Fluid Dynamics Commons^™

Nonlinear Waves, Instabilities And Singularities In Plasma And Hydrodynamics, Denis Albertovich Silantyev

Mathematics & Statistics ETDs

This work concentrates on Langmuir wave filamentation instability in the kinetic regime of plasma and computation of Stokes wave with high precision using conformal maps.

Nonlinear effects are present in almost every area of science as soon as one tries to go beyond the first order approximation. In particular, nonlinear waves emerge in such areas as hydrodynamics, nonlinear optics, plasma physics, quantum physics, etc. The results of this work are related to nonlinear waves in two areas, plasma physics and hydrodynamics, united by concepts of instability, singularity and advanced numerical methods used for their investigation.

The first part of this …

A Mathematical Model And Numerical Simulations Of Redox Electrochemical Systems With Mhd And Natural Convection, Kakkattukuzhy M. Isaac, Fangping Yuan

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

A comprehensive mathematical model for redox electrochemical systems with magnetohydrodynamics (MHD) and natural convection are presented. The model is based on density changes in isothermal systems that accompany redox reaction at the electrode due to supporting electrolyte ions migrating into and out of the diffusion layer to satisfy electroneutrality. Numerical simulations have been performed for an axisymmetric, milli-electrode electrochemical cell with gravity directed along the axis in both directions to investigate the effect of the electrode orientation with respect to gravity. Results show that natural convection is significant in both cases, with the maximum velocity being an order of magnitude …

Evaluation And Enhancement Of Clean Energy Systems: Analytical, Computational And Experimental Study Of Solar And Nuclear Cycles, Nima Fathi

Mechanical Engineering ETDs

Clean (and specifically renewable) energy is steadily improving its global share. However, finite availability of fossil fuels and the growing effects of climate change make it an urgent priority to convince the industry and governments to incentivize investment in the renewable energy field and to make it more attractive by decreasing the capital cost. Until recently, uncertainties in funding limited renewable energy development, especially in the US. That limitation has been one of the barriers to progress. Another limitation of many renewable energy systems is the variability in their output, which makes them unsuitable for baseline power production. Therefore, fossil …

Instrument Design Optimization With Computational Methods, Michael H. Moore

Physics Theses & Dissertations

Using Finite Element Analysis to approximate the solution of differential equations, two different instruments in experimental Hall C at the Thomas Jefferson National Accelerator Facility are analyzed. The time dependence of density fluctuations from the liquid hydrogen (LH2) target used in the Q_weak experiment (2011-2012) are studied with Computational Fluid Dynamics (CFD) and the simulation results compared to data from the experiment. The 2.5 kW liquid hydrogen target was the highest power LH2 target in the world and the first to be designed with CFD at Jefferson Lab. The first complete magnetic field simulation of the Super High Momentum …

Natural Convection In Redox Electrochemistry: Model, Simulation And Experiments, Fangping Yuan, Kakkattukuzhy M. Isaac

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

No abstract provided.

Effect Of Nonlinear Thermal Radiation On Mhd Chemically Reacting Maxwell Fluid Flow Past A Linearly Stretching Sheet, A. M. Ramireddy, J. V. Ramana Reddy, N. Sandeep, V. Sugunamma

Applications and Applied Mathematics: An International Journal (AAM)

This communication addresses the influence of nonlinear thermal radiation on magneto hydrodynamic Maxwell fluid flow past a linearly stretching surface with heat and mass transfer. The effects of heat generation/absorption and chemical reaction are taken into account. At first, we converted the governing partial differential equations into nonlinear ordinary differential equations with the help of suitable similarity transformations and solved by using Runge-Kutta based shooting technique. Further, the effects of various physical parameters on velocity, temperature and concentration fields were discussed thoroughly with the help of graphs obtained by using bvp5c MATLAB package. In view of many engineering applications we …

Analysis Of Heat And Mass Transfer Of An Inclined Magnetic Field Pressure-Driven Flow Past A Permeable Plate, M. S. Dada, S. O. Salawu

Applications and Applied Mathematics: An International Journal (AAM)

The study considers heat and mass transfer of magnetohydrodynamics pressure-driven flow passed a stretching permeable surface in the presence of inclined uniform magnetic field. The equations governing the model are transformed by Lie’s group and solved using weighted residual method. The results obtained are compared with that of fourth order Runge-Kutta method that show the effects of Skin friction, Nusselt and Sherwood numbers on the flow. Finally, the influence of some important parameters on the flow are presented graphically and discussed.

Effect Of Buoyancy And Magnetic Field On Unsteady Convective Diusion Of Solute In A Boussinesq Stokes Suspension Bounded By Porous Beds, Nirmala P. Ratchagar, R. Vijayakumar

Applications and Applied Mathematics: An International Journal (AAM)

Hydromagnetic free and forced convection in a parallel plate channel bounded by porous bed and transverse magnetic field has been considered. When there is a uniform axial temperature variation along the walls, the primary flow shows incipient flow reversal at the upper plate for an increase in temperature along that plate. Similarly flow reversal at the lower plate occurs with a decrease in temperature along that plate. The magnetic field, arising as a body couple in the governing equations is shown to increase the axis dispersion coefficient. The effect of various physical parameters such as Hartmann number, Grashof number, porous …

Numerical Solution Of Fractional Integro-Differential Equations With Nonlocal Conditions, M. Jani, D. Bhatta, S. Javadi

Applications and Applied Mathematics: An International Journal (AAM)

In this paper, we present a numerical method for solving fractional integro-differential equations with nonlocal boundary conditions using Bernstein polynomials. Some theoretical considerations regarding fractional order derivatives of Bernstein polynomials are discussed. The error analysis is carried out and supported with some numerical examples. It is shown that the method is simple and accurate for the given problem.

Hematocrit Level On Blood Flow Through A Stenosed Artery With Permeable Wall: A Theoretical Study, A. Malek, A. Hoque

Applications and Applied Mathematics: An International Journal (AAM)

The paper deals with the hematocrit level on resistance of flow, wall shear stress in a stenosed artery of permeable wall. In the paper we have developed and solved some theoretical formulas based on stenosis and hematocrit effects. The results highlight that the resistance of flow increases for increasing of stenosis height where the hematocrit level (35%-45%) has significant effects. Moreover, the effects of slip parameter and Darcy number due to permeability of the wall on resistance of flow have been investigated. The effects of hematocrit level, slip parameter and Darcy number have been focused on wall shear stress of …

Characterization Of The Shock Wave Structure In Water, Emilie Teitz

Master's Theses (2009 -)

The scientific community is interested in furthering the understanding of shock wave structures in water, given its implications in a wide range of applications; from researching how shock waves penetrate unwanted body tissues to studying how humans respond to blast waves. Shock wave research on water has existed for over five decades. Previous studies have investigated the shock response of water at pressures ranging from 1 to 70 GPa using flyer plate experiments. This report differs from previously published experiments in that the water was loaded to shock pressures ranging from 0.36 to 0.70 GPa. The experiment also utilized tap …

An Rbf Interpolation Blending Scheme For Effective Shock-Capturing, M. Harris, Eduardo Divo, Alain J. Kassab

Publications

In recent years significant focus has been given to the study of Radial basis functions (RBF), especially in their use on solving partial differential equations (PDE). RBF have an impressive capability of inter- polating scattered data, even when this data presents localized discontinuities. However, for infinitely smooth RBF such as the Multiquadrics, inverse Multiquadrics, and Gaussian, the shape parameter must be chosen properly to obtain accurate approximations while avoiding ill-conditioning of the interpolating matrices. The optimum shape parameter can vary significantly depending on the field, particularly in locations of steep gradients, shocks, or discontinuities. Typically, the shape parameter is chosen …

A Coupled Localized Rbf Meshless/Drbem Formulation For Accurate Modeling Of Incompressible Fluid Flows, Leonardo Bueno, Eduardo Divo, Alain J. Kassab

Publications

Velocity-pressure coupling schemes for the solution of incompressible fluid flow problems in Computational Fluid Dynamics (CFD) rely on the formulation of Poisson-like equations through projection methods. The solution of these Poisson-like equations represent the pressure correction and the velocity correction to ensure proper satisfaction of the conservation of mass equation at each step of a time-marching scheme or at each level of an iteration process. Inaccurate solutions of these Poisson-like equations result in meaningless instantaneous or intermediate approximations that do not represent the proper time-accurate behavior of the flow. The fact that these equations must be solved to convergence at …

An Experimental Investigation Of Wing-Tip Vortex Decay In Turbulence, Hai G. Ghimire, Sean C. C. Bailey

Mechanical Engineering Faculty Publications

Particle image velocimetry measurements were conducted for a wing-tip vortex decaying in free-stream turbulence. The vortex exhibited stochastic collapse with free-stream turbulence present, with the breakdown initiating earlier for higher levels of turbulence. An increased rate of decay of the vortex tangential velocity was also observed, increasing with increasing free-stream turbulence. The decay of the vortex tangential velocity without the free-stream turbulence was well represented by viscous diffusion, resulting in an increase in the core radius and decrease in the peak tangential velocity. With the addition of free-stream turbulence, the rate of decay of the peak tangential velocity of the …

Optimizing Jets For Wake Control Of Ground Vehicles, Domenic Barsotti, Sandra Boetcher

Publications

A system of wake control for a ground vehicle to help promote increased fuel efficiencies of the ground vehicle by modifying an air flow wake generated during the movement of the vehicle in a forward direction. The system includes at least one slot jet configured to be located along a rear profile portion of the ground vehicle. The at least one slot jet is configured to provide a continuous flow of air at a non-zero velocity when the ground vehicle is moving in a forward direction, the non-zero velocity being at least partially directed in a rearward direction with an …

Multi-Stage Axial Compressor With Counter-Rotation, Vinod Gehlot, Magdy S. Attia, Divyam Garg

Publications

A multi-stage axial compressor incorporating a counter-rotational movement is provided with a series of rotors mounted along and driven by a driveshaft, and a geared counter-rotating outer casing. A planetary gear system is assembled along a static casing, which can be assembled as a forward or aft casing for the compressor. The bearings of the planetary gear system typically will be aligned concentrically with a center rotor drum assembly mounted along the single driveshaft. The counter-rotating drum assembly will be assembled over the rotor drum assembly and will be engaged by the forward and aft casings so as to provide …

A Physics-Based Approach To Modeling Wildland Fire Spread Through Porous Fuel Beds, Tingting Tang

Theses and Dissertations--Mechanical and Aerospace Engineering

Wildfires are becoming increasingly erratic nowadays at least in part because of climate change. CFD (computational fluid dynamics)-based models with the potential of simulating extreme behaviors are gaining increasing attention as a means to predict such behavior in order to aid firefighting efforts. This dissertation describes a wildfire model based on the current understanding of wildfire physics. The model includes physics of turbulence, inhomogeneous porous fuel beds, heat release, ignition, and firebrands. A discrete dynamical system for flow in porous media is derived and incorporated into the subgrid-scale model for synthetic-velocity large-eddy simulation (LES), and a general porosity-permeability model is …

The Intrinsic Variability Of The Water Vapor Saturation Ratio Due To Mixing, Jesse Anderson

Dissertations, Master's Theses and Master's Reports

The water vapor concentration plays an important role for many atmospheric processes. The mean concentration is key to understand water vapor's effect on the climate as a greenhouse gas. The fluctuations about the mean are important to understand heat fluxes between Earth's surface and the boundary layer. These fluctuations are linked to turbulence that is present in the boundary layer. Turbulent conditions are simulated in Michigan Tech’s multiphase, turbulent reaction chamber, the π chamber. Measurements for temperature and water vapor concentration were recorded under forced Rayleigh- Bénard convection at several turbulent intensities. These were used to calculate the saturation ratio, …

Exploiting Modern Image Processing In Surface Flow Visualisation, Tarek Ihab Abdelsalam, Richard Williams, Grant Ingram

Mechanical Engineering

Surface flow visualisation is an experimental technique where the surface of interest is painted with an oil and dye mixture before a flow is applied to the object. In regions of high shear stress the oil/dye mixture is then removed and in regions of low shear stress the oil/dye mixture stays or builds up. The resulting pattern can be analysed to determine the structure near the surface under test, this is normally done in a qualitative manner with flow structures being identified based on the expertise of the experimentalist. Modern image processing tools can identify shapes and lines in pictures …

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 …

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 …

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 …

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 …

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.

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 …

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

Aviation Department Publications

No abstract provided.

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.

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 …

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 …