Cameron Tropea

Bio: Cameron Tropea is an academic researcher from Technische Universität Darmstadt. The author has contributed to research in topics: Drop (liquid) & Plasma actuator. The author has an hindex of 60, co-authored 567 publications receiving 18910 citations. Previous affiliations of Cameron Tropea include Lehigh University & University of Erlangen-Nuremberg.

Light Scattering from Small Particles

Abstract: In the laser Doppler and phase Doppler techniques a part of the incident laser light is imaged by the particles onto the detectors. It is this scattered light which carries information about the particle velocity and its properties and thus, the light scattered from small particles plays a central role in the basic physics of these measurement techniques. In recognition of this, the following chapter is devoted to the fundamentals of elastic light scattering from small particles. The simplest case of a homogeneous and isotropic sphere is considered.

Springer Handbook of Experimental Fluid Mechanics

Abstract: Introduction The expression: "analytical work", often connotes an effort in which basic expressions are combined to analyze a given problem and to derive new information and insight from the resulting mathematical steps of the analysis. Specifically, having started with the appropriate relationships and bringing appropriate mathematical manipulations to the task, the analyst is able to create new information to address the motivating question(s). A central organizing theme of this handbook is that 'experimental fluid mechanics" can be understood as a parallel activity to that described above. The motivating questions will set the context for the experiment. The experiment will be established as a boundary value problem in which the experimentalist will address all aspects of the boundary conditions that will influence the "solution." If a transient or an evolving solution is sought, the appropriate initial conditions will similarly be addressed. Having established these conditions, the solution to the boundary value problem will be revealed in the experimental data that will - ideally - not be contaminated by unintended or unknown perturbing effects and that will be fully converged if statistical average values are sought. Part A Experiments in Fluid Mechanics The objective of Part A is to establish the fundamental concepts and equations that undergird experimental fluid mechanics. The first chapter: addresses both the governing equations and the constitutive equations for Newtonian and non-Newtonian fluids. Chapter 2 provides the systematic bases for model testing and the scaling of experimental results. Sections 2.1 through 2.7 derive similitude parameters (Reynolds number, Froude number, etc.) from the governing equations and the boundary conditions. Dimensional analysis (Sect. 2.2) provides a rational approach for the organization and interpretation of experimental data Sect. 2.3, self-similarity, documents known flow fields that exhibit this condition and it provides guidance on what other flows may exhibit this behavior. The encyclopedic presentation of examples will allow the reader to comprehend the universal features of both complete and incomplete self-similarity. Chap. 1 The Experiment as a Boundary-Value Problem Chap. 2 Nondimensional Representation of the Boundary-Value Problem Part B Measurement of Primary Quantities The objective of Part B is to provide specific information to the reader on the following primary quantities: material properties (Chap. 3), flow field properties (Chap. 4 - pressure, Chap. 5 - velocity, vorticity, Mach number, Chap. 6 - spatial density variations and Chap. 7 - temperature and heat flux) and forces and moments (Chap. 8). Chapter 3 is focused on providing quantitative information for the material properties, the sources of this information and the associated confidence levels for the given data. Chapters 4 through 8 provide comprehensive guidance to the reader on: i) the objectives, ii) the available equipment, iii) the utilization techniques, and iv) the post-processing of the primitive information for the stated quantities. Chap. 3 Material Properties: Measurement and Data Chap. 4 Pressure Measurement Systems Chap. 5 Velocity, Vorticity and Mach Number Chap. 6 Spatial Density Variations Chap. 7 Temperature, Concentration and Heat Flux Chap. 8 Forces and Moments Part C Specific Experimental Approaches Building on the previous two parts of this Springer Handbook, which have dealt with the fundamental concepts and equations that undergrid experimental fluid mechanics and the measurement of primary quantities, respectively, Part C addresses experimental fluid mechanics from an application point of view. According to application, often unique and specific forms of equipment, experimental procedure, or analysis and interpretation of results have been developed. It is the purpose of Part C to elucidate a selection of such application areas, in particular measurements of non-Newtonian flows, turbulence, flow visualization, wall-bounded flows, surface topology, turbomachines, hydraulics, aerodynamics, atmospheric and oceanographic measurements, combustion diagnostics and electrohydrodynamic systems. Chap. 9 Non-Newtonian Flows Chap. 10 Measurement of Turbulent Flows Chap. 11 Flow Visualization Chap. 12 Wall-Bounded Flows Chap. 13 Surface Topology Chap. 14 Turbomachines Chap. 15 Hydraulics Chap. 16 Aerodynamics Chap. 17 Atmospheric Measurements Chap. 18 Oceanographic Measurements Chap. 19 The No-Slip Boundary Condition Chap. 20 Combustion Diagnostics Chap. 21 Electrohydrodynamic Systems Part D Analyses and Post-Processing of Data This final part of the Springer Handbook is actually meant to be a reference source about single and data processing techniques commonly encountered in fluid mechanics. These topics have been complemented by a section discussing data acquisition by imaging detectors, a topic becoming increasingly important for optical measurement techniques. These are all subjects, which in their development are not naturally associated with fluid mechanics hence Part D attempts to collect information from many diverse sources and present them conveniently to the fluid mechanic researcher. Topics covered in this part include fundamental topics of signal and data processing transforms (Fourier, Hilbert, wavelet), proper orthogonal decomposition and stochastic estimation. This is followed by a discussion of estimator expectation and variance and the influence of noise on these quantities. The Cramer-Rao Lower Bound (CRLB) is introduced and developed for several common signal processing examples from fluid mechanics. Imaging detectors and measures of their performance are then discussed in detail before closing with a chapter on image processing and motion analysis, two topics especially relevant for the Particle Image Velocity (PIV) measurement technique. Chap. 22 Review of Some Fundamentals Chap. 23 Fundamentals of Data Processing Chap. 24 Data Acquisition Chap. 25 Data Analyses About the Authors Subject Index

Time evolution of liquid drop impact onto solid, dry surfaces

Abstract: The normal impact of liquid drops onto solid, dry surfaces has been studied experimentally, using high-resolution digital photography. A large number of parameters were varied in a systematic manner. The focus of this paper is the quantitative determination of the influence of these parameters on the drop spreading upon impact and on the phenomenological description of the outcomes. Dimensional similarity of the spreading can only be achieved for the very early stage of the impact process. At later stages, the number of influencing factors increases, generally precluding any universal correlation. Particular emphasis is placed on the influence of the wettability and the surface roughness on spreading.

Boundary Layer Theory

Abstract: The boundary layer equations for plane, incompressible, and steady flow are $$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Fano resonances in nanoscale structures

Abstract: Modern nanotechnology allows one to scale down various important devices (sensors, chips, fibers, etc.) and thus opens up new horizons for their applications. The efficiency of most of them is based on fundamental physical phenomena, such as transport of wave excitations and resonances. Short propagation distances make phase-coherent processes of waves important. Often the scattering of waves involves propagation along different paths and, as a consequence, results in interference phenomena, where constructive interference corresponds to resonant enhancement and destructive interference to resonant suppression of the transmission. Recently, a variety of experimental and theoretical work has revealed such patterns in different physical settings. The purpose of this review is to relate resonant scattering to Fano resonances, known from atomic physics. One of the main features of the Fano resonance is its asymmetric line profile. The asymmetry originates from a close coexistence of resonant transmission and resonant reflection and can be reduced to the interaction of a discrete (localized) state with a continuum of propagation modes. The basic concepts of Fano resonances are introduced, their geometrical and/or dynamical origin are explained, and theoretical and experimental studies of light propagation in photonic devices, charge transport through quantum dots, plasmon scattering in Josephson-junction networks, and matter-wave scattering in ultracold atom systems, among others are reviewed.

Light Absorption by Carbonaceous Particles: An Investigative Review

Abstract: The optical properties of the light-absorbing, carbonaceous substance often called “soot,” “black carbon,” or “carbon black" have been the subject of some debate. These properties are necessary to model how aerosols affect climate, and our review is targeted specifically for that application. We recommend the term light-absorbing carbon to avoid conflict with operationally based definitions. Absorptive properties depend on molecular form, particularly the size of sp 2-bonded clusters. Freshly-generated particles should be represented as aggregates, and their absorption is like that of particles small relative to the wavelength. Previous compendia have yielded a wide range of values for both refractive indices and absorption cross section. The absorptive properties of light-absorbing carbon are not as variable as is commonly believed. Our tabulation suggests a mass-normalized absorption cross section of 7.5 ± 1.2 m2/g at 550 nm for uncoated particles. We recommend a narrow range of refractive indices for s...

Drop Impact Dynamics: Splashing, Spreading, Receding, Bouncing ...

Abstract: The review deals with drop impacts on thin liquid layers and dry surfaces. The impacts resulting in crown formation are referred to as splashing. Crowns and their propagation are discussed in detail, as well as some additional kindred, albeit nonsplashing, phenomena like drop spreading and deposition, receding (recoil), jetting, fingering, and rebound. The review begins with an explanation of various practical motivations feeding the interest in the fascinating phenomena of drop impact, and the above-mentioned topics are then considered in their experimental, theoretical, and computational aspects.