Physics Commons^™

Grinding Cocoa Changes Chocolate Properties, Joseph Cooney

Research on Capitol Hill

This research studies how the viscoelastic properties of chocolate change through the 72-hour grinding process of chocolate manufacturing. Utah State University's Aggie Chocolate Factory produces chocolate from single-origin sources, each of which has a unique flavor, and thus a unique chemistry. This research explores the effects of grinding time on the viscoelasticity of each of these origins' chocolate types, including dark, sweet dark chocolate, and milk chocolate. Chocolate is a non-Newtonian fluid and therefore the Casson model (eq. 1) was used to obtain values for viscosity and yield stress, τ^(1/2)=τ_0^(1/2)+(η_PL y' )^(1/2) (1) Where τ is the shear stress measured …

Rheological Characterization Of Blood-Mimicking Fluids For Use In Particle Image Velocimetry, Anorin S. Ali

Undergraduate Student Research Internships Conference

Blood-mimicking fluids (BMFs) are often used to investigate blood flow using physical replicas of vessels with cardiovascular disease. Particle image velocimetry (PIV) is used with silicone poly-dimethyl siloxane (PDMS) vascular models to visualize this flow. The challenge is creating a blood-mimicking fluid that matches the viscosity profile, viscoelasticity, and density of whole blood while also matching the refractive index (RI) of PDMS. Water-glycerol solutions are commonly used with sodium iodide (NaI) added to increase the RI without changing viscosity. However, NaI is expensive, stains easily, and turns fluids from optically clear to yellow in less than a day. Furthermore, without …

Nanoscale Hybrid Electrolytes With Viscosity Controlled Using Ionic Stimulus For Electrochemical Energy Conversion And Storage, Sara T. Hamilton, Tony G. Feric, Sahana Bhattacharyya, Nelly M. Cantillo, Steven G. Greenbaum, Thomas A. Zawodzinski, Ah-Hyung Alissa Park

Publications and Research

As renewable energy is rapidly integrated into the grid, the challenge has become storing intermittent renewable electricity. Technologies including flow batteries and CO 2 conversion to dense energy carriers are promising storage options for renewable electricity. To achieve this technological advancement, the development of next generation electrolyte materials that can increase the energy density of flow batteries and combine CO 2 capture and conversion is desired. Liquid-like nanoparticle organic hybrid materials (NOHMs) composed of an inorganic core with a tethered polymeric canopy (e.g., polyetheramine (HPE)) have a capability to bind chemical species of interest including CO 2 and redox-active species. …

Editorial For The Special Issue On Micromachines For Non-Newtonian Microfluidics, Lanju Mei, Shizhi Qian

Mechanical & Aerospace Engineering Faculty Publications

In lieu of an abstract, this is an excerpt from the first page.

Microfluidics has seen a remarkable growth over the past few decades, with its extensive applications in engineering, medicine, biology, chemistry, etc [...]

Droplet-Based Fuel Property Measurements, Wanjun Dang

LSU Doctoral Dissertations

Ongoing work to find renewable biofuels to function as drop-in replacements or blending components with gasoline has identified a large number of fuel candidates. Given the vast number of potential biomass-derived fuel molecules and limited sample sizes, screening tools are required to down-select candidate fuels having desired physical properties to ensure good engine performance. This work investigates approaches for rapid screening of candidate fuels using micro-liter sample sizes targeting four properties -- surface tension, viscosity, heat of vaporization (HOV), and vapor pressure. Measurement techniques for fuel properties are developed based on unit phenomena for liquid fuel droplets including droplet oscillation …

Benchmarking Nimrod Continuum Kinetic Formulations Through The Steady-State Poloidal Flow, Joseph R. Jepson, Chris C. Hegna, Eric D. Held, J. Andrew Spencer, B. C. Lyons

All Physics Faculty Publications

In this work, continuum kinetic formulations are employed as a mechanism to include closure physics in an extended magnetohydrodynamics model. Two continuum kinetic approaches have been implemented in the plasma fluid code NIMROD [Sovinec et al., “Nonlinear magnetohydrodynamics with high-order finite elements,” J. Comput. Phys. 195, 355 (2004)] including a Chapman–Enskog-like (CEL) formulation and a more conventional δf approach. Ion kinetic closure schemes are employed to describe the neoclassical flow properties in axisymmetric toroidal geometry. In particular, predictions for steady-state values of poloidal flow profiles in tokamak geometry are provided using both the δf formulation and two different solution …

Stability Analysis Of Circular Robe’S R3bp With Finite Straight Segment And Viscosity, Bhavneet Kaur, Sumit Kumar, Shipra Chauhan, Dinesh Kumar

Applications and Applied Mathematics: An International Journal (AAM)

In this paper, the effect of viscous force on the linear stability of equilibrium points of the circular Robe’s restricted three-body problem (CRR3BP) with smaller primary as a finite straight segment is studied. The present model comprises of a bigger primary m^*₁ which is a rigid spherical shell filled with a homogeneous incompressible fluid of density ρ₁ and the smaller primary m₂ lies outside the shell. The infinitesimal mass m₃ is a small solid sphere of density ρ₃ moving inside m^*₁. The pertinent equations of motion of m₃ are derived …

Protein Conformational Entropy Is Not Slaved To Water, Bryan S Marques, Matthew A Stetz, Christine Jorge, Kathleen G Valentine, A Joshua Wand, Nathaniel V Nucci

Faculty Scholarship for the College of Science & Mathematics

Conformational entropy can be an important element of the thermodynamics of protein functions such as the binding of ligands. The observed role for conformational entropy in modulating molecular recognition by proteins is in opposition to an often-invoked theory for the interaction of protein molecules with solvent water. The "solvent slaving" model predicts that protein motion is strongly coupled to various aspects of water such as bulk solvent viscosity and local hydration shell dynamics. Changes in conformational entropy are manifested in alterations of fast internal side chain motion that is detectable by NMR relaxation. We show here that the fast-internal side …

Constraining The Initial Conditions And Temperature Dependent Viscosity With Three-Particle Correlations In Au+Au Collisions, L. Adamczyk, James K. Adkins, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, N. N. Ajitanand, I. Alekseev, D. M. Anderson, R. Aoyama, A. Aparin, D. Arkhipkin, E. C. Aschenauer, M. U. Ashraf, A. Attri, G. S. Averichev, X. Bai, V. Bairathi, A. Behera, R. Bellwied, A. Bhasin, A. K. Bhati, P. Bhattarai, J. Bielcik, J. Bielcikova, L. C. Bland, I. G. Bordyuzhin, J. Bouchet, J. D. Brandenburg, A. V. Brandin, D. Brown, Renee H. Fatemi, Suvarna Ramachandran

Physics and Astronomy Faculty Publications

We present three-particle mixed-harmonic correlations ⟨cos(mф_α + nф_b – (m + n)ф_c)⟩ for harmonics m, n = 1 – 3 for charged particles in √s_NN = 200 GeV Au+Au collisions at RHIC. These measurements provide information on the three-dimensional structure of the initial collision zone and are important for constraining models of a subsequent low-viscosity quark–gluon plasma expansion phase. We investigate correlations between the first, second and third harmonics predicted as a consequence of fluctuations in the initial state. The dependence of the correlations on the pseudorapidity separation …

Viscosities, Diffusion Coefficients, And Mixing Times Of Intrinsic Fluorescent Organic Molecules In Brown Limonene Secondary Organic Aerosol And Tests Of The Stokes–Einstein Equation, Dagny A. Ullmann, Mallory L. Hinks, Adrian M. Maclean, Christopher Butenhoff, James W. Grayson, Kelley Barsanti, Jose L. Jimenez, Sergey A. Nizkorodov, Saeid Kamal, Allan K. Bertram

Physics Faculty Publications and Presentations

Viscosities and diffusion rates of organics within secondary organic aerosol (SOA) remain uncertain. Using the bead-mobility technique, we measured viscosities as a function of water activity (a_w) of SOA generated by the ozonolysis of limonene followed by browning by exposure to NH₃ (referred to as brown limonene SOA or brown LSOA). These measurements together with viscosity measurements reported in the literature show that the viscosity of brown LSOA increases by 3–5 orders of magnitude as the aw decreases from 0.9 to approximately 0.05. In addition, we measured diffusion coefficients of intrinsic fluorescent organic molecules within brown …

Linking Structure And Dynamics In Metallic Liquids: A Combined Experimental And Molecular Dynamics Approach, Robert Ashcraft

Arts & Sciences Electronic Theses and Dissertations

A major outstanding problem in condensed matter physics is the nature of the glass transition, in which a rapidly cooled liquid can bypass the transition into a crystalline state and the liquid structure is "frozen-in" due to kinetic arrest. To characterize the fundamental features behind this transition the liquid, both in the high temperature (equilibrium) and supercooled state, needs to be better understood. By examining the relationship between structure and dynamics a better characterization of the liquid state and a determination of the mechanisms that are ultimately important for the formation of the glass can be gained. In this dissertation, …

Drainage, Rebound And Oscillation Of A Meniscus In A Tube, Jeremy Marston, Garrett Toyofuku, Chao Li, Tadd T. Truscott, Jamal Uddin

Mechanical and Aerospace Engineering Faculty Publications

In this paper, the drainage and subsequent rebound of a liquid column in a cylindrical tube is examined experimentally and theoretically. When liquid is drawn up into a capillary and then released under gravity, inertia allows the meniscus to overshoot the equilibrium capillary rise height. The meniscus then rebounds up the tube, again overshooting the equilibrium height and undergoes oscillation. By varying both the immersion depth and radius of the tube, one can observe rich dynamical behavior, with the most dramatic being the formation of a fast liquid jet, barely visible to the naked eye but easily captured with high-speed …

Efficient General Computational Method For Estimation Of Standard Atmosphere Parameters, Nihad E. Daidzic Ph.D., Sc.D.

International Journal of Aviation, Aeronautics, and Aerospace

Knowledge of standard air temperature, pressure, density, speed of sound, and viscosity as a function of altitude is essential information in aircraft design, performance testing, pressure altimeter calibration, and several other aeronautical engineering and aviation science applications. A new efficient computational method for rapid calculations of standard atmospheric parameters up to 86 orthometric km is presented. Additionally, mass and weight of each standard atmospheric layer were calculated using a numerical integration method. The sum of all fractional masses and weights represents the total mass and weight of Earth’s atmosphere. The results obtained here agree well with measurements and models of …

Mitigation Of Moving Shocks In An Expanding Duct, Veraun Chipman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Inviscid flow theory governs the bulk motion of a gas at some distance away from the walls (i.e. outside the boundary layer). That is to say, there are no viscous forces in the bulk flow, which is modeled using the Euler equations. The Euler equations are simply the Navier-Stokes equations with zero viscosity terms. An ideal inviscid fluid, when brought into contact with a surface or wall, would naturally slip right past it since the fluid has no viscosity. In real life, however, a thin boundary layer forms between the wall or surface and the bulk flow. Shock wave boundary …

Direct Observation Of Self-Assembled Chain-Like Water Structures In A Nanoscopic Water Meniscus, Byung I. Kim, Ryan D. Boehm, Jeremy R. Bonander

Physics Faculty Publications and Presentations

Sawtooth-like oscillatory forces generated by water molecules confined between two oxidized silicon surfaces were observed using a cantilever-based optical interfacial force microscope when the two surfaces approached each other in ambient environments. The humidity-dependent oscillatory amplitude and periodicity were 3-12 nN and 3-4 water diameters, respectively. Half of each period was matched with a freely jointed chain model, possibly suggesting that the confined water behaved like a bundle of water chains. The analysis also indicated that water molecules self-assembled to form chain-like structures in a nanoscopic meniscus between two hydrophilic surfaces in air. From the friction force data measured simultaneously, …

Investigating The Benefit Of Using Magnetorheological Fluids In A Shock Absorber, Chao Guo

Senior Theses

The beneficial properties of magnetorheological fluids are applied in the design and testing of a prototype suspension system. Because viscosity of these fluids increased tremendously under the influence of a magnetic field, a suspension shock absorber containing magnetorheological fluids fluid is proposed. The shock system tested displayed resistance to motion with respect to the magnetic field strength.

Thermophysical And Structural Measurements Of Liquid Metallic Alloys Using Electrostatic Levitation, James Christopher Bendert

All Theses and Dissertations (ETDs)

In the study of the glass transition, the properties of high temperature liquids in their equilibrium and supercooled states may provide clues to the question of why certain compositions form glasses more easily than others. In metallic alloys such measurements are difficult due to the high reactivity and high melting temperatures of these liquids. Levitation methods provide a solution this problem by isolating liquid alloys from their environments. Here, the techniques of data acquisition and analysis for thermophysical property measurements under electrostatic levitation are presented, with demonstrative examples from select compositions from the Cu-Zr system. The development of techniques and …

Viscosity Measurements On Colloidal Dispersions (Nanofluids) For Heat Transfer Applications, Jessica Townsend, Rebecca J. Christianson, D Venerus, J Buongiorno, M A. Kedzierski, Et Al.

Rebecca J. Christianson

This article reports viscosity data on a series of colloidal dispersions collected as part of the International Nanofluid Property Benchmark Exercise (INPBE). Data are reported for seven different fluids that include dispersions of metal-oxide nanoparticles in water, and in synthetic oil. These fluids, which are also referred to as nanofluids, are currently being researched for their potential to function as heat transfer fluids. In a recently published paper from the INPBE study, thermal conductivity data from more than 30 laboratories around the world were reported and analyzed. Here, we examine the influence of particle shape and concentration on the viscosity …

Viscosity Measurements On Colloidal Dispersions (Nanofluids) For Heat Transfer Applications, Jessica Townsend, Rebecca J. Christianson, D Venerus, J Buongiorno, M A. Kedzierski, Et Al.

Jessica Townsend

This article reports viscosity data on a series of colloidal dispersions collected as part of the International Nanofluid Property Benchmark Exercise (INPBE). Data are reported for seven different fluids that include dispersions of metal-oxide nanoparticles in water, and in synthetic oil. These fluids, which are also referred to as nanofluids, are currently being researched for their potential to function as heat transfer fluids. In a recently published paper from the INPBE study, thermal conductivity data from more than 30 laboratories around the world were reported and analyzed. Here, we examine the influence of particle shape and concentration on the viscosity …

The Inexorable Resistance Of Inertia Determines The Initial Regime Of Drop Coalescence, Joseph Paulsen, Justin C. Burton, Sidney R. Nagel, Santosh Appathurai, Michael T. Harris, Osman A. Basaran

Physics - All Scholarship

Drop coalescence is central to diverse processes involving dispersions of drops in industrial, engineering, and scientific realms. During coalescence, two drops first touch and then merge as the liquid neck connecting them grows from initially microscopic scales to a size comparable to the drop diameters. The curvature of the interface is infinite at the point where the drops first make contact, and the flows that ensue as the two drops coalesce are intimately coupled to this singularity in the dynamics. Conventionally, this process has been thought to have just two dynamical regimes: a viscous and an inertial regime with a …

What Brown Saw And You Can Too, Philip Pearle, Brian Collett, Kenneth Bart, David Bilderback, Dara Newman, D. Scott Samuels

Biological Sciences Faculty Publications

A discussion of Robert Brown’s original observations of particles ejected by pollen of the plant Clarkia pulchella undergoing what is now called Brownian motion is given. We consider the nature of those particles and how he misinterpreted the Airy disk of the smallest particles to be universal organic building blocks. Relevant qualitative and quantitative investigations with a modern microscope and with a “homemade” single lens microscope similar to Brown’s are presented.

Volume Viscosity In Fluids With Multiple Dissipative Processes, Allan J. Zuckerwar, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

The variational principle of Hamilton is applied to derive the volume viscosity coefficients of a reacting fluid with multiple dissipative processes. The procedure, as in the case of a single dissipative process, yields two dissipative terms in the Navier-Stokes equation: The first is the traditional volume viscosity term, proportional to the dilatational component of the velocity; the second term is proportional to the material time derivative of the pressure gradient. Each dissipative process is assumed to be independent of the others. In a fluid comprising a single constituent with multiple relaxation processes, the relaxation times of the multiple processes are …

Response To "Comment On Variational Approach To The Volume Viscosity Of Fluids" [Phys. Fluids 18, 109101 (2006)], Allen J. Zuckerwar, Robert L. Ash

Mechanical & Aerospace Engineering Faculty Publications

We respond to the Comment of Markus Scholle and therewith revise our material entropy constraint to account for the production of entropy. (c) 2006 American Institute of Physics.

Excess Properties Of Alcohol - Water Systems At 298.15 K, Hülya Yilmaz

Turkish Journal of Physics

Dielectric constants \varepsilon, viscosities \eta, refractive indices n and densities d have been measured over the entire mole fraction range for the water - methyl, ethyl, n-propyl alcohol binary systems at 298.15 K. From the experimental data excess dielectric constants \varepsilon^E, excess viscosities \eta^E and Kirkwood correlation factors g_k have been calculated and studied. Their behaviour suggests the existence of intermolecular interactions and plotted curves show that excess dielectric constant and g_k values decrease with the increasing of carbon atom number, while excess viscosity increases.

Strong Dissipative Behavior In Quantum Field Theory, Arjun Berera, Marcelo Gleiser, Rudnei O. Ramos

Dartmouth Scholarship

We study the conditions under which an overdamped regime can be attained in the dynamic evolution of a quantum field configuration. Using a real-time formulation of finite temperature field theory, we compute the effective evolution equation of a scalar field configuration, quadratically interacting with a given set of other scalar fields. We then show that, in the overdamped regime, the dissipative kernel in the field equation of motion is closely related to the shear viscosity coefficient, as computed in scalar field theory at finite temperature. The effective dynamics is equivalent to a time-dependent Ginzburg-Landau description of the approach to equilibrium …

Fiber-Optics Surface-Light-Scattering Spectrometer, Padetha Tin, J. Adin Mann, William V. Meyer, Thomas W. Taylor

Physics Faculty Publications

We have developed a fiber-optics surface-light-scattering spectrometer completely designed with optical fiber components. To the best of our knowledge, this is the first demonstration of a noninvasive measurement of the surface tension and the viscosity of simple liquid-vapor interfaces with a fiber-optics-based sensor system. With this approach we obtain a compact size, a significant increase in the signal-to-noise ratio, and the ability to select from a continuum of wave vectors. (C) 1997 Optical Society of America.

The Role Of Diffusion In The Binding Of Carbon Monoxide To Protoheme In High-Viscosity Solvents, David Peak

All Physics Faculty Publications

Studies of the flash photolysis of heme‐bearing proteins have often assessed the role of ligand diffusion in very approximate ways and a disagreement about the importance of ligand diffusion exists in the literature as a result. This paper provides a somewhat more sytematic analysis of diffusional effects than has been given previously for the simple case of ligand–protoheme binding. The model developed here is fit to the available data for the ligand CO in glycerol–water solvents. The fit suggests that diffusional motions become important for the kinetics of this system for temperatures below 270 K and that these motions are …

Studies Of The Reorientational Relaxation Of Pyridine In Water By Depolarized Rayleigh Light Scattering, C. H. Wang, Scott L. Whittenburg, P. A. Lund, D. H. Christensen

Chemistry and Biochemistry Faculty Publications

The depolarized Rayleigh spectra of aqueous solutions of pyridine have been studied using a high‐finesse Fabry–Perot interferometer as a function of temperature and concentration. The Rayleigh relaxation times are found to have a complex concentration and viscosity dependence. The classical Stokes–Einstein–Debye equation for molecular reorientation breaks down in this system. The Rayleigh relaxation time of pyridine molecules is not determined by the macroscopic shear viscosity of the solution. The specific interaction due to the formation of hydrogen bonds between pyridine and water molecules plays a very important role in affecting the relaxation time. At a fixed temperature the plot of …

Light Scattering Studies Of Transverse Sound Wave And Molecular Motion In Benzonitrile, Scott L. Whittenburg, C. H. Wang

Chemistry and Biochemistry Faculty Publications

The zero‐frequency shear wave dip appearing in the depolarized Rayleigh spectrum in benzonitrile has been studied as a function of concentration and temperature. The solution study was carried out at constant viscosity equal to the viscosity of liquid benzonitrile at each temperature. The result indicates that the presence of shear wave fine structure does not depend on the collective orientational fluctuations. The orientational and vibrational relaxation times of benzonitrile were measured at various concentrations and temperatures. The orientational relaxation times show no concentration dependence at any temperature, suggesting that the pair correlation is negligible at all concentrations. The orientational relaxation …

Light Scattering Studies Of Rotational And Vibrational Relaxations Of Acetonitrile In Carbon Tetrachloride, Scott L. Whittenburg, C. H. Wang

Chemistry and Biochemistry Faculty Publications

The rotational and vibrational relaxation times of acetonitrile–carbon tetrachloride solutions were investigated as a function of concentration, viscosity, and temperature using depolarized Rayleigh and Raman scattering. Using a Fabry‐Perot interferometer and single frequency laser source, we have shown that reliable results for the single particle orientational correlation times (τ_s) for CH₃CN can be obtained by carrying out a concentration dependent depolarized Rayleigh scattering study. Raman scattering was shown to yield inconsistent results for τ_s in CH₃CN. At constant viscosity, it was found that the Rayleigh scatteringrelaxation time (τ_Ray) of CH_{3 …}