Physical Sciences and Mathematics Commons^™

Wave Motion Induced By Turbulent Shear Flows Over Growing Stokes Waves, Shahrdad Sajjadi, Serena Robertson, Rebecca Harvey, Mary Brown

Publications

The recent analytical of multi-layer analyses proposed by Sajjadi et al. (J Eng Math 84:73, 2014) (SHD14 therein) is solved numerically for atmospheric turbulent shear flows blowing over growing (or unsteady) Stokes (bimodal) water waves, of low-to-moderate steepness. For unsteady surface waves, the amplitude a(t)∝ekcita(t)∝ekcit, where kcikci is the wave growth factor, k is the wavenumber, and cici is the complex part of the wave phase speed, and thus, the waves begin to grow as more energy is transferred to them by the wind. This will then display the critical height to a point, where the thickness of the inner …

Roles Of Siphon Flows In Suspension Feeding, Kevin Du Clos

Electronic Theses and Dissertations

Benthic marine suspension feeders provide an important link between benthic and pelagic ecosystems. The strength of this link is determined by suspension-feeding rates. Many studies have measured suspension-feeding rates using indirect clearance-rate methods, which are based on the depletion of suspended particles. Direct methods that measure the flow of water itself are less common, but they can be more broadly applied because clearance-rate measurements are affected by properties of the cleared particles. We present pumping rates for three species of suspension feeders, the clams Mya arenaria and Mercenaria mercenaria and the tunicate Ciona intestinalis, calculated using a direct method …

Large Scale Brownian Dynamics Simulation Of Dilute And Semidilute Polymeric Solutions, Amir Saadat

Doctoral Dissertations

Excluded Volume (EV) and Hydrodynamic Interactions (HI) play a central role in static and dynamic properties of macromolecules in solution under equilibrium and nonequilibrium settings. The computational cost of incorporating HI in mesoscale Brownian dynamics (BD) simulations, particularly in the semidilute regime has motivated significant research aimed at development of high-fidelity and efficient techniques.

In this study, I have developed several algorithms for the mesoscale bead-spring representation of a macromolecular solution in dilute and semidilute regimes. The Krylov subspace method enables fast calculation of single chain dynamics with simulation time scaling of O(N_b²) [order N …

Dispersion Characteristics Of Non-Newtonian Fluid During Transportation Of Nanoparticles In Permeable Capillary, Rekha Bali, Nivedita Gupta, Swati Mishra

Applications and Applied Mathematics: An International Journal (AAM)

The present analysis deals with the dispersion characteristics of blood described as Herschel- Bulkley fluid in capillary with permeable walls for fluid and impermeable for the nanoparticles. The contribution of molecular and convective diffusion is recalled from the Taylor and Aris coefficient of diffusion. The effective longitudinal diffusion depends on three parameters namely rheological parameter, pressure parameter, and the permeability parameter. We investigate the influence of the longitudinal transport of nanoparticles with permeable blood vessels on the effective dispersion. It shows that the effective diffusion of nanoparticles reduces with increase in radius of the plug region (i.e., the volume of …

Analysis Of Groundwater Contaminants Using Aris Dispersion Model, Nirmala P. Ratchagar, S. Senthamilselvi

Applications and Applied Mathematics: An International Journal (AAM)

The paper presents the study of dispersion of contaminants in unsteady laminar flow of an incompressible fluid (groundwater) bounded by an upper porous layer and lower impermeable layer with interphase mass transfer. An analytical solution of unsteady advection dispersion based on Aris-Barton method of moments is presented up to the second moment about the mean in axial direction.

Heat And Mass Transfer In Mhd Micropolar Fluid In The Presence Of Diffusion Thermo And Chemical Reaction, R. V. M.S.S Kirankumar1, V. C. C.Raju, P. D. Prasad, S. V. Varma

Applications and Applied Mathematics: An International Journal (AAM)

This work is devoted to investigating the influence of diffusion thermo effect on hydromagnetic heat and mass transfer oscillatory flow of a micropolar fluid over an infinite moving vertical permeable plate in a saturated porous medium in the presence of transverse magnetic field and chemical reaction. The dimensionless equations are solved analytically using perturbation technique. The effects of the various fluid flow parameters entering into the problem on the velocity, microrotation, temperature and concentration fields within the boundary layer are discussed with the help of graphs. Also the local skin-friction coefficient, the wall couple stress coefficient, and the rates of …

On Arresting The Complex Growth Rates In Rotatory Triply Diffusive Convection, Jyoti Prakash, Renu Bala, Kanu Vaid, Vinod Kumar

Applications and Applied Mathematics: An International Journal (AAM)

Linear stability of a triply diffusive fluid layer (one of the components may be heat) has been mathematically analyzed in the presence of uniform vertical rotation. Upper bounds for the complex growth rate of an arbitrary oscillatory perturbation of growing amplitude are derived which are important especially when at least one of the boundaries is rigid so that exact solutions in closed form are not obtainable. Further, it is proved that the results obtained herein are uniformly valid for any combination of dynamically free and rigid boundaries. It is also shown that the existing results of rotatory hydrodynamic Rayleigh Benard …

Hydromagnetic Peristaltic Transportation With Porous Medium Through An Asymmetric Vertical Tapered Channel And Joule Heating, S. R. Kumar

Applications and Applied Mathematics: An International Journal (AAM)

The present paper deals with a theoretical investigation of the hydromagnetic peristaltic transportation with porous medium through coaxial asymmetric vertical tapered channel and joule heating which has been studied under the assumption of long wavelength approximations. Exact analytical expressions of axial velocity, volume flow rate, pressure gradient, temperature and heat transfer coefficient at both walls were calculated. The effects of various emerging parameters, Hartmann number, Non-uniform parameter, Prandtl number, Heat generator parameter, Brinkman number, Porous parameter are discussed through the use of graphs. We notice from the figures that the temperature of the fluid increases in the entire vertical tapered …

Impact Of Permeable Lining Of The Wall On The Peristaltic Flow Of Herschel Bulkley Fluid, G. C. Sankad, Asha Patil

Applications and Applied Mathematics: An International Journal (AAM)

The peristaltic motion is modeled for the Herschel Bulkley fluid, considered to flow in a non-uniform inclined channel. The channel wall is supposed to be lined with a non-erodible porous material. The flow is considered to be moving in a wave frame of reference moving with same velocity as of the sinusoidal wave. Low Reynolds number and long wave length assumptions are made to solve the model. Analytical solution is obtained for the pressure difference and also for the frictional force. Graphs are plotted, using Mathematica software, for both the results of pressure difference and frictional force against time average …

Unsteady Mhd Flow Past An Impulsively Started Inclined Plate With Variable Temperature And Mass Diffusion In The Presence Of Hall Current, U. S. Rajput, Gaurav Kumar

Applications and Applied Mathematics: An International Journal (AAM)

No abstract provided.

Iterative Solution Of Fractional Diffusion Equation Modelling Anomalous Diffusion, A. Elsaid, S. Shamseldeen, S. Madkour

Applications and Applied Mathematics: An International Journal (AAM)

In this article, we study the fractional diffusion equation with spatial Riesz fractional derivative. The continuation of the solution of this fractional equation to the solution of the corresponding integer order equation is proved. The series solution is obtained based on properties of Riesz fractional derivative operator and utilizing the optimal homotopy analysis method (OHAM). Numerical simulations are presented to validate the method and to show the effect of changing the fractional derivative parameter on the solution behavior.

On The Propagation Of Atmospheric Gravity Waves In A Non-Uniform Wind Field: Introducing A Modified Acoustic-Gravity Wave Equation, Ahmad Talaei

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Atmospheric gravity waves play fundamental roles in a broad-range of dynamical processes extending throughout the Earth’s neutral atmosphere and ionosphere. In this paper, we present a modified form for the acoustic-gravity wave equation and its dispersion relationships for a compressible and non-stationary atmosphere in hydrostatic balance. Importantly, the solutions have been achieved without the use of the well-known Boussinesq approximation which have been used extensively in previous studies.

We utilize the complete set of governing equations for a compressible atmosphere with non-uniform airflows to determine an equation for vertical velocity of possible atmospheric waves. This intricate wave equation is simplified …

Plasma Processes And Polymers Third Special Issue On Plasma And Cancer, Mounir Laroussi, Annemie Bogaerts, Nazir Barekzi

Electrical & Computer Engineering Faculty Publications

(First paragraph) This issue of Plasma Processes and Polymers is the third in a series on the applications of low temperature plasma (LTP) against cancer, or “plasma oncology.” The papers in this issue are inspired from the talks given at the third International Workshop on Plasma for Cancer Treatment (IWPCT) which took place on April 11–12, 2016 in Washington, DC, USA. IWPCT is an international workshop that was created in 2014 as a venue to share cutting edge plasma oncology research. The first IWPCT was held in Washington DC, under the co-chairmanship of Prof. Mounir Laroussi (Old Dominion University) and …

Computational Fluid Dynamics Is Key To Better Flying Aircraft, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Making Waves: A Computational Swimming Lamprey With Sensory Feedback, Christina Hamlet, Eric D. Tytell, Lisa J. Fauci, Kathleen A. Hoffman

Annual Symposium on Biomathematics and Ecology Education and Research

No abstract provided.

Interdisciplinary Undergraduate Research In Biofluids, Eva M. Strawbridge

Annual Symposium on Biomathematics and Ecology Education and Research

No abstract provided.

Dem-Cfd Numerical Simulation And Experimental Validation Of Heat Transfer And Two-Component Flow In Fluidized Bed, Feihong Guo

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Thermoelectric Magnetohydrodynamic Effects In Solidification Processes, Andrew Kao, Koulis Pericleous, Peter Lee, Biao Cai, Jianrong Gao

The 8th International Conference on Physical and Numerical Simulation of Materials Processing

No abstract provided.

Natural Convection And Forced Convection Model Based On Electroneutrality And Migration In Redox Mhd Systems, Fangping Yuan, Kakkattukuzhy M. Isaac

Collaborative Research: Actively Controllable Microfluidics with Film-Confined Redox-Magnetohydrodynamics -- Video and Data

No abstract provided.

Evaluation Of The Potential Impact On Flow And Sediment Transport From Proposed James River Crossings, Yinglong J. Zhang, Harry V. Wang, Zhuo Liu, Mac Sisson, Jian Shen

Reports

The purpose of this study is to evaluate the potential impact on flow and sedimentation potential due to the proposed new crossings on the lower James River by VDOT. This project was built upon previous effort in the same area (Boon et al. 1999); the latter used VIMS’ 3D Hydrodynamic-Sedimentation Model (HYSED) to study the impact of the bridge-tunnel infrastructure on the physical characteristics (including tides, currents, circulation, salinity and sedimentation) under the existing and alternative scenarios. Due to various limitations at that time, smaller bridge pilings were not resolved but instead parameterized. In this update study, we used an …

Puddle Jumping: Spontaneous Ejection Of Large Liquid Droplets From Hydrophobic Surfaces During Drop Tower Tests, Babek Attari, Mark M. Weislogel, Andrew Paul Wollman, Yongkang Chen, Trevor Snyder

Mechanical and Materials Engineering Faculty Publications and Presentations

Large droplets and puddles jump spontaneously from sufficiently hydrophobicsurfaces during routine drop tower tests. The simple low-cost passive mechanism can in turn be used as an experimental device to investigate dynamic droplet phenomena for drops up to 104 times larger than their normal terrestrial counterparts. We provide and/or confirm quick and qualitative design guides for such “drop shooters” as employed in drop tower tests including relationships to predict droplet ejection durations and velocities as functions of drop volume, surface texture, surface contour, wettability pattern, and fluid properties including contact angle. The latter is determined via profile image comparisons with numerical …

Development Of Ultrasonic Techniques For Characterization Of Liquid Mixtures, William A. Cooke

Electronic Thesis and Dissertation Repository

To evaluate the suitability of ultrasonic techniques for on-line process monitoring applications, an ultrasonic probe was used to measure acoustic velocity, acoustic impedance, and isentropic compressibility of hydrocarbons (including n-, iso-, and cycloalkanes, toluene, mineral oil, and crude oil) and polar liquids (alcohols, water, salt water) over a temperature range of 25-60°C. Temperature, carbon chain length, molecular shape, and intermolecular forces had significant effects on ultrasonic parameters. Relationships between media characteristics and observed ultrasonic parameters were modeled using empirical-least squares equations. The same parameters were measured in binary mixtures of hydrocarbons in heptane, as well as polar liquids in ethanol. …

Particle Swarm Transport In Porous Media, Alison R. Hoe, Laura J Pyrak-Nolte

The Summer Undergraduate Research Fellowship (SURF) Symposium

In recent years, interest in particulate transport in the subsurface has increased with the increased use of micro-particulates in consumer products. In this research, we study particulate swarm transport through porous media that depends on the complexity of the flow paths, on the size and shape of the particles and on the physical interactions among the particles, fluids, and matrix. Specifically, we investigate the effect of pore geometry and grain wettability on swarm evolution under gravity. Swarms were composed of 3 micron polystyrene beads in either water or water with KCL (%). Two types of grains are used to simulate …

A Fast Model For The Simulation Of External Gear Pumps, Zechao Lu, Xinran Zhao, Andrea Vacca

The Summer Undergraduate Research Fellowship (SURF) Symposium

External gear pump is an important category of positive displacement fluid machines used to perform the mechanical–hydraulic energy conversions in many fluid power applications. An efficient numerical simulation program is needed to simulate the system in order to provide a direction for design purpose. The model consists of a lumped parameter fluid dynamic model and a model that simulates the radial micro-motions of the gear’s axes of rotation. The system consists of a set of ordinary differential equations related to the conservation on mass of the internal control volumes of the pump, which are given by the tooth space volumes …

Deceleration Of Droplets That Glide Along The Free Surface Of A Bath, Jacob Hale, Caleb Akers

Physics & Astronomy Faculty publications

A droplet obliquely impacting a bath surface of the same fluid can traverse along the interface while slowing at an exponential rate. The droplet rests on a thin film of air and deforms the bath surface creating a dimple and travels along the surface similar to a wave pulse. Viscous coupling of the droplet and bath surfaces through the air film leads to viscous drag on the bath and perturbs the wave motion of the otherwise free surface. Even though Reynolds numbers are greater than unity (Re O(10 -- 100)), we show that the droplet's deceleration is only due to …

Growth Of Groups Of Wind Generated Waves, Frederique Drullion, Shahrdad Sajjadi

Publications

In this paper we demonstrate numerical computations of turbulent wind blowing over group of waves that are growing in time. The numerical model adopted for the turbulence model is based on differential second-moment model that was adopted for growing idealized waves by Drullion & Sajjadi (2014). The results obtained here demonstrate the formation of cat's-eye which appear asymmetrically over the waves within a group.

Growth Of Unsteady Wave Groups By Shear Flows, Shahrdad Sajjadi, Julian Hunt, Frederique Drullion

Publications

A weakly nonlinear theory has been proposed and developed for calculating the energy- transfer rate to individual waves in a group. It is shown what portion of total energy- transfer rate, over the envelope of wave group, affects individual waves in the group. From this an expression for complex phase speed of individual waves is calculated. It is deduced that each wave in a group does not grow at the same rate. It is shown that the critical layer is no longer symmetrical compared with the ideal monochromatic waves. This asymmetry causes the critical layer height to be lower over …

Chaotic Advection-Driven Mixing In Unsteady Three-Dimensional Mhd Flows In Microfluidic Devices, Fangping Yuan, Kakkattukuzhy M. Isaac

Collaborative Research: Actively Controllable Microfluidics with Film-Confined Redox-Magnetohydrodynamics -- Video and Data

No abstract provided.

Large Length Scale Capillary Fluidics: From Jumping Bubbles To Drinking In Space, Andrew Paul Wollman

Dissertations and Theses

In orbit, finding the "bottom" of your coffee cup is a non-trivial task. Subtle forces often masked by gravity influence the containment and transport of fluids aboard spacecraft, often in surprising non-intuitive ways. Terrestrial experience with capillary forces is typically relegated to the micro-scale, but engineering community exposure to large length scale capillary fluidics critical to spacecraft fluid management design is low indeed. Low-cost drop towers and fast-to-flight International Space Station (ISS) experiments are increasing designer exposure to this fresh field of study. This work first provides a wide variety of drop tower tests that demonstrate fundamental and applied capillary …

Approximate Analytical Solution Of Boussinesq Equation In Homogeneous Medium With Leaky Base, Rajeev K. Bansal

Applications and Applied Mathematics: An International Journal (AAM)

Approximate analytical solutions of Boussinesq equation are widely used for approximation of subsurface seepage flow in confined and unconfined aquifers under varying hydrological conditions. In this paper, we use a 2-dimensional linearized Boussinesq equation to simulate the water table fluctuations in an isotropic aquifer overlying a semi pervious bed under multiple localized recharge and withdrawal. The unconfined aquifer is considered to be in contact with two water bodies of constant water head along opposite cost lines, while the remaining two faces have no flow condition. The mathematical model is solved analytically using finite Fourier sine transform and the application of …