Fluid Dynamics Commons^™

Microscale To Mesoscale Modeling Of The Ocean Under Tropical Cyclones: Effects Of Sea Spray And Surfactants On Tropical Cyclone Intensity And Air-Sea Gas Exchange, Breanna Lynn Cain Vanderplow

All HCAS Student Capstones, Theses, and Dissertations

Tropical cyclone intensity prediction remains a challenge despite computational and observational developments because successful intensity forecasting requires implementing a multitude of atmospheric and oceanic processes. Hurricane Maria 2017 and Hurricane Dorian 2019 serve as prime examples of rapidly intensifying storms that devastated communities in the Caribbean. A lack of understanding and parameterization of crucial physics involved in tropical cyclone intensity in existing forecast models may have led to these and other forecasting errors.

Microscale physical processes at the air-sea interface are a major factor in intensification of tropical cyclones that are often unaccounted for in forecasting models since they are …

Dynamics And Scaling Of Particle Streaks In High-Reynolds-Number Turbulent Boundary Layers, Tim Berk, Filippo Coletti

Mechanical and Aerospace Engineering Faculty Publications

Inertial particles in wall-bounded turbulence are known to form streaks, but experimental evidence and predictive understanding of this phenomenon is lacking, especially in regimes relevant to atmospheric flows. We carry out wind tunnel measurements to investigate this process, characterizing the transport of microscopic particles suspended in turbulent boundary layers. The friction Reynolds number Re_𝜏 = O(10⁴) allows for significant scale separation and the emergence of large-scale motions, while the range of viscous Stokes number St⁺ = 18–870 is relevant to the transport of dust and fine sand in the atmospheric surface layer. We …

A Comparative Study On The Rheological Properties Of Upper Convected Maxwell Fluid Along A Permeable Stretched Sheet, Sara I. Abdelsalam, W. Abbas, A. M. Megahed, A. M. Said

Basic Science Engineering

The objective of this paper is to examine the flow of a non-Newtonian Maxwell fluid induced by a permeable stretching sheet in motion within a porous medium. The research incorporates the Cattaneo-Christov heat flux model to study the heat transfer process. The utilization of the Cattaneo-Christov heat flux approach becomes relevant in scenarios involving materials with high thermal conductivity or during short time intervals. Consequently, the current investigation holds significant importance. It is assumed that the viscosity of the Maxwell fluid changes exponentially as the temperature changes. The modeling of the physical phenomena being investigated takes into account the effects …

Modeling Single And Multiple Pacemaker Interaction In Jellyfish Locomotion, Alexander Hoover

Annual Symposium on Biomathematics and Ecology Education and Research

No abstract provided.

Faster, Cheaper, And Better Cfd: A Case For Machine Learning To Augment Reynolds-Averaged Navier-Stokes, John Peter Romano Ii

Mechanical & Aerospace Engineering Theses & Dissertations

In recent years, the field of machine learning (ML) has made significant advances, particularly through applying deep learning (DL) algorithms and artificial intelligence (AI). The literature shows several ways that ML may enhance the power of computational fluid dynamics (CFD) to improve its solution accuracy, reduce the needed computational resources and reduce overall simulation cost. ML techniques have also expanded the understanding of underlying flow physics and improved data capture from experimental fluid dynamics.

This dissertation presents an in-depth literature review and discusses ways the field of fluid dynamics has leveraged ML modeling to date. The author selects and describes …

The Role Of Nanofluids In Renewable Energy Engineering, M. M. Bhatti, K. Vafai, Sara I. Abdelsalam

Basic Science Engineering

No abstract provided.

Bacterial Motion And Spread In Porous Environments, Yasser Almoteri

Dissertations

Micro-swimmers are ubiquitous in nature from soil and water to mammalian bodies and even many technological processes. Common known examples are microbes such as bacteria, micro-algae and micro-plankton, cells such as spermatozoa and organisms such as nematodes. These swimmers live and have evolved in multiplex environments and complex flows in the presence of other swimmers and types, inert particles and fibers, interfaces and non-trivial confinements and more. Understanding the locomotion and interactions of these individual micro-swimmers in such impure viscous fluids is crucial to understanding the emergent dynamics of such complex systems, and to further enabling us to control and …

Fluid Dynamics Of Interacting Particles: Bouncing Droplets And Colloid-Polymer Mixtures, Lauren Barnes

Dissertations

Interacting particles are a common theme across various physical systems, particularly on the atomic and sub-atomic scales. While these particles cannot be seen with the human eye, insight into such systems can be gained by observing macroscopic systems whose physical behavior is similar. This dissertation consists of three different chapters, each presenting a different problem related to interacting particles, as follows:

Chapter 1 explores chaotic trajectories of a droplet bouncing on the surface of a vertically vibrating fluid bath, with a simple harmonic force acting on the droplet. The bouncing droplet system has attracted recent interest because it exhibits behaviors …

Boundary Integral Equation Methods For Superhydrophobic Flow And Integrated Photonics, Kosuke Sugita

Dissertations

This dissertation presents fast integral equation methods (FIEMs) for solving two important problems encountered in practical engineering applications.

The first problem involves the mixed boundary value problem in two-dimensional Stokes flow, which appears commonly in computational fluid mechanics. This problem is particularly relevant to the design of microfluidic devices, especially those involving superhydrophobic (SH) flows over surfaces made of composite solid materials with alternating solid portions, grooves, or air pockets, leading to enhanced slip.

The second problem addresses waveguide devices in two dimensions, governed by the Helmholtz equation with Dirichlet conditions imposed on the boundary. This problem serves as a …

Variable Resolution Smoothed Particle Hydrodynamics Schemes For 2-D And 3-D Viscous Flows, Francesco Ricci

Dissertations

Smoothed Particle Hydrodynamics (SPH) is a Lagrangian particle-based method for the numerical solution of the partial differential equations that govern the motion of fluids. The main aim of this thesis work is to better enable the applicability of SPH to problems involving multi-scale fluid dynamics. In the first part of the thesis, the capability of the SPH method to simulate three-dimensional isotropic turbulence is investigated with a detailed comparison of Lagrangian and Eulerian SPH formulations. The main reason for this first investigation is to provide an assessment of the error introduced by the particle disorder on the SPH discrete operators …

Climate Of A Cave Laboratory Representative For Rock Art Caves In The Vézère Area (South-West France), Delphine Lacanette, Léna Bassel, Fabien Salmon, Jean-Christophe Portais, Bruno Bousquet, Rémy Chapoulie, Faten Ammari, Philippe Malaurent, Catherine Ferrier

International Journal of Speleology

Leye Cave (Dordogne, France) is a laboratory cave in the Vézère area, a region that contains some of the most famous rock art caves in the world such as Lascaux, Font-de-Gaume and Combarelles, and is listed as Human World Heritage by UNESCO. Leye Cave was selected because it is representative of painted caves, with respect to parameters such as its geological stage, the presence of water and carbon dioxide, the geological state of its walls, and the size of the cave. These wall states are studied to better understand the conditions of conservation of rock art caves without damaging them. …

Optimization Of Flagellar Locomotion In The Low Reynolds Number Regime, Aidan M. Trodden, Aidan M. Trodden

Physics

This report investigates the computational and theoretical techniques - modeled by E. Lauga and C. Eloy - used to optimize the shape of an activated flagellum for enhanced cell motility. Cell motility is ubiquitous and has a large affect on biological systems such as marine life ecosystems, reproduction, and infection. The physical principles governing flagellar propulsion are explored using computational fluid dynamics simulations, mathematical modeling, and the sequential quadratic programming (SQP) optimization algorithm. Through iterative refinement, we can identify optimized flagellar shapes that would minimize the energetic cost dependent on a single dimensionless sperm numbers (Sp). The computation of the …

Diffusion-Driven Aggregation Of Particles In Quasi-2d Membranes, Oscar Gullickson Rausis

Physics

Many biological membranes can be modeled as two-dimensional (2D) viscous fluid sheets surrounded by three-dimensional (3D) fluids of different viscosity. Such membranes are dubbed quasi-2D as they exhibit properties of both 2D and 3D fluids. The Saffman length is a parameter that describes the energy exchange between the membrane and bulk fluids and controls the cross-over from 2D to 3D hydrodynamics. We aim to model diffusion-driven aggregation of particles embedded in a quasi-2D membrane. It is known that hydrodynamic interactions between solute particles significantly reduce their aggregation rate in 3D fluids. It is expected that in quasi-2D membranes the reduction …

Hydrodynamic And Physicochemical Interactions Between An Active Janus Particle And An Inactive Particle, Jessica S. Rosenberg

Dissertations, Theses, and Capstone Projects

Active matter is an area of soft matter science in which units consume energy and turn it into autonomous motion. Groups of these units – whether flocks of birds, bacterial colonies, or even collections of synthetically-made active particles – may exhibit complex behavior on large scales. While the large-scale picture is of great importance, so is the microscopic scale. Studying the individual particles that make up active matter will allow us to understand how they move, and whether and under what circumstances their activity can be controlled.

Here we delve into the world of active matter by studying colloidal-sized (100 …

Importance Of Vegetation In Tsunami Mitigation: Evidence From Large Eddy Simulations With Fluid-Structure Interactions, Abhishek Mukherjee

Dissertations

Communities worldwide are increasingly interested in nature-based solutions like coastal forests for the mitigation of coastal risks. Still, it remains unclear how much protective benefit vegetation provides, particularly in the limit of highly energetic flows after tsunami impact. The present thesis, using a three-dimensional incompressible computational fluid dynamics model with a fluid-structure interaction approach, aims to quantify how energy reflection and dissipation vary with different degrees of rigidity and vegetation density of a coastal forest.

In this study, tree trunks are represented as cylinders, and the elastic modulus of hardwood trees such as pine or oak is used to characterize …

Assorted Kerosene-Based Nanofluid Across A Dual-Zone Vertical Annulus With Electroosmosis, Sara I. Abdelsalam, A. M. Alsharif, Y. Abd Elmaboud, A. I. Abdellateef

Basic Science Engineering

The goal of this numerical simulation is to visualize the electroosmotic flow of immiscible fluids through a porous medium in vertical annular microtubes. The inner region (Region I) is filled with an electrically conducting hybrid nanofluid while an electrically conducting Jeffrey fluid is flowing in the second region (Region II). The chosen nanofluid is kerosene-based and the nanoparticles (Fe3O4-TiO2) are of a spherical shape. A strong zeta potential is taken into account and the electroosmotic velocity in the two layers is considered too. The annular microtubes are subjected to an external magnetic field and an electric field. The linked nonlinear …

U-No: U-Shaped Neural Operators, Md Ashiqur Rahman, Zachary E Ross, Kamyar Azizzadenesheli

Department of Computer Science Faculty Publications

Neural operators generalize classical neural networks to maps between infinite-dimensional spaces, e.g., function spaces. Prior works on neural operators proposed a series of novel methods to learn such maps and demonstrated unprecedented success in learning solution operators of partial differential equations. Due to their close proximity to fully connected architectures, these models mainly suffer from high memory usage and are generally limited to shallow deep learning models. In this paper, we propose U-shaped Neural Operator (U-NO), a U-shaped memory enhanced architecture that allows for deeper neural operators. U-NOs exploit the problem structures in function predictions and demonstrate fast training, data …

Monolithic Multiphysics Simulation Of Hypersonic Aerothermoelasticity Using A Hybridized Discontinuous Galerkin Method, William Paul England

Theses and Dissertations

This work presents implementation of a hybridized discontinuous Galerkin (DG) method for robust simulation of the hypersonic aerothermoelastic multiphysics system. Simulation of hypersonic vehicles requires accurate resolution of complex multiphysics interactions including the effects of high-speed turbulent flow, extreme heating, and vehicle deformation due to considerable pressure loads and thermal stresses. However, the state-of-the-art procedures for hypersonic aerothermoelasticity are comprised of low-fidelity approaches and partitioned coupling schemes. These approaches preclude robust design and analysis of hypersonic vehicles for a number of reasons. First, low-fidelity approaches limit their application to simple geometries and lack the ability to capture small scale flow …

Sexual Dimorphism Of Glomerular Capillary Morphology In Rats, Zackarias Coker

Undergraduate Honors Theses

Chronic kidney disease (CKD) progresses faster in males than females; however, the underlying mechanisms remain poorly understood. Sex differences in glomerular capillary morphology has been hypothesized to contribute, in part, to the increased susceptibility to hypertension-induced renal injury and CKD progression in males, but this has not been investigated. The goal of the present study was to assess glomerular capillary morphology in male vs. female rats with intact kidneys and after uninephrectomy (UNX). We hypothesized that glomerular capillary radii (R_CAP) and length (L_CAP) would be greater in male rats.

Male (n=4) and female (n=4) with intact …

Asymptotic Properties And Separation Rates For Navier-Stokes Flows, Patrick Michael Phelps

Graduate Theses and Dissertations

In this dissertation, we investigate asymptotic properties of local energy solutions to the Navier-Stokes equations and develop an application which controls the separation of non-unique solutions in this class. Specifically, we quantify the rate at which two, possibly unique solutions evolving from the same data may separate pointwise away from a singularity. This is motivated by recent results on non-uniqueness for forced and unforced Navier-Stokes and analytical and numerical evidence suggesting non-uniqueness in the Leray class. Our investigation begins with discretely self-similar solutions known to exist globally in time and to be regular outside a space-time paraboloid. We prove decay …

The Characterization Of Atmospheric Turbulence And Its Effect On Laser Beam Propagation, Michael Cox

All Theses

Having a controlled environment to measure atmospheric turbulence is essential to understanding its effects on different laser beam characteristics. The Clemson Variable Turbulence Generator (VTG) has the capability to propagate a laser beam up to 100 m and be able to dial many turbulence settings up to a heat flux of 357 W/m². A high-speed camera, power detector, and high-resolution temperature probes characterize the VTG with theoretical turbulence spectrums. The exponent associated with the Rayleigh-Bénard (RB) temperature structure constant equation is studied. Two different laser beam profiles are used throughout this work: Gaussian and Asymmetric Perfect Vortex (APV). …

Studies Of The Ionosphere-Thermosphere Responses To Multi-Scale Energy Deposition Processes, Haonan Wu

All Dissertations

The Ionosphere-Thermosphere (I-T) system is greatly affected by the magnetospheric energy deposition from above and subjected to forcing from the lower atmosphere simultaneously. A central problem in studying the coupled I-T system is to analyze the multi-scale processes naturally embedded in both ways. Magnetospheric energy input such as auroral precipitation and electric field demonstrates multi-scale structures during magnetic storms, resulting in multi-scale I-T responses when deposited into the I-T system. To better quantify the multi-scale aurora and electric field, we developed a new data assimilation model based on a multi-resolution Gaussian process model to synthesize empirical models and observational data …

Mathematical Modeling Of Egain Droplets Sliding Down An Inclined Plane, Shawn Koohy, Kathryn Massey, Luis Schneegans, Megan Vezzetti, Keith Hillaire, Souradip Chattopadhyay, Jessie Chen, Carmen Lee, Karen Daniels

Undergraduate Research Symposium

Eutectic Gallium-Indium (EGaIn) is a room-temperature liquid metal alloy that dramatically changes its surface tension and dynamics under an applied electric field. EGaIn has been used heavily in soft electronics engineering due to its high conductivity, malleability, and safety. However, the absence of mathematical modeling in the current literature makes its behavior difficult to understand and predict. In this study, we present a one-dimensional lubrication model for the dynamics of an EGaIn droplet moving along an inclined plane. Our model incorporates essential physical effects and parameters including oxidation, capillary action, diffusion, gravity, and Marangoni effects. In particular, we incorporate effects …

Practical Implementation Of The Immersed Interface Method With Triangular Meshes For 3d Rigid Solids In A Fluid Flow, Norah Hakami

Mathematics Theses and Dissertations

When employing the immersed interface method (IIM) to simulate a fluid flow around a moving rigid object, the immersed object can be replaced by a virtual fluid enclosed by singular forces on the interface between the real and virtual fluids. These forces represent the impact of the rigid motion on the fluid flow and cause jump discontinuities across the interface in the whole flow field. Then, the IIM resolves the fluid flow on a fixed computational domain by directly incorporating the jump conditions across the interface into numerical schemes. Previous development of the method is limited to simple smooth boundaries. …

Numerical Study Of Owls’ Leading-Edge Serrations, Asif Shahriar Nafi

Electronic Theses and Dissertations

The silent flight ability of owls is often attributed to their unique wing morphology and its interaction with their wingbeat kinematics. Among these distinctive morphological features, leading-edge serrations stand out – these are rigid, miniature, hook-like patterns located at the leading edge of the primary feathers of their wings. It had been hypothesized that these leading-edge serrations serve as a passive flow control mechanism, influencing the aerodynamic performance and potentially affecting the boundary layer development over the wing, subsequently influencing wake flow dynamics. Despite being the subject of research spanning multiple decades, a consensus regarding the aerodynamic mechanisms underpinning owls’ …

Using Computational Fluid Dynamics And Optical Sensor Technology To Scale Cell Culture Platforms, Mandar Makwana

KGI Theses and Dissertations

Different cell culture vessels ranging from micro scale to laboratory scale to commercial scale play critical role in upstream process development for biologics manufacturing. Based on the mode of operation, cell culture vessels have different hydrodynamic environments, making it challenging to scale. Integrated approaches using computational tools supported by experimental studies can overcome these challenges. Computational Fluid Dynamics (CFD) is one such tool that can simulate hydrodynamics within the cell culture vessels and can provide insights at macro and micro-scale. Accuracy of a CFD model significantly depends on the fluid model and assumptions. Traditionally, simple two-equation fluid models were developed …

Passive Chlorination: Providing Clean Drinking Water To Rural Ecuadorian Communities, C.D. Tatko, Kyle Borror

Summer Research

In 2002, the World Health Organization (WHO) reported that nearly 1.7 million deaths worldwide were caused by unclean water. The risk of death is elevated for young children, for which the second cause of death worldwide is diarrheal disease, which is largely caused by microbes; these microbes, when unaddressed, can proliferate in drinking water. Health risks are further elevated in rural communities, which often lack access to the technology necessary to treat water for microbial contamination. This can be seen in Ecuador, in which only 52.8% of rural households have access to safe drinking water.

Modeling Self-Diffusiophoretic Janus Particles In Fluid, Kausik Das

HMC Senior Theses

We explore spherical Janus particles in which a chemical reaction occurs on one face, depleting a substrate in the suspending fluid, while no reaction occurs on the other face. The steady state concentration field is governed by Laplace’s equation with mixed boundary conditions. We use the collocation method to obtain numerical solutions to the equation in spherical coordinates. The asymmetry of the reaction gives rise to a slip velocity that causes the particle to move spontaneously in the fluid through a process known as self-diffusiophoresis. Using the Lorentz reciprocal theorem, we obtain the swimming velocity of the particle. We extend …

Long-Range And Chaotic Active Mixing Of Swimming Microbes In A Vortex Chain Flow, Nghia Le

Honors Theses

We present experiments studying the motion and active mixing of swimming mi- crobes in laminar, vortex-dominated fluid flows. We are testing a theory that predicts the existence of swimming invariant manifolds (SwIMs) - invisible, one-way barriers blocking the paths of self-propelled tracers in the flow in one direction. We also pro- pose that the SwIMs together can form chute structures in three-dimensional phase space that facilitate cross-vortex transport of the microbes. We also observe evidence of how these structures promote long-range transport at different non-dimensional velocities (microbe’s velocity relative to flow velocity). Long-range transport is quan- tified by measuring the …

Hamiltonian Structure Of 2d Fluid Dynamics With Broken Parity, Gustavo Machado Monteiro, Alexander G. Abanov, Sriram Ganeshan

Publications and Research

Isotropic fluids in two spatial dimensions can break parity symmetry and sustain transverse stresses which do not lead to dissipation. Corresponding transport coefficients include odd viscosity, odd torque, and odd pressure. We consider an isotropic Galilean invariant fluid dynamics in the adiabatic regime with momentum and particle density conservation. We find conditions on transport coefficients that correspond to dissipationless and separately to Hamiltonian fluid dynamics. The restriction on the transport coefficients will help identify what kind of hydrodynamics can be obtained by coarse-graining a microscopic Hamiltonian system. Interestingly, not all parity-breaking transport coefficients lead to energy conservation and, generally, the …