resulted in the completion of a set of equations for conservation of mass, momentum, and energy. We will use the terms proforce and antiforce waves, depending on whether the applied electric field force on electrons is with or against the direction of wave propagation. In the case of antiforce waves, the electron gas temperature and therefore the electron fluid pressure is assumed to be large enough to sustain the wave propagation down the discharge tube. For strong discontinuity …
Proforce Waves: The Effect Of Current Behind The Shock Front On Wave Structure, Mostafa Hemmati, Steven Young
Proforce Waves: The Effect Of Current Behind The Shock Front On Wave Structure, Mostafa Hemmati, Steven Young
Journal of the Arkansas Academy of Science
Recently, the initial boundary conditions for proforce waves with a substantial current behind the shock front have been derived. Computer solutions of the Electron Fluid Dynamical equations meet the expected boundary conditions at the end of the sheath region. This paper will compare the wave structure for proforce waves with and without current behind the shock front.
Computational Fluid Dynamics In Small Airway Models Of The Human Lung, G. Burnside, J. R. Hammersley, Rama N. Reddy, B. Catlin
Computational Fluid Dynamics In Small Airway Models Of The Human Lung, G. Burnside, J. R. Hammersley, Rama N. Reddy, B. Catlin
Journal of the Arkansas Academy of Science
The promise of gene replacement therapy for cystic fibrosis, the administration of drugs via inhalation therapy, and die deposition location of man-made airborne particulates all involve a more complete understanding of the fluid dynamics in the human lung. Flow in the larger airways may be measured through life-sized models directly, but the airways in the peripheral lung are too small and the flows are too complex to be studied in this manner. Computational models can be developed which will accurately represent both the geometric nature of the central airways and the fluid dynamics with in them. Two-dimensional and three-dimensional models …
Measurements Of The Drag On Spheres Falling Through The Air, J. G. Ross, Stephen R. Addison, N.O (Jack) Gaiser
Measurements Of The Drag On Spheres Falling Through The Air, J. G. Ross, Stephen R. Addison, N.O (Jack) Gaiser
Journal of the Arkansas Academy of Science
No abstract provided.