Russell Keanini

Russell Keanini
University of North Carolina at Charlotte | UNC Charlotte · Department of Mechanical Engineering and Engineering Science

Ph.D. Berkeley

About

80
Publications
14,688
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Introduction
Our research groups are working on three problems: 1) We're attempting to work out statistical mechanics models of the equilibrium and nonequilibrium dynamics of single, liquid-state molecules. 2) We're continuing to develop connections between the dynamics of vibration-driven grain systems and dense molecular hydrodynamic systems, with the goal of showing that the former can be used as predictive, macroscopic analogs for studying the latter. 3) Along with Professor Missy Eppes, we're studying the physical, geological, and environmental features that drive small- and large-scale fracture in rock.
Additional affiliations
July 1992 - present
University of North Carolina at Charlotte
Position
  • Professor (Full)

Publications

Publications (80)
Preprint
Full-text available
A stochastic method is described for estimating Green's functions (GF's), appropriate to linear advection-diffusion-reaction transport problems, evolving in arbitrary geometries. By allowing straightforward construction of approximate, though high-accuracy GF's, within any geometry, the technique solves the central challenge in obtaining Green's fu...
Technical Report
Full-text available
To fully understand how liquids flow, it is crucial for researchers to build models which can accurately recreate their behaviours on molecular scales – yet since the time of Newton, the complexities involved have presented numerous challenges. In their research, Prof Russ Keanini, Prof Peter Tkacik and Prof Jerry Dahlberg at the University of Nort...
Article
Full-text available
Physical arguments and comparisons with published experimental data suggest that in simple liquids: (i) single-molecule-scale viscous forces are produced by temperature-dependent London dispersion forces, (ii) viscosity decay with increasing temperature reflects electron cloud compression and attendant suppression of electron screening, produced by...
Article
Full-text available
Physical arguments and comparisons with published experimental data suggest that in simple liquids: (i) single-molecule-scale viscous forces are produced by temperature-dependent London dispersion forces, (ii) viscosity decay with increasing temperature reflects electron cloud compression and attendant suppression of electron screening, produced by...
Article
Full-text available
In this Supplement, we employ the same arguments used in [3] to develop Navier-stokes equations describing the flow of vibration-driven grain beds. It is important to recognize that, in contrast to the particle based Langevin models proposed in the article, the Single Molecule Scale (SMS) Navier-Stokes equations developed here provide a field-based...
Preprint
Full-text available
Physical arguments and comparisons with published experimental data suggest that in simple liquids: i) single-molecule-scale viscous forces are produced by temperature-dependent London dispersion forces, ii) viscosity decay with increasing temperature reflects electron cloud compression and attendant suppression of electron screening, produced by i...
Article
Full-text available
Confined, vibration-driven grain piles exhibit fluid-like properties, in particular, predictable, non-random flow patterns, hydrodynamic modal response to vibrational forcing, and a persistent, spatially uniform tendency toward local statistical mechanical equilibrium. This paper presents a technique that combines particle image velocimetry of vibrati...
Article
Full-text available
An analog, macroscopic method for studying molecular-scale hydrodynamic processes in dense gasses and liquids is described. The technique applies a standard fluid dynamic diagnostic, particle image velocimetry (PIV), to measure: i) velocities of individual particles (grains), extant on short, grain-collision time-scales, ii) velocities of systems o...
Conference Paper
Methods for reducing surface reflections during PIV measurements are commonly discussed, but the effects of those surface reflections on PIV measurements are generally neglected. In this study, a comparison of light gathering characteristics of an experimental tomographic PIV system is made using a bluff body model that is coated: i) first, with a...
Article
Full-text available
A recent article in Reviews of Geophysics combined mathematical modeling, fracture mechanics theory and engineering research data to provide new insights into a critical geological process.
Article
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This work constructs a fracture mechanics framework for conceptualizing mechanical rock breakdown and consequent regolith production and erosion on the surface of Earth and other terrestrial bodies. Here our analysis of fracture mechanics literature explicitly establishes for the first time that all mechanical weathering in most rock types likely p...
Article
Full-text available
Vibratory finishing processes are finding increased application in the finishing of high value metallic components. Despite the growth of these processes, few models exist to predict workpiece material removal variations and surface finish uniformity. This paper explores the potential of modelling the media as a continuum and utilizing commercial c...
Article
Full-text available
Experimental evidence and theoretical modeling suggest that piles of confined, high-restitution grains, subject to low-amplitude vibration, can serve as experimentally-accessible analogs for studying a range of liquid-state molecular hydrodynamic processes. Experiments expose single-grain and multiple-grain, collective dynamic features that mimic t...
Presentation
Full-text available
The formation and diminution of rock debris, sediment and soil at and near Earth’s surface is driven in large part by in situ, non-transport related, rock cracking. Given the relatively low magnitude stresses that arise in surface and near-surface settings, this production and diminution of granular material is likely strongly influenced and/or dri...
Article
Although precision polishing of optical grade components using pitch based tools is still common practice, the process has not received the same level of scientific attention as other precision material removal processes. Building on previous research results, this paper demonstrates the relationship between low amplitude, broad spectrum vibrationa...
Conference Paper
Full-text available
Vibrational finishing processes are utilized for deburring and generating uniform finishes on metallic and plastic components for wide range of applications which include aerospace, energy, and bio-medical. The nature of the generated surfaces will depend on the both the composition and geometry of the media, and how the media interacts with the wo...
Article
Full-text available
The classical picture of shock evolution in nozzles holds that under over-expanded flow conditions, a single, nominally normal shock exists within the nozzle. Focusing on the highly dynamic flow produced during blow-down of an experimental, high-nozzle pressure ratio, planar nozzle, this article presents visual evidence that shock-trains - here, a...
Conference Paper
Full-text available
We present experimental results that demonstrate the ability of mid-IR imaging to map blood vessels 0.75cm deep in muscle tissue. Selective heating of the blood with LED sources provides the contrast in these mid-IR images.
Article
Full-text available
Experimental testing, using both commercially available polishing machines and a specially built test platform, demonstrates that material removal rates (MRRs) observed during polishing of fused silica are strongly affected by nanometer-scale vibration amplitudes. Specifically, a nanometer level increase in system vibrations can produce MRRs approx...
Article
Full-text available
A series of fi full-scale, nearly conventional, curtain wall specimens was tested in the UNC Charlotte Structures Laboratory. Specimens were subjected to quasi-static, uniform, out-of-plane loading to failure under displacement control. The tests were performed to obtain complete resistance curves, including the nonlinear behavior of the specimens...
Article
Full-text available
High-fidelity numerical experiments and theoretical modelling are used to study the dynamics of a sounding-rocket-scale rocket subject to altitude-dependent random wind and nozzle side loads and deterministic aerodynamic loading. This paper complete a series of studies that showed that Ornstein–Uhlenbeck (OU) rotational dynamics arise when random n...
Article
A long-standing, though ill-understood problem in rocket dynamics, rocket response to random, altitude-dependent nozzle side-loads, is investigated. Side loads arise during low altitude flight due to random, asymmetric, shock-induced separation of in-nozzle boundary layers. In this paper, stochastic evolution of the in-nozzle boundary layer separat...
Article
Full-text available
Research Highlights: > Systematic approach for physically probing nonlinear and random evolution problems. > Evolution of vortex sheets corresponds to evolution of an Ornstein-Uhlenbeck process. > Organization of near-molecular scale vorticity mediated by hydrodynamic modes. > Framework allows calculation of vorticity evolution within random strain...
Article
Full-text available
Abstract Complex flow features within rocket nozzles can exert significant influence on both the dynamics and safety of rockets during flight. Specifically, under over-expanded flow conditions, during, low altitude flight, random, often large side loads can appear within nozzles. While significant research has focused on this classical problem, due...
Article
Full-text available
It is well known that the dynamic performance of a rocket or launch vehicle is enhanced when the length of the divergent section of its nozzle is reduced or the nozzle exit area ratio is increased. However, there exists a significant performance trade-off in such rocket nozzle designs due to the presence of random side loads under overexpanded nozz...
Article
Full-text available
A large class of physically important nonlinear and nonhomogeneous evolution problems, characterized by advection-like and diffusion-like processes, can be usefully studied by a time-differential form of Kolmogorov's solution of the backward-time Fokker-Planck equation. The differential solution embodies an integral representation theorem by which...
Article
Time average shock-induced boundary layer separation is investigated using scale analyses, analytical modeling, and experiments. While the study focuses on turbulent boundary layer separation in overexpanded rocket nozzles, many of the analyses presented apply to the broad family of free interaction, shock-separated flows in which the structure of...
Article
Full-text available
Three stochastic-based methods are proposed for solving unsteady scalar transport problems in bounded, single-phase domains. The first (Method I), a local solution appropriate to problems having Dirichlet conditions, adapts a well-known local stochastic solution of a backward Fokker–Planck equation to scalar transport. Method II, a local solution a...
Article
Full-text available
Scale analyses indicate that three distinct contaminant mass-transfer processes, occurring on distinct time scales, underlie formation of the alpha case on small titanium castings. High rates of mold-to-liquid metal mass transfer occur during an extremely short induction period, the length of which is determined by the time required for heterogeneo...
Article
Full-text available
The response of optical fiber ribbon entrance menisci to impulsive lateral motion of the ribbon or coating die is theoretically investigated. In the limit where the characteristic axial coating pressure increase along the meniscus is much larger than the characteristic gas viscous shear stress along the meniscus, the meniscus free surface is descri...
Article
Full-text available
A method for enhancing the stability of parabolic inverse heat conduction problems (IHCP) is presented. The investigation extends recent work on non-iterative finite element-based IHCP algorithms which, following Becks two-step approach, first derives a discretized standard form equation relating the instantaneous global temperature and surface hea...
Article
Full-text available
This article develops a theoretical model of the two-chamber pressure casting process. In this process, a molten metal drop, formed by arc melting a solid ingot, falls into a conical crucible attached to a gas-filled, porous cast mold. An energy-based formulation of the mold-filling process is developed which focuses on the drop’s motion within the...
Article
Full-text available
In [18], the authors developed a non-iteraitve finite element-based inverse method for estimating surface heat-flux histories on heat conducting parts. The method relies on the obervation that a sequential minimization of the least squares norm between measured and computed temperatures leads to a linear, implicitly regularized matrix normal equati...
Article
Full-text available
This article theoretically and experimentally characterizes direct contact, packed bed thermal gradient attenuators in which a fluid control stream, subject to broadband thermal disturbances, flows through a thermally attenuating packed bed medium. The theoretical model decomposes the device into three subsystems: an upper mixing volume, the packed...
Article
A non-iterative, ÿnite element-based inverse method for estimating surface heat ux histories on ther-mally conducting bodies is developed. The technique, which accommodates both linear and non-linear problems, and which sequentially minimizes the least squares error norm between corresponding sets of measured and computed temperatures, takes advant...
Article
Studies have been performed using high- and low-copper amalgams to measure the amounts of mercury dissolution from dental amalgam in liquids such as artificial saliva; however, in most cases, mercury dissolution has been measured under static conditions and as such, may be self-limiting. This study measured the mercury release from low- and high-co...
Article
Full-text available
During ground-tests of most production rocket engines over the last 30 years, large asymmetric transient side loads coming from the nozzle and related steady-state vibrational loads within the nozzle have been measured. The widely varying magnitude of these loads has been large enough to fail interfacing components as well as nozzles in these engin...
Article
Full-text available
A precision method for attenuating temperature variations in a high-throughput control fluid stream is described and analyzed. In contrast to earlier investigations, the present study emphasizes heat transfer analysis of the constituent control device and derives theoretical descriptions of system responses to time-varying fluid temperatures. Exper...
Article
Full-text available
This article reports an experimental and theoretical investigation of mercury dissolution from dental amalgams immersed in neutral (noncorrosive) and acidic (corrosive) flows. Atomic absorption spectrophotometric measurements of Hg loss indicate that in neutral flow, surface oxide films formed in air prior to immersion persist and effectively suppr...
Article
Full-text available
Second-order streaming in a thin fluid layer driven by one or two opposed, tangentially oscillating wavy walls is theoretically investigated. In contrast to the well-studied problem of oscillatory flow past a stationary boundary, the present problem is subject to a nonhomogeneous second-order boundary velocity condition. A combination of steady Rey...
Article
This paper introduces design and measurement principles underlying resonance-based pressure measurement and anemometry, emphasizing application to high temperature, optically opaque flows. Due to typically extreme conditions, associated high resolution anemometries have not been developed. The method described incorporates a novel dual-cantilever P...
Conference Paper
Particle transport associated with quasistatic second-order streaming flow in wavy-walled channels is theoretically investigated. Small amplitude tangential oscillations of both walls drive steady second-order streaming, while superposed, large-amplitude oscillations of one wall produce the time-dependent, quasisteady flows of interest. Short-time...
Conference Paper
This paper describes the first phase of a two-part project designed to develop a new anemometry method for use in high temperature liquid metal flows. The device will incorporate a dual-cantilever, PZT-driven touch sensor housed within a sealed, temperature resistant ceramic Pitot tube. Due to differing cantilever lengths, the device’s unloaded spe...
Article
This article develops an implicit inverse method for reconstructing dynamic multidimensional phase boundaries. The technique is suitable for problems having small liquid phase Peclet numbers, Per = (V̂rL̂/α̂), where V̂r is the characteristic liquid phase velocity scale evaluated relative to the solid phase velocity scale, L̂ is a characteristic len...
Article
Cryosurgical freezing of dense lung tumors within healthy lung tissue is investigated using numerical and order-of-magnitude analyses. The numerical model indicates that the freezing front accelerates as it leaves the tumor and enters the surrounding healthy, low density lung tissue, a prediction confirming the earlier analytical work of Bischof, B...
Article
This paper describes the first phase of a two-part project designed to develop a new anemometry method for use in high temperature liquid metal flows. The device will incorporate a dual-cantilever, PZT-driven touch sensor housed within a sealed, temperature resistant ceramic Pitot tube. Due to differing cantilever lengths, the device's unloaded spe...
Article
Particle transport associated with quasistatic second-order streaming flow in wavy-walled channels is theoretically investigated. Small amplitude tangential oscillations of both walls drive steady second-order streaming, while superposed, large-amplitude oscillations of one wall produce the time-dependent, quasisteady flows of interest. Short-time...
Article
Full-text available
An asymptotic model of work roll heat transfer is developed using a multiple time scale approach. The model is appropriate under typical high Peclet number rolling conditions and provides a unified framework for relating previous roll heat transfer models. The solution consists of a fast time scale thermal boundary layer near the roll surface, alon...
Article
An inverse method suitable for use with remote temperature measurements, is used to estimate time-dependent, axially-varying surface heat flux distributions during rolling. It is found that the diffusive time scale between the roll surface and the embedded measurement array determines the data sample rate and the solution's temporal resolution. The...
Article
An asymptotic model of work roll heat transfer is described. The model is appropriate under typical high Peclet number rolling conditions and provides a unified framework for relating previous roll heat transfer models. The solution consists of a fast time scale thermal boundary layer near the roll surface and a slow time scale core heat transfer p...
Article
This article develops an implicit inverse method for reconstructing dynamic multidimensional phase boundaries. The technique is suitable for problems having small liquid phase Peclet numbers; under these conditions, a multidimensional Stefan problem emerges. Explicit front-tracking procedures are eliminated by incorporating the latent heat effect i...
Article
Full-text available
The purpose of this research is to study flow and heat transfer within the cooling water pond at Catawba Nuclear Station during a hypothetical accident. The pond is used as the assured source of cooling for decay heat removal in the event that the primary cooling source is lost. The first objective in this study is to develop a two-dimensional fini...
Article
Full-text available
This paper describes an inverse technique for imaging multi-dimensional optically opaque phase change boundaries and associated near-melt solid phase temperature fields. The algorithm confines calculations to the solid region immediately surrounding the melt interface, uses a coarse, spatially limited finite element mesh, and is capable of determin...
Article
A method for measuring time-varying surface temperature distributions using high frame rate visible imaging CCD cameras is described. The technique is based on an ad hoc model relating measured radiance to local surface temperature. This approach is based on the fairly non-restrictive assumptions that atmospheric scattering and absorption, and seco...
Article
An inverse finite element method is developed for simultaneous solution of multi-dimensional solid-liquid phase boundaries and associated three-dimensional solid phase temperature fields. The technique, applicable to quasisteady phase change problems, fixes element nodes at known temperature locations and uses a coarse, spatially limited mesh. This...
Article
Full-text available
Electron collisionless (Knudsen) layers near evaporating plasma-heated anodes are analyzed, and a corresponding general model is formulated. Since the ratio of ion to electron mean free paths is small, the layer is subdivided into ion continuum and ion collisionless layers. Distribution functions for charged species are derived and auxiliary non-pr...
Article
A three-dimensional model of interstitial fluid flow and passive species transport within mineralized regions surrounding cross-cortical vessel canals is developed. In contrast to earlier studies, the present model applies to circulatory, non-stress-induced interstitial flow in porous cortical bone. Based on previous experimental observations, the...
Article
A leading order solution for thermocapillary, buoyancy, and shear-driven flow within a thin, fixed-length, annular fluid collar is determined. The solution is based on the assumption that , where C is the capillary number and ε is the collar aspect ratio. In contrast to earlier models of flow within bridges, boundary layer matching near the end reg...
Article
An inverse finite element method for solution of unknown multidimensional phase-change and material boundary shapes is presented. The method is based on minimization and requires boundary shape parametrization. The unknown boundary parameters are determined by minimizing the error between a limited number of known (e.g. measured) temperatures and t...
Conference Paper
A mathematical model is developed which describes cortical bone fluid flow and species transport in the vicinity of several in-bone vessel canals. Model simulations are qualitatively consistent with experimental observations and indicate that solute contact with the surrounding bone is approximately 85 percent complete when vessel canal radii are l...
Conference Paper
Full-text available
Investigates the effect of anisotropic permeability on fluid flow and passive non-diffusive species transport in cortical bone. A model is developed which focuses on flow and transport induced by a single blood vessel within a porous anisotropic matrix. Model predictions are found to be qualitatively consistent with experimental observations. More...
Article
Stress-induced fluid flow within individual osteons is modeled using a perturbation technique. In contrast to earlier models, the first order solution shows that flow within the mineralized matrix can occur in the longitudinal direction, suggesting a possible non-canalicular osteocytic nutrient supply route. The model also suggests that stress-indu...
Article
A three-dimensional finite element model of the plasma arc welding process is presented. The model allows calculation of the weld pool's approximate capillary and solid-liquid phase boundaries, the weld pool's three-dimensional flow and temperature fields, and the solid phase temperature distribution. Taking into account thermocapillary, jet shear,...
Article
A finite element-based simulation of the plasma arc welding process is presented. The simulation determines the weld pool's three-dimensional capillary surface shape, the approximate solid-liquid phase boundary, and calculates the pool's three-dimensional flow and temperature fields. The simulation is first used to examine the effect of ambient tem...
Article
Full-text available
This paper describes a general technique for optimizing cryosurgical procedures. The method, which is based on the simplex minimization algorithm, minimizes unnecessary freezing by optimizing various surgical parameters. The optimization procedure is illustrated using a simplified model of prostatic cryosurgery. In this illustrative case, the funct...
Article
Full-text available
A first order study of the interfacial (keyhole) shape between a penetrating argon plasma arc jet and a stationary liquid metal weld pool is presented. The interface is determined using the Young-Laplace equation by assuming that the plasma jet behaves as a one-dimensional ideal gas flow and by neglecting flow within the weld pool. The solution for...
Article
The pressure probe was used to conduct in vivo creep and in vivo stress relaxation experiments on the sporangiophores of Phycomyces blakesleeanus. The in vivo creep and in vivo stress relaxation methods are compared with respect to their utility for determining the irreversible wall extensibility and the yield threshold. The results of the in vivo...
Article
Abstract— The turgor pressure of the stage 4b sporangiophore of Phycomyces blakesleeanus was continuously measured with a pressure probe before and during a period of increased elongational growth rate elicited by a step-up in blue light fiuence rate (a positive light growth response) or by a double-barrier stimulus (avoidance growth response). In...