Bulletin of the American Physical Society
72nd Annual Meeting of the APS Division of Fluid Dynamics
Volume 64, Number 13
Saturday–Tuesday, November 23–26, 2019; Seattle, Washington
Session A26: Experimental Measurements: General |
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Room: 608 |
Saturday, November 23, 2019 3:00PM - 3:13PM |
A26.00001: Micro-PIV Evaluation of Lateral Flow Assays Emilie Newsham, Steve Wereley, Jacqueline Linnes Lateral flow assays (LFAs) are an increasingly common technology (e.g. pregnancy tests) but are limited in scope and sensitivity due to minimal understanding of their underlying fluidic properties. LFAs comprise porous paper membranes that transport liquid samples along a test strip through capillary action to dried reagents, where binding reactions produce a readable signal. Mathematical models informed by analytical evaluations have been created to optimize LFA development, but none use empirical microfluidic data to derive model parameters. Here, micro-PIV is used to evaluate liquid flow in LFAs. Videos of liquids carrying nanoparticles flowing through LFA membranes under different conditions are analyzed using micro-PIV. The porous membrane has different permeability to the liquid and nanoparticles which means the observed particle motion is not the same as the fluid motion. A scale factor between the visible macroscopic fluid front and microscopic particle velocity is derived. This novel microscopic evaluation method will inform intelligent models for more efficient development of LFAs. [Preview Abstract] |
Saturday, November 23, 2019 3:13PM - 3:26PM |
A26.00002: V3V Measurements on a Propeller in a Cavitation Water Channel Dan Troolin, Wing Lai Cavitation around ship propellers occurs due to low pressure regions where cavitation bubbles form and collapse potentially causing severe damage to propeller blade surfaces through unequal loading, vibration, and pitting. In order to avoid cavitation damage care must be taken in the design, selection and operation of the propeller blades. A study was conducted in the West Japan Fluid Engineering Laboratory Co., Ltd. closed return cavitation water channel with a test section of 500 × 500 × 2000 mm of the flow downstream of a five-bladed, powered aquatic propeller at a freestream velocity of 4.0 m/s. A V3VFlex volumetric measurement system with four 4 megapixel cameras was used in order to provide high-resolution instantaneous and phase-averaged volumetric measurements. The measurements reveal the presence of tip vortex structures, locations and interactions. Results of the propeller wake will be presented and examined. [Preview Abstract] |
Saturday, November 23, 2019 3:26PM - 3:39PM |
A26.00003: Gridded Analysis of Volumetric Particle Velocity Data Matt Stegmeir 2-Frame and time-resolved Volumetric Particle Tracking has become an increasingly valuable tool for 3-D flow characterization. Unstructured, randomly-distrubted data are typically produced by tracking individual particle locations either between 2 sequential image frames or by constructing longer Lagrangian particle position tracks to from highly time-resolved data. High-resolution datasets are typically interpolated onto an ordered grid in order to provide greater convenience in data presentation and to facilitate calculation of derived quantities. Interpolation schemes are compared for accuracy and resolution, and robustness to spurious data points. Improvements are proposed to provide for increased resilience against noise and spurious data points in experimental data sets. Results are compared to standard Gaussian-weighted interpolation. Single- realization and statistical results are presented from analysis of synthetic and experimental datasets. [Preview Abstract] |
Saturday, November 23, 2019 3:39PM - 3:52PM |
A26.00004: Droplet sizing of opaque liquid with integrated transmitting and receiving optical arrangement Wing T. Lai, Dan Troolin A number of industrial applications require the precise sizing of droplets. Some examples are spray drying in drug formation and ink jet printing for TV panels. The technique of ink jet printing for making TV panels requires the droplets emitting from the printer nozzles to be monodisperse and uniform for a long period of time. A typical printer head consists of multiple nozzles, from 256 to 1046. Every nozzle is designed to be producing the same droplet size of liquid over the period of time when the panel is being made. Hence it is important to be able to monitor all the nozzles regularly to ensure the uniform droplets are produced. If there is any size deviation of the droplets from the nozzles, the quality of the panel can be substantially degraded, making it non-useable. An integrated transmitting and receiving optical probe was designed specifically for the measurement of the droplets from all the nozzles in a sequential fashion such that every nozzles in the printer head can be characterized. The droplet result provides the feedback of any faulty nozzle behavior (one not giving the correct droplet size) and adjustment of the flow system can be made to get the nozzle working normal again. [Preview Abstract] |
Saturday, November 23, 2019 3:52PM - 4:05PM |
A26.00005: Development of a Flexible Four-Camera Volumetric PIV System for Tow Tank Applications Ruben Hortensius, Stamatios Pothos, Mark Cecconi Traditionally PIV experimentation for hydrodynamic, marine, and biological applications, have been carried out in water tunnel facilities, where the instrumentation is safely located outside of the facility. Due to practical constraints, this has often resulted in limited ability to conduct experiments at large scale or at high magnifications. To overcome this, submersible PIV systems have been developed, allowing for PIV experimentation in facilities such as towing tanks. These tow tank PIV systems, whether 2D/planar-PIV or 3D/stereo-PIV, are still regarded as very unique and highly specialized, in no small part due to the exceptionally distinctive facilities which house them. TSI has provided numerous PIV systems for underwater applications in the past, and in 2017 produced a specialized system capable of being used for 2D/planar measurements, 3D/stereoscopic measurements, and 3D3C volumetric measurements. Details of the capabilities of the new system are described, as well as insights gleaned from the design, manufacture, and installation of this one-of-a-kind system. Preliminary volumetric PIV results obtained with the system are shared and discussed. [Preview Abstract] |
Saturday, November 23, 2019 4:05PM - 4:18PM |
A26.00006: Volumetric 3D-3C (V3V) Particle Tracking Velocimetry measurement of turbulent twin jet Nimesh Virani, Vesselina Roussinova, Ram Balachandar Recently developed (by TSI, Inc., Shoreview, MN, USA) V3V- Volumetric three-direction, three-component (3D-3C) particle tracking velocimetry technique, is applied for understanding of inherently complex interaction between turbulent twin jets. Two jets are separated by a distance of approximately 2D, where D is the diameter of the jet and Reynolds number based on exit diameter of the pipe, for both jet is around 12000. Jets are released into a channel comprising of quiescent water and channel dimensions are such that, jets can remain free from any kind of boundary effects. The measurement volume of approximately 150\texttimes 100\texttimes 50 mm$^{\mathrm{3}}$ in X, Y and Z directions, which is equivalent to 63D\texttimes 42D\texttimes 21D in terms of pipe diameter, was investigated for mean and turbulence characteristics of problem under consideration. Particle tracking velocimetry (PTV) is applied to trace randomly spaced seeding particles between concurrently captured two frames of the same instant of flow field. PTV eliminates inherent bias present in the traditional FFT correlation based analysis of particle image velocimetry (PIV). Access to all three components of velocity enabled us to get insight of shear layer merging phenomena between two jets, which resulted into some interesting instantaneous flow structures. Time-averaged and turbulent characteristics of jets' interaction are analyzed using various statistical analysis tools and they reiterate the necessity of 3D examination. [Preview Abstract] |
Saturday, November 23, 2019 4:18PM - 4:31PM |
A26.00007: Experimental Characterization of Flow Induced by a Nanosecond Surface Discharge Lalit Rajendran, Bhavini Singh, Ravichandra Jagannath, George Schmidt, Pavlos Vlachos, Sally Bane Nanosecond surface Dielectric Barrier Discharges (ns-DBD) have generated growing interest as a means of high speed flow control. These discharges are characterized by electrical breakdown caused by high voltage, nanosecond pulses resulting in ultra-fast heating of the surrounding air. The rapid heat release leads to generation of a shock wave and complex flow characterized by coherent vorticity and a hot gas kernel near the electrode surface. Past applications of these discharges have yielded mixed results in flow control and the reasons for success/failure of these actuators are not well understood. This is because a fundamental understanding of the induced flow field and its relation to electrode geometry and energy deposited is not available. To address this limitation, we have performed high speed Particle Image Velocimetry (PIV) and Background Oriented Schlieren (BOS) measurements on the flow induced by a single nanosecond filamentary surface discharge under quiescent conditions. We measure the vorticity and density of the hot gas kernel and create a mechanistic model of the actuator induced flow. Such a model of the actuator performance can inform the choice and deployment of these devices for flow control applications. [Preview Abstract] |
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