MRI: Acquisition of a Digital Particle Image Velocimetry System for Studying Fluid Flow Around Organismal, Robotic and Marine Structures

University Of Rhode Island, Kingston RI

Investigators

Abstract

Funds will be used to purchase a digital particle image velocimetry (DPIV) system that will enable students and researchers to visualize and quantify fluid flow around robotic biological, and marine structures using high-resolution video recordings. DPIV is an experimental technique for quantitatively visualizing fluid flow. The fluid medium is seeded with neutrally buoyant, reflective particles that are illuminated by a sheet of laser light. Particle movement is recorded by a camera, oriented perpendicular to the laser sheet. Vector fields are calculated by evaluating the cross-correlation between groups of particles in successive images. The requested DPIV system consists of a low-speed high-resolution camera (up to 30 frames/s, 1648x1214 pixel resolution, 512 MB onboard memory, 14-bit digital output, 7.4x7.4 µm pixels, LaVision Imager Pro X2M with PCII Frame Grabber), one high-speed high-resolution camera (1000 f/s at full resolution, up to 60,000 f/s at reduced resolution, 12 bit digital output, 2GB onboard memory, 1024x1024 pixel resolution, 17x17µm pixels, LaVision HighSpeedStar 3 GigE), and a high repetition laser (30 mJ/pulse @527nm at 1 kHz repetition rate, with integrated chiller). Camera lenses include a: 50 mm F/1.8 lens, 50mm F/1.4 lens, variable magnification 12X zoom Navitar lens, and a close-up zoom lens with an adaptor for microscopic use. Optics include an adjustable lens with focal length between 300-2000 mm, one -10 mm, and one -20 mm focal length lens with anti-reflection coating. Particles are near neutrally buoyant, reflective, hollow glass particles at a density of 15 mg/l. A camera is synchronized to record simultaneously with the laser through a timing unit managed by a control computer. A separate computer system runs each of the camera systems (low- and high-speed) and each system is capable of controlling the laser (quad-core processor PC, 2 GB Ram, 250 GB hard drive, RW DVD, 19" monitor, software and camera interface, LaVision). DaVis v.7 software, consisting of processing routines for 2D PIV/PTV (Particle Tracking Velocimetry), is used for image acquisition, processing, and hardware control. DaVis software allows calculation of velocity vectors and derivatives of the flow field along with the visualization of streamlines, jets, vortices and other fluid structures. The kinematics of flow structures are derived by compiling the images over time using ProAnalyst software for digitizing and 2D structure design. Quantitative flow visualization performed in specific projects will include characterizing fluid flow around shark fins, analyzing advective effects on plankton swimming and distributions, calculating friction and drag forces on SONAR components, characterizing flow separation on underwater vehicles and unsteady renewable energy devices, and determining drag effects due to biofilm formation and biofouling onsurfaces submerged in marine environments. The quantitative characterization of fluid flows is of fundamental importance in both natural and engineered systems, where the motion of fluid affects the morphology, function and ecology of organisms and determines the forces exerted on marine structures. The requested system is designed to enable experiments ranging from microscopic to macroscopic length scales, in a range of fluid flow regimes and supports research in engineering, life sciences and oceanography. The DPIV system will enable research projects studying the flow around robotic, marine structures, sonar components and biological systems ranging from bacteria and plankton to sharks. An interdisciplinary team including biologists, engineers and oceanographers at URI, Providence College, and Roger Williams University proposed an exciting set of research projects that examine the role of fluid flow in (1) the fluid flow around shark fins, (2) fluid effects on propulsion and predator prey interactions of gelatinous zooplankton, (3) fluid effects on the ecology and distribution of planktonic organisms, (4) tribological studies of friction and drag on SONR components, 5) drag and energy loss due to microbial growth on surfaces submerged in marine environments, and (6) local flow detection for feedback control of underwater vehicles and renewable energy devices. Acquisition of the DPIV system provides critical capabilities that strengthen RI higher education institutions' competitiveness in research and education. The system will be used in undergraduate and graduate courses and both undergraduate and graduate students and postdoctoral researchers will be trained to use the DPIV system in their research. Students benefit from this hands-on learning approach that relies on integrating basic scientific disciplines with mathematical and analytical approaches in a practical and intuitive manner.