Recently, granules under vertical vibrations receive many attentions due to their importance in theoretical research and engineering application. In this paper, a two-dimensional Particle Image Velocimetry (PIV) system was used to examine the f/2 stripe pattern forming in a vertically vibrated granular layer. Since the PIV sampling frequency does not match with the vibrating frequency, a special identification-coupling method was adopted to combine the images taken in different cycles to offer the information in one complete cycle. The measured velocity vectors showed exactly the particle motions at various stages of a motion cycle, illustrating the alternating peaks and valleys on the layer top. Furthermore, quantitative results on the temporal evolution of velocity profiles were obtained and some other interesting phenomena were observed, such as the appearance of local structures (e.g. dual-phase layer structure) and the moving feature of the 'standing point'. The mechanism accounting for the occurrence of stripes on the surface is also discussed. This work will be of interest to a better understanding on pattern formation in the vibrating granular bed. / Singapore-MIT Alliance (SMA)

The overarching objective of this research project was to gain improved basic understanding of the fluid mechanisms governing the development of secondary flow structures in complex, three-dimensional inlet ducts. To accomplish this objective, particle image velocimetry measurements were employed to document the mean and turbulent flow properties within the complex flow regions. Complimentary, surface oil flow visualizations and static pressures were obtained to aid in the interpretation of the PIV data. Using these diagnostic techniques, the formation of a pair of counter-rotating vortices was revealed. Two-dimensional PIV measurements were conducted along 20 planes near the two bends of the duct model. All data was collected with an incoming freestream of 40 m/s. Over 2000 image pairs were collected for each measurement location, which were then processed and averaged to generate mean velocity, variance intensity, and velocity gradient statistics. The data was analyzed and it was determined that the experimental PIV data corresponded well with the qualitative flow visualization. This research will contribute to the particle image velocimetry database and subsequent analyses, which will provide additional insight into the flow structure and provide a new database for numerical model validation.

El objetivo principal de esta tesis es la mejora y la aplicación de la técnica PIV para analizar diferentes flujos de fluidos complejos en los sistemas que contienen partes sólidos móviles o estacionarias. Las partículas de alginato con/sin compuesto de fluoresceína incrustada se han desarrollado como una serie de elementos alternativos de siembra de nuevas aplicaciones de flujo para el PIV. Se ha encontrado que las micro-partículas de alginato tienen muchas ventajas sobre los tradicionales utilizados en sistemas de PIV. Un estudio amplio sobre el análisis del flujo en tres dimensiones de la bomba de engranajes externa se ha hecho por la técnica tiempo-resuelva PIV para investigar la dinámica y las estadísticas de flujo turbulento. Vorticidad y zonas turbulentas de alta energía cinética se han identificado dentro de la bomba de engranajes externa. La técnica PIV se ha aplicado de manera eficiente para analizar un intercambiador de calor de motor de flujo de bypass en un túnel del viento de bajo velocidad. Las partículas de alginato que contienen fluoresceína se han utilizado eficientemente en los experimentos que conducen a mejorar la calidad de la imagen PIV y analizar las estructuras de pequeña escala de los flujos. / The main objective of the thesis is the improvement and application of the PIV technique to analyse different complex fluid flows in systems that contain solid moving or stationary parts. The alginate particles with/without fluorescein compound imbedded have been developed as a new alternative flow seeding elements for PIV applications. It has been found that the alginate micro particles have many advantages over traditional ones used in PIV systems. A comprehensive study on the three-dimensional flow analysis of the external gear pump has been done by time-resolved PIV technique to investigate its turbulent flow dynamics and statistics. Vorticity and high turbulent kinetic energy areas have been identified inside the external gear pump. The PIV technique has been efficiently applied to analyse an engine bypass flow heat exchanger in a low speed wind tunnel. The alginate particles containing fluorescein have been efficiently used in the experiments that lead to improve the PIV image quality and analyse the small-scale structures of the flows.

The overarching objective of this research project was to gain improved basic understanding of the fluid mechanisms governing the development of secondary flow structures in complex, three-dimensional inlet ducts. To accomplish this objective, particle image velocimetry measurements were employed to document the mean and turbulent flow properties within the complex flow regions. Complimentary, surface oil flow visualizations and static pressures were obtained to aid in the interpretation of the PIV data. Using these diagnostic techniques, the formation of a pair of counter-rotating vortices was revealed. Two-dimensional PIV measurements were conducted along 20 planes near the two bends of the duct model. All data was collected with an incoming freestream of 40 m/s. Over 2000 image pairs were collected for each measurement location, which were then processed and averaged to generate mean velocity, variance intensity, and velocity gradient statistics. The data was analyzed and it was determined that the experimental PIV data corresponded well with the qualitative flow visualization. This research will contribute to the particle image velocimetry database and subsequent analyses, which will provide additional insight into the flow structure and provide a new database for numerical model validation.

Thesis (M.S.)--Rutgers University, 2009. / "Graduate Program in Mechanical and Aerospace Engineering." Includes bibliographical references (p. 113-114).

Thesis (Ph. D.)--Chemical Engineering, Georgia Institute of Technology, 2004. / Ludovice, Peter, Committee Chair; Lee, Jay, Committee Member; Meredith, Carson, Committee Member; Morris, Jeff, Committee Member; Neitzel, Paul, Committee Member. Vita. Includes bibliographical references (leaves 120-123).

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: Noel T. Clemens Vita. Includes bibliographical references. Also available from UMI.

Thesis (Ph. D.)--Florida State University, 2004. / Advisor: Dr. Steven W. Van Sciver, Florida State University, College of Engineering, Department of Mechanical Engineering. Title and description from dissertation home page (viewed June 16, 2004). Includes bibliographical references.

Not available / text

published_or_final_version / Civil Engineering / Master / Master of Philosophy