Download or read book The Fluid Dynamics of Droplet Impact on Inclined Surfaces with Application to Forensic Blood Spatter Analysis written by G. Paul Neitzel and published by . This book was released on 2017 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Bloodstain pattern analysis is a technique used in crime-scene reconstruction to determine the point of origin of a blood droplet as well as the method of its creation, e.g., dripping, wiping, or low-to-high-speed impact caused by anything from blunt trauma to cast-off to gunshot wounds. The primary problem of interest in this analysis is to determine of the initial size, speed, and impact angle of a blood droplet that has struck a solid surface through an examination of the bloodstain pattern left on the surface. This research project addressed this problem using a detailed fluid dynamical study of the impact and spreading of a liquid droplet on planar surfaces of variable roughness, wettability, and absorbency oriented at various angles with respect to the velocity vector of the approaching droplet. In particular, this research used a coordinated program of laboratory experiments and numerical simulations to examine the influence of the many parameters associated with such droplet impacts. Given its importance to crime-scene reconstruction, the focus of this work is on how to use the shape of the final stain to determine the initial conditions of droplet impact."--Abstract.
Download or read book Blood Traces written by Peter R. De Forest and published by John Wiley & Sons. This book was released on 2021-08-06 with total page 387 pages. Available in PDF, EPUB and Kindle. Book excerpt: A guide to the scientific interpretation of blood traces Blood Traces provides an authoritative resource that reviews many of the aspects of the interpretation of blood traces that have not been treated with the thoroughness they deserve. With strict adherence to the scientific method, the authors — noted experts on the topic — address the complexities encountered when interpreting blood trace configurations. The book provides an understanding of the scientific basis for the use of blood trace deposits, i.e. bloodstain patterns, at crime scenes to better reconstruct a criminal event. The authors define eight overarching principles for the comprehensive analysis and interpretation of blood trace configurations. Three of these principles are: blood traces may reveal a great deal of useful information; extensive blood traces, although present, may not always yield information relevant to questions that may arise in a given case; and a collection of a few seemingly related dried blood droplet deposits is not necessarily an interpretable “pattern”. This important resource: Provides the fundamental principles for the scientific examination and understanding of blood trace deposits and configurations Dispels commonly accepted misinformation about blood traces. Contains a variety of illustrative case examples which will aid in demonstrating the concepts discussed Written for forensic scientists, crime scene investigators, members of the legal community, and students in these fields, Blood Traces presents the fundamental principles for the scientific examination of blood trace deposits and configurations.
Download or read book Introduction to Forensic Science written by James T. Spencer and published by CRC Press. This book was released on 2024-10-07 with total page 775 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction to Forensic Science: The Science of Criminalistics is a textbook that takes a unique and holistic approach to forensic science. This book focuses on exploring the underlying scientific concepts as presented at the introductory college and senior high school levels. Chapters introduce readers to each of the important areas of forensic science, grouping chapters together by discipline and following a logical progression and flow between chapters. This systematically allows students to understand the fundamental scientific concepts, recognize their various applications to the law and investigations, and discern how each topic fits broadly within the context of forensic science. The writing is accessible throughout, maintaining students’ interest – including both science and non-science majors – while inspiring them to learn more about the field. Concepts are demonstrated with numerous case studies and full-color illustrations that serve to emphasize the important ideas and issues related to a particular topic. This approach underscores scientific understanding, allowing the student to go beyond simple rote learning to develop deeper insights into the field, regardless of their scientific background. This book has been extensively classroom-tested to provide the most comprehensive and up-to-date survey of various forensic disciplines and the current state of the science, policies, and best practices. Key features: Presents a wholly new, fresh approach to addressing a broad survey of techniques and evidentiary analyses in the field of forensic science. All concepts – and the underpinnings of forensic practice – are explained in simple terms, using understandable analogies and illustrations to further clarify concepts. Introduces topics that other introductory texts fail to address, including serology, behavioral science, forensic medicine and anthropology, forensic ecology, palynology, zoology, video analysis, AI/computer forensics, and forensic engineering. Highly illustrated with over 1,000 full-color photographs, drawings, and diagrams to further highlight key concepts. Suitable for both high school senior-level instruction and two- and four-year university courses for majors, non-majors, and criminal justice students enrolled in introductory forensic science classes. Support Materials – including an Instructor’s Manual with test bank and chapter PowerPoint lecture slides – are available to professors with qualified course adoption.
Download or read book Analysis of Droplet Impact Onto Horizontal and Inclined Surfaces written by Šefko Šikalo and published by . This book was released on 2003 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Drop Surface Interactions written by Martin Rein and published by Springer. This book was released on 2014-05-04 with total page 317 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a comprehensive overview of fluid mechanical, thermal and physico-chemical aspects of drop-surface interactions. Basic physical mechanisms pertaining to free-surface flow phenomena characteristic of drop impact on solid and liquid surfaces are explained emphasizing the importance of scaling. Moreover, physico-chemical fundamentals relating to a forced spreading of complex solutions, analytical tools for calculating compressibility effects, and heat transfer and phase change phenomena occurring during solidification and evaporation processes, respectively, are introduced in detail. Finally, numerical approaches particularly suited for modeling drop-surface interactions are consisely surveyed with a particular emphasis on boundary integral methods and Navier-Stokes algorithms (volume of fluid, level set and front tracking algorithms). The book is closed by contributions to a workshop on Drop-Surface Interactions held at the International Centre of Mechanical Sciences.
Download or read book Droplet Interactions and Spray Processes written by Grazia Lamanna and published by Springer Nature. This book was released on 2020-03-14 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a selection of contributions to the DIPSI workshop 2019 (Droplet Impact Phenomena & Spray Investigations) as well as recent progress of the Int. Research Training Group “DROPIT”.The DIPSI workshop, which is now at its thirteenth edition, represents an important opportunity to share recent knowledge on droplets and sprays in a variety of research fields and industrial applications. The research training group “DROPIT” is focused on droplet interaction technologies where microscopic effects influence strongly macroscopic behavior. This requires the inclusion of interface kinetics and/or a detailed analysis of surface microstructures. Normally, complicated technical processes cover the underlying basic mechanisms, and therefore, progress in the overall process modelling can hardly be gained. Therefore, DROPIT focuses on the underlying basic processes. This is done by investigating different spatial and/or temporal scales of the problems and by linking them through a multi-scale approach. In addition, multi-physics are required to understand e.g. problems for droplet-wall interactions, where porous structures are involved.
Download or read book Dynamics of Droplets written by Arnold Frohn and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book deals with the dynamical behaviour of single droplets and regular droplet systems. It has been written mainly for experimental researchers. After a short description of the theoretical background, the different experimental facilities and methods necessary for the investigation of single droplets are described in detail. A summary of important applications is included.
Download or read book Investigation of Blood Dynamics written by Nik Elena Nik Mohamed and published by . This book was released on 2009 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is divided into two parts, each of which examines aspects of bloodstain analysis where gravity is the main force applied to blood. Part I is a preliminary study on the dynamics of blood flow on various inclined surfaces and examines the use of blood analogs for easy test replication. The flow of uncoagulated human blood at different volumes and temperatures was examined on wood at a set angle of 1.5°, and on glass at varying incline angles. Glycerol solutions of 59% and 42% were used to represent blood at 23°C and 37°C respectively. Glycerol flow trials of similar volumes were conducted on wood, PVC and glass. Fluid flow plots of distance versus time exhibited double exponential curve behaviour, although a power-law relationship derived by H. E. Huppert's (1982) flow expression was obtained for blood flowing on inclined wood. Blood flow exhibited several observable characteristics; a decreasing width of the leading edge over time, and streaking and component separation of the leading region at very low speeds. On a glass surface, the width of the initial flow region decreased and initial speed increased with increasing angles. The glycerol analogs used in this study did not represent their blood counterparts well due to differences in physical properties of the fluids. Part II of this study focuses on the forensic value of passive bloodstains on three fabrics; 100% cotton drill, 65/35 polyester cotton, and 100% Shantung silk. 26 oL drops of 37°C human blood were deposited onto the three fabrics and paper from a height of 14 cm at various impact angles. The stains were photographed and analysed qualitatively and quantitatively using computational methods. 100% cotton drill, 65/35 polyester cotton and ironed 100% Shantung silk provided useful forensic values such as direction of travel and angle of impact. Overall, this study has provided useful preliminary data for further research work.
Download or read book Blood Droplet Dynamics I written by PA. Pizzola and published by . This book was released on 1986 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The interpretation of bloodstain patterns at crime scenes has received increased attention in recent years. Important to an understanding of this is knowledge of the fundamentals of blood droplet formation and impact dynamics. A review of the literature reveals that a considerable amount of work has been done with aqueous drop dynamics. Workers in the forensic science area seem to have been unaware of this. In addition, some of the most important and comprehensive early work with blood droplet dynamics seems to have been forgotten. It is not cited in more recent publications dealing with bloodstain pattern interpretation. This literature is reviewed and discussed as well. The present study presents results of experiments with blood droplet dynamics and high-speed photographs of blood droplet impacts on stationary target surfaces. Some longstanding misconceptions of importance to forensic scientists engaged in crime scene reconstruction are discussed.
Download or read book Droplet Dynamics Under Extreme Ambient Conditions written by Kathrin Schulte and published by Springer Nature. This book was released on 2022 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book presents the main results of the Collaborative Research Center SFB-TRR 75, which spanned the period from 2010 to 2022. Scientists from a variety of disciplines, ranging from thermodynamics, fluid mechanics, and electrical engineering to chemistry, mathematics, computer science, and visualization, worked together toward the overarching goal of SFB-TRR 75, to gain a deep physical understanding of fundamental droplet processes, especially those that occur under extreme ambient conditions. These are, for example, near critical thermodynamic conditions, processes at very low temperatures, under the influence of strong electric fields, or in situations with extreme gradients of boundary conditions. The fundamental understanding is a prerequisite for the prediction and optimisation of engineering systems with droplets and sprays, as well as for the prediction of droplet-related phenomena in nature. The book includes results from experimental investigations as well as new analytical and numerical descriptions on different spatial and temporal scales. The contents of the book have been organised according to methodological fundamentals, phenomena associated with free single drops, drop clusters and sprays, and drop and spray phenomena involving wall interactions.
Download or read book Blood Droplet Dynamics II written by PA. Pizzola and published by . This book was released on 1986 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: An earlier companion paper to the present one dealt with a literature review as well as blood droplet formation and impacts to stationary target surfaces. The present paper discusses the results of experiments with moving target surfaces. These are discussed in the context of their correlation with blood droplet impacts to inclined stationary targets and with respect to the interpretation of bloodstain patterns at crime scenes where the target surface is capable of its own movement. A special belt device was designed and constructed for the experiments reported here. This motorized apparatus was used to drive paper belt target surfaces at various controlled speeds.
Download or read book A study of droplet deformation written by Hannah Fry and published by Lulu.com. This book was released on 2012-09-14 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: In both engineering and medical applications it is often useful to use the knowledge of the conditions under which adhering liquid droplets appear, deform and interact with surrounding fluids, in order to either remove or create them. Examples include the de-wetting of aircraft surfaces and the process of injecting glue into the bloodstream in the treatment of aneurysms. In this study, we look at various methods of modelling a particular class of droplets - those attached to a wall in the presence of an external shear flow.
Download or read book Experimental Investigation of Droplet Impact Dynamics on Solid Surfaces written by Kalpak Prakash Gatne and published by . This book was released on 2006 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study of the normal impact of liquid droplets on a dry horizontal substrate is presented in this thesis. The impact dynamics, spreading and recoil behavior are captured using a high-speed digital video camera at 2000 frames per second. A digital image processing software was used to determine the drop spread and height of the liquid on the surface from each frame. To ascertain the effects of liquid viscosity and surface tension, experiments were conducted with four pure liquids (water, ethanol, propylene glycol and glycerin) that have vastly different fluid properties. Three different Weber numbers (20, 40, and 80) were considered by altering the height from which the drop is released. To understand the influence of drop size, experiments were performed in which the drop size was varied for the same fluid. Also, the effect of substrate material was studied by comparing the impact on two different substrates: glass (hydrophilic) and PTFE or Teflon (hydrophobic). The high-speed photographs of impact, spreading and recoil are shown and the temporal variations of dimensionless drop spread and height are provided in the paper. Experiments were performed to study the influence of addition of surface active agents or surfactants in aqueous solution on the droplet impact phenomenon. Three surfactants were used with varying diffusion rates: SDS (anionic), CTAB (cationic) and Triton x 100 (non ionic). The spreading and recoil of the drops of surfactant solutions is studied at concentrations of half the critical micelle concentration (CMC) and twice CMC. To underscore the dynamic effects, comparative experiments for the three surfactants were performed so that all the solutions had the same value of equilibrium surface tension. The role played by impact velocity in the collision of surfactant laden drops was studied by comparing the results for two different impact velocities. The influence of surfactant concentration was studied by performing experiments varying the surfactant concentrations. The results show that changes in liquid viscosity, surface tension, and surfactant concentration significantly affect the spreading and recoil behavior. In the case of pure liquids, for a fixed Weber number, lower surface tension promotes greater spreading and higher viscosity dampens spreading and recoil. Using a simple scale analysis of energy balance, it was found that the maximum spread factor varies as Re 1/5when liquid viscosity is high and viscous effects govern the spreading behavior. The drop size had no binding when the Weber number was maintained constant and the Reynolds numbers were comparable. The nature of the substrate plays a very important role. Impact on hydrophobic substrates can result in dramatic recoils and rebound. For aqueous solutions with surface active agents, it was observed that higher diffusion rate surfactants result in higher spreading factors and weaker oscillations. The spreading and recoil behavior can be correlated to the dynamic surface tension response of the surfactant solutions. With increase in impact velocity, the gain in spreading factor over a pure water drop decreases. Also, lowering of the surfactant concentration results in lower spreading factor and stronger recoil - a behavior closer to that of pure water.
Download or read book Drop Dynamics and Dropwise Condensation on Textured Surfaces written by Sameer Khandekar and published by Springer. This book was released on 2021-09-13 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an expanded form of the monograph, Dropwise Condensation on Inclined Textured Surfaces, Springer, 2013, published earlier by the authors, wherein a mathematical model for dropwise condensation of pure vapor over inclined textured surfaces was presented, followed by simulations and comparison with experiments. The model factored in several details of the overall quasi-cyclic process but approximated those at the scale of individual drops. In the last five years, drop level dynamics over hydrophobic surfaces have been extensively studied. These results can now be incorporated in the dropwise condensation model. Dropwise condensation is an efficient route to heat transfer and is often encountered in major power generation applications. Drops are also formed during condensation in distillation devices that work with diverse fluids ranging from water to liquid metals. Design of such equipment requires careful understanding of the condensation cycle, starting from the birth of nuclei, followed by molecular clusters, direct growth of droplets, their coalescence, all the way to instability and fall-off of condensed drops. The model described here considers these individual steps of the condensation cycle. Additional discussions include drop shape determination under static conditions, a fundamental study of drop spreading in sessile and pendant configurations, and the details of the drop coalescence phenomena. These are subsequently incorporated in the condensation model and their consequences are examined. As the mathematical model is spread over multiple scales of length and time, a parallelization approach to simulation is presented. Special topics include three-phase contact line modeling, surface preparation techniques, fundamentals of evaporation and evaporation rates of a single liquid drop, and measurement of heat transfer coefficient during large-scale condensation of water vapor. We hope that this significantly expanded text meets the expectations of design engineers, analysts, and researchers working in areas related to phase-change phenomena and heat transfer.
Download or read book Drop Impact on an Inclined and a Moving Surface written by Salman Buksh Sookran and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis has made progress in two different areas related to drop impact onto a surface. Firstly, a systematic experimental study has been performed to understand asymmetric spreading of low and high surface tension liquids on a moving surface. A new time evolution model for droplet spreading on a moving surface was developed. This model regardless the value of surface tension of the liquid can predict the spreading of low viscous (1-4cSt) liquids on a moving surface. Secondly, liquids with viscosity (1-5cSt) and surface tension (17.4-72.8mNm) were used to study the drop impact on moving and inclined surface. Experiments performed with similar normal (0.9-2.9m/s) and tangential (0.8-2.9m/s) velocities on both surfaces to test our hypothesis that spreading/splashing for these two surface conditions should be same. Results indicates that our hypothesis is true, except for some special conditions when, normal and tangential velocities are greater than the range of our analysis.
Download or read book Fundamental Research and Application of Droplet Dynamics written by Hongliang Luo and published by Intechopen. This book was released on 2022-11-02 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book examines the fundamental research and application of droplet dynamics. It includes six chapters in four sections. Section 1 introduces the concepts of droplet dynamics in powertrain systems. Section 2 reviews the optical methods for investigations in droplet dynamics. Section 3 examines the fundamental research on liquid droplet behaviors, such as droplet impact in internal combustion engines and the movement of liquid droplets in atmospheric pressure plasmas. Finally, Section 4 deals with the application of droplet behaviors not only in spray and combustion but also in bioinspired smart surfaces. The information contained herein is useful for engineers and students looking to broaden their knowledge of droplet behaviors and dynamics, especially for their development and application in low-carbon engines.
Download or read book An Investigation of the Evaporation of a Droplet on a Solid Surface Evaporation Self Assembly of Colloidal Deposits and Interfacial Heat Transfer written by Rajneesh Bhardwaj and published by . This book was released on 2010-02-01 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: The high, fast and local heat transfer associated with the deposition and evaporation of a single droplet on a flat surface has potential applications in spray evaporative cooling. Controlled evaporation of microdroplets containing colloidal particles can be used to manufacture nanowires, explosive crystalline layers and DNA spots for gene expression analysis. The physics of this phenomenon is a complex interplay of fluid dynamics in presence of a severely deforming free surface, wetting line motion, convective and conductive heat transfer, mass transfer due to evaporation and advection-diffusion of particles inside the droplet. In this book, Rajneesh Bhardwaj proposes a numerical modeling to investigate the interplay of transport phenomena during droplet impact and evaporation, for the case of a pure liquid or a colloidal solution. Comparions of numerical results with available or in-house experiments are made wherever possible.
