The Experts below are selected from a list of 43656 Experts worldwide ranked by ideXlab platform

Ivan Marusic - One of the best experts on this subject based on the ideXlab platform.

Jerry Westerweel - One of the best experts on this subject based on the ideXlab platform.

  • Particle Image Velocimetry for complex and turbulent flows
    Annual Review of Fluid Mechanics, 2013
    Co-Authors: Jerry Westerweel, G. E. Elsinga, Ronald J Adrian
    Abstract:

    Particle Image Velocimetry (PIV) has evolved to be the dominant method for Velocimetry in experimental fluid mechanics and has contributed to many advances in our understanding of turbulent and complex flows. In this article we review the achievements of PIV and its latest implementations: time-resolved PIV for the rapid capture of sequences of vector fields; tomographic PIV for the capture of fully resolved volumetric data; and statistical PIV, designed to optimize measurements of mean statistical quantities rather than instantaneous fields. In each implementation, the accuracy and spatial resolution are limited. To advance the method to the next level, we need a completely new approach. We consider the fundamental limitations of two-pulse PIV in terms of its dynamic ranges. We then discuss new paths and developments that hold the promise of achieving a fundamental reduction in uncertainty.

  • micro Particle Image Velocimetry µpiv recent developments applications and guidelines
    Lab on a Chip, 2009
    Co-Authors: Ralph Lindken, Massimiliano Rossi, S Grose, Jerry Westerweel
    Abstract:

    In this review we discuss the state of the art of the optical whole-field velocity measurement technique micro-scale Particle Image Velocimetry (µPIV). µPIV is a useful tool for fundamental research of microfluidics as well as for the detailed characterization and optimization of microfluidic applications in life science, lab-on-a-chip, biomedical research, micro chemical engineering, analytical chemistry and other related fields of research. An in depth description of the µPIV method is presented and compared to other flow visualization and measurement methods. An overview of the most relevant applications is given on the topics of near-wall flow, electrokinetic flow, biological flow, mixing, two-phase flow, turbulence transition and complex fluid dynamic problems. Current trends and applications are critically reviewed. Guidelines for the implementation and application are also discussed.

  • micro Particle Image Velocimetry micropiv recent developments applications and guidelines
    Lab on a Chip, 2009
    Co-Authors: Ralph Lindken, Massimiliano Rossi, Sebastian Grosse, Jerry Westerweel
    Abstract:

    In this review we discuss the state of the art of the optical whole-field velocity measurement technique micro-scale Particle Image Velocimetry (µPIV). µPIV is a useful tool for fundamental research of microfluidics as well as for the detailed characterization and optimization of microfluidic applications in life science, lab-on-a-chip, biomedical research, micro chemical engineering, analytical chemistry and other related fields of research. An in depth description of the µPIV method is presented and compared to other flow visualization and measurement methods. An overview of the most relevant applications is given on the topics of near-wall flow, electrokinetic flow, biological flow, mixing, two-phase flow, turbulence transition and complex fluid dynamic problems. Current trends and applications are critically reviewed. Guidelines for the implementation and application are also discussed.

Ronald J Adrian - One of the best experts on this subject based on the ideXlab platform.

  • Particle Image Velocimetry for complex and turbulent flows
    Annual Review of Fluid Mechanics, 2013
    Co-Authors: Jerry Westerweel, G. E. Elsinga, Ronald J Adrian
    Abstract:

    Particle Image Velocimetry (PIV) has evolved to be the dominant method for Velocimetry in experimental fluid mechanics and has contributed to many advances in our understanding of turbulent and complex flows. In this article we review the achievements of PIV and its latest implementations: time-resolved PIV for the rapid capture of sequences of vector fields; tomographic PIV for the capture of fully resolved volumetric data; and statistical PIV, designed to optimize measurements of mean statistical quantities rather than instantaneous fields. In each implementation, the accuracy and spatial resolution are limited. To advance the method to the next level, we need a completely new approach. We consider the fundamental limitations of two-pulse PIV in terms of its dynamic ranges. We then discuss new paths and developments that hold the promise of achieving a fundamental reduction in uncertainty.

  • dissipation estimation around a rushton turbine using Particle Image Velocimetry
    APS, 2000
    Co-Authors: Ronald J Adrian, Kendra V Sharp
    Abstract:

    Particle Image Velocimetry (PIV) measurements have been performed in a cylindrical tank stirred by a Rushton turbine. Two datasets were acquired in the r-z plane with magnification 0.26 and 0.56. Phase-averaged velocity fields and mean square gradients were calculated. The mean velocity field averaged over all blade positions is presented. The mean square gradients are used to estimate turbulent dissipation, e, in the measurement volumes. Two estimates of e are presented, one based only on \( \overline {u_{{1.1}}^{2},} \) and the other based on all of the available measured components. Both employ isotropic assumptions. The applicability of the isotropic assumptions is assessed by comparing the magnitudes of the mean square gradients, and the methods of dissipation estimation are compared. The normalized local dissipation, averaged over all blade positions, is calculated versus z for several values of r/R where R is the radius of the blade. The limitations of using PIV to calculate dissipation directly are addressed.

  • A Particle Image Velocimetry system for microfluidics
    Experiments in Fluids, 1998
    Co-Authors: Juan G. Santiago, Carl D Meinhart, Steven T Wereley, David J. Beebe, Ronald J Adrian
    Abstract:

    A micron-resolution Particle Image Velocimetry (micro-PIV) system has been developed to measure instantaneous and ensemble-averaged flow fields in micron-scale fluidic devices. The system utilizes an epifluorescent microscope, 100–300 nm diameter seed Particles, and an intensified CCD camera to record high-resolution Particle-Image fields. Velocity vector fields can be measured with spatial resolutions down to 6.9×6.9×1.5 μm. The vector fields are analyzed using a double-frame cross-correlation algorithm. In this technique, the spatial resolution and the accuracy of the velocity measurements is limited by the diffraction limit of the recording optics, noise in the Particle Image field, and the interaction of the fluid with the finite-sized seed Particles. The stochastic influence of Brownian motion plays a significant role in the accuracy of instantaneous velocity measurements. The micro-PIV technique is applied to measure velocities in a Hele–Shaw flow around a 30 μm (major diameter) elliptical cylinder, with a bulk velocity of approximately 50 μm s-1.

  • dynamic ranges of velocity and spatial resolution of Particle Image Velocimetry
    Measurement Science and Technology, 1997
    Co-Authors: Ronald J Adrian
    Abstract:

    To observe instantaneous fields of vorticity and rate-of-strain using PIV (Particle Image Velocimetry) measurements of the velocity field, it is necessary to achieve maximum dynamic ranges in space and in velocity while simultaneously making accurate, low-noise measurements for the differentiation process. In this paper the dynamic ranges achievable with PIV are established in the context of the super-resolution algorithm described previously which seeks to extract the maximum possible information from a Particle Image field. Bounds on the dynamic spatial range and the dynamic velocity range are established in terms of optical parameters, and simple rules are derived for optimum design of PIV optical systems for various types of Image recording media.

  • phase conjugate holographic system for high resolution Particle Image Velocimetry
    Applied Optics, 1994
    Co-Authors: Donald H Barnhart, Ronald J Adrian, George C Papen
    Abstract:

    A novel holographic Particle-Image velocimeter system has been developed for the study of three-dimensional (3-D) fluid velocity fields. The recording system produces 3-D Particle Images with a resolution, a signal-to-noise ratio, an accuracy, and derived velocity fields that are comparable to high-quality two-dimensional photographic Particle-Image Velocimetry (PIV). The high Image resolution is accomplished through the use of low f-number optics, a fringe-stabilized processing chemistry, and a phase conjugate play-back geometry that compensates for aberrations in the imaging system. In addition, the system employs a reference multiplexed, off-axis geometry for the determination of velocity directions with the cross-correlation technique, and a stereo camera geometry for the determination of the three velocity components. The combination of the imaging and reconstruction subsystems makes the analysis of volumetric PIV domains feasible.

N Hutchins - One of the best experts on this subject based on the ideXlab platform.

William Hambleton - One of the best experts on this subject based on the ideXlab platform.