Pulsed ultrasound Doppler velocimetry proved to be capable of measuring velocities accurately (relative error less than 0.5 percent). In this research, the limitations of the method are investigated when measuring: in channels with a small thickness compared to the transducer diameter, at low velocities and in the presence of a flow reversal area. A review of the fundamentals of pulsed ultrasound Doppler velocimetry reveals that the accuracy of the measured velocity field mainly depends on the shape of the acoustic beam through the flow field and the intensity of the echo from the incident particles where the velocity is being measured. The ultrasonic transducer turned out to be most critical component of the system. Fundamental limitations of the method are identified. With ultrasonic beam measurements, the beam shape and echo intensity is further investigated. In general, the shape of the ultrasonic beam varies depending on the frequency and diameter of the emitter as well as the characteristics of the acoustic interface that the beam encounters. Moreover, the most promising transducer to measure velocity profiles in small channels is identified. Since the application of pulsed ultrasound Doppler velocimetry often involves the propagation of the ultrasonic burst through Plexiglas, the effect of Plexiglas walls on the measured velocity profile is analyzed and quantified in detail. The transducers ringing effect and the saturation region caused by highly absorbing acoustic interfaces are identified as limitations of the method. By comparing measurement results in the small rectangular channel to numerically calculated results, further limitations of the method are identified. It was not possible to determine velocities correctly throughout the whole channel at low flow rates, in small geometries and in the flow separation region. A discrepancy between the maximum measured velocity, velocity profile perturbations and incorrect velocity determination at the far channel wall were main shortcomings. Measurement results are improved by changes in the Doppler angle, the flow rate and the particle concentration. Suggestions to enhance the measurement system, especially its spatial resolution, and to further investigate acoustic wave interactions are made.

Application of Pulsed Ultrasonic Doppler Velocimetry to the Simultaneous Measurement of Velocity and Concentration Profiles in Two Phase Flow.

The Light Metals symposia at the TMS Annual Meeting & Exhibition present the most recent developments, discoveries, and practices in primary aluminum science and technology. The annual Light Metals volume has become the definitive reference in the field of aluminum production and related light metal technologies. The 2018 collection includes papers from the following symposia: 1.Alumina and Bauxite2.Aluminum Alloys, Processing, and Characterization3.Aluminum Reduction Technology4.Cast Shop Technology5. Cast Shop Technology: Energy Joint Session6. Cast Shop Technology: Fundamentals of Aluminum Alloy Solidification Joint Session7. Cast Shop Technology: Recycling and Sustainability Joint Session8. Electrode Technology for Aluminum Production9. Perfluorocarbon Generation and Emissions from Industrial Processes10. Scandium Extraction and Use in Aluminum Alloys

The ultrasonic velocity profile (UVP) method, first developed in medical engineering, is now widely used in clinical settings. The fluid mechanical basis of UVP was established in investigations by the author and his colleagues with work demonstrating that UVP is a powerful new tool in experimental fluid mechanics. There are diverse examples, ranging from problems in fundamental fluid dynamics to applied problems in mechanical, chemical, nuclear, and environmental engineering. In all these problems, the methodological principle in fluid mechanics was converted from point measurements to spatio-temporal measurements along a line. This book is the first monograph on UVP that offers comprehensive information about the method, its principles, its practice, and applied examples, and which serves both current and new users. Current users can confirm that their application configurations are correct, which will help them to improve the configurations so as to make them more efficient and effective. New users will become familiar with the method, to design applications on a physically correct basis for performing measurements accurately. Additionally, the appendix provides necessary practical information, such as acoustic properties.

A description of the physical principles upon which Doppler ultrasound is based and the instrumentation and processing necessary to measure and record the flows from within the body. Clinical applications are surveyed to demonstrate the method's potential and illustrate technical data.

A clear, extensively illustrated treatment of ultrasound systems used in estimating blood velocities.

Ultrasound Doppler Velocimetry (UDV) is a promising non-invasive technique in applications of both practical and scientific flow measurements. Generally UDV measurements of steady-state and laminar flows are encountered in the literature. Capacity of the technique in the measurement of complex flows must be examined. This will allow us to adapt UDV for the monitoring of complex flows and fluids. Therefore interactions of some complex flow mediums with UDV signals are investigated mathematically and experimentally in this book. Oscillating, turbulent/random velocity and linear viscoelastic flows are considered accordingly. Analysis of oscillating flows revealed the limitations of this technique for the measurement of such flows. UDV signals were utilized to obtain statistical properties of random velocity functions/pipe turbulence. Linear viscoelastic fluids and determination of their properties (complex viscosity, relaxation spectrum) by UDV measurements are considered theoretically in the last part of the book. Basics of UDV, digital signal processing, random processes, turbulent and viscoelastic flows are included in the manuscript to assist the reader.

"Color Doppler Ultrasound (CDUS) is a method of non-invasive fluid velocity measurement that is used for regular cardiac screenings as well as during complex surgeries such as valve replacements. A Color Doppler image is a contour map of the velocity field and can thereby indicate the presence of abnormal flows or be used to quantitatively measure velocities. CDUS is inexpensive and completely non-invasive. It is for these same reasons that CDUS has the potential to be a powerful tool not only in the medical field, but in the industrial and engineering research fields as well. While there are many devices that use ultrasonic transducers to determine either pipe-wall corrosion or mean flow rate, to date making accurate velocity measurements has required either a clear visualization section or an invasive form of measurement. An experimental method to quantify the accuracy of Color Doppler Ultrasound velocity measurements in both the laminar and turbulent flow regime through a non-biological media is presented. A clear acrylic tube with a conical nozzle, throat, and a sudden expansion is used to generate a well characterized flow field that includes features typical of physiologic flows and flows within medical devices such as high speed jets and recirculation. The velocity field is measured at three locations using both Color Doppler Ultrasound and Particle Image Velocimetry (PIV) and the measurements are used to generate velocity profiles, which are compared quantitatively. It was found that although it is possible to resolve phenomena such as recirculation and high speed jets, the media through which the imaging occurs has a significant impact on the accuracy of the Ultrasound generated velocity measurements. Due to the large amount of attenuation of sound through acrylic media, the Color Doppler readings show significant error in velocity measurements. For laminar parabolic flows this shifts both the mean and peak velocities down, with a percent difference in both as high as 42% and 55% respectively. However, at the sudden expansion where high speed jets and recirculation zones occur, the velocity profile becomes wider and flatter, and though the peak velocity measurements have a percent difference of approximately 50%, the percent difference in the mean velocity varied from less than 1% to a maximum of 10%."--Abstract.