Bulletin of the American Physical Society
75th Annual Meeting of the Division of Fluid Dynamics
Volume 67, Number 19
Sunday–Tuesday, November 20–22, 2022; Indiana Convention Center, Indianapolis, Indiana.
Session A11: Acoustics: General |
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Chair: Akihito Kiyama, Cornell; Brian Elbing, Oklahoma State University Room: 139 |
Sunday, November 20, 2022 8:00AM - 8:13AM |
A11.00001: Developing Acoustic Emission Techniques to Characterize Particle-Gas Flows Fria A Hossein The characterization of particles in solid-gas flows is of great importance in many industrial sectors such as nuclear energy and pharmaceuticals industries. Acoustic techniques can provide non-intrusively, multi-point measurements in non-transparent systems and can complement other techniques e.g., optical sensors, x-ray. In this work, acoustic emission (AE) techniques are applied to the study of gas-solid fluidized beds. The experimental setups, measurement method and signal processing methodology of the acoustic emission signal for obtaining particle size distribution, particle velocity in solid-gas fluidized bed are discussed. The experiments were conducted in a vertical tube with a 14 cm inner diameter, made of borosilicate glass, that contains 2 kg glass particles with density of 2500 kg/m3. The AE signals were measured experimentally for different particle sizes ranging from 100 μm to 1 mm. The measurement technique is based on the measurement of signal frequency, energy and root mean square (RMS) of the generated acoustic emission signal, to obtain particle velocity and particle size in the solid-gas flows. The results indicated that the acoustic emission features, root mean square RMS and energy of the AE are related to the change in gas superficial velocity and particle size, while the frequency of the generated AE signal is related to the particle size. A theoretical model is proposed for the generation of acoustic emission from the collision of particles with reactor wall. This study indicated that the AE features have great potential in the application of gas-solid flows. |
Sunday, November 20, 2022 8:13AM - 8:26AM |
A11.00002: Sound and cavity dynamics of hand clap Akihito Kiyama, Sunghwan Jung A hand clap is an everyday activity for either communication or entertainment purposes. However, to the best of our knowledge, there are only a few studies that discuss the underlying principles of fluid dynamics. Pioneering works (Repp ( J. Acoust. Soc. Am., 1987) and Fletcher (Acoustics Australia, 2013)) suggested that the hand shape configuration largely determines the frequency response of the associated sound. Specifically, the volume of a cavity formed between hands is one of the primary parameters. However, the experimental data have not been provided without any systematic investigation. In this study, we used silicone rubber to craft the simplified human hand model with relatively controlled geometry to discuss the contribution of cavity dynamics to the overall sound generation process. The major experimental parameters are the cavity size and clapping speed. In addition to these controlled parameters, the alignment of the impacting hands was found to be one of the important factors. A combination of high-speed imaging and acoustic sensing allowed us to discrete sound data into regimes and like them to the clapping motion. Furthermore, we would like to report the results of the forthcoming experiment involving human subjects, which is currently planned. |
Sunday, November 20, 2022 8:26AM - 8:39AM |
A11.00003: Strong microscopic capillary wave turbulence: Lévy flights and rogue waves Jeremy Orosco, William Connacher, Kha Nguyen, James Friend Tiny (O(10-6)μL) pools of water excited by very high frequency (O(106)Hz) ultrasonic vibrations at nanoscale (O(10-9)m) amplitudes exhibit visible turbulent capillary waves (O(10-2)m amplitudes and O(10-1)s periods) at the free interface. In these systems, there is a complete absence of any classically predicted instability mechanisms such as Faraday wave theory. Modern studies of these systems utilize modeling approaches confined by the weakly nonlinear constraint (\ie, weak wave turbulence). We present recently acquired measurements of microscopic capillary wave turbulence occurring at high levels of nonlinearity. In this regime, we show that the wave processes may be described as an alpha-stable process with varying distribution tails. The results demonstrate that increasing input power causes a commensurate increase in tail heaviness and leads to greater commonality of rogue events. Discussion of implications and future research directions is contextualized by the problem of controlled atomization. |
Sunday, November 20, 2022 8:39AM - 8:52AM |
A11.00004: A comparison of wind filters for deployable remote infrasound monitoring Christopher E Petrin, Brian R Elbing
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Sunday, November 20, 2022 8:52AM - 9:05AM |
A11.00005: Generalized Acoustic Helmholtz Equation and its Boundary Conditions in a Quasi 1-D Duct with Arbitrary Mean Properties and Mean Flow Sarma L Rani, Sattik Basu We derive the generalized Helmholtz equation |
Sunday, November 20, 2022 9:05AM - 9:18AM |
A11.00006: Acoustic Nonlinearities in a Quasi 1-D Duct with Arbitrary Mean Properties and Mean Flow Sarma L Rani, Swarnalatha Kathalagiri Vasantha Kumar, Sattik Basu Nonlinear temporal dynamics of acoustic oscillations in a quasi one-dimensional (1-D) duct are investigated using both numerical and analytical methods. The spatiotemporal nonlinear wave equation is derived for pressure oscillations in a quasi 1-D duct with axially varying cross-section and spatially inhomogeneous mean properties such as the velocity, temperature, density and pressure. Using the finite element method with quadratic interpolation functions, the linear Helmholtz equation is solved for the modal shapes and frequencies. With the modal shape as the weighting function, the standard Galerkin method is applied to transform the spatiotemporal wave equation into a second-order nonlinear ordinary differential equation (ODE) governing the time evolution of modal amplitudes. The limit-cycle amplitude and frequency of pressure oscillations are quantified analytically using the Lindstedt--Poincar\'{e} perturbation method. Furthermore, to capture the transient evolution to the limit cycle, the method of averaging is applied to the nonlinear temporal ODE for the modal amplitude. From the Lindstedt--Poincar\'{e} method, it is seen that a limit cycle exists when the linear damping coefficient $\mu$ in the nonlinear ODE is of the opposite sign as the quantity $S$ that is a function of the coefficients of the quadratic and cubic terms in the ODE. |
Sunday, November 20, 2022 9:18AM - 9:31AM |
A11.00007: Development of high altitude balloon based sensing of low frequency sounds from severe storms Taylor Swaim, Brian R Elbing, Jamey D Jacob, Emalee Hough, Zach Yap There is evidence that tornadoes emit sound at frequencies below human hearing, which is called infrasound. This has been detected from ground-based sensors, but the ability to detect at the ground is very sensitive to atmospheric conditions. Our team has helped pioneer the ability to record infrasound from high altitude balloons called heliotropes. Heliotropes are free-floating solar balloons that float within the lower stratosphere (~20 km) throughout the daytime. Use of balloons significantly mitigates the wind noise problem that is common for most infrasound measurements, but some relative motion will exist as the sensors are dragged below the balloon envelope. This talk will present details on the development of a mounting system to mitigate wind noise. In addition, details of heliotrope operations and flight performance will be discussed, including the planning required to intercept a severe storm. |
Sunday, November 20, 2022 9:31AM - 9:44AM |
A11.00008: Development and Deployment of an Infrasound Sensor System with Tornado Chasers Bryce B Lindsey, Brian R Elbing, Imraan Faruque Evidence suggests that during tornadogenesis and through the life of a tornado, acoustic waves at frequencies below human hearing (i.e. infrasound) are produced. To date, interpretation of these sounds has been hindered by the lack of observations. Thus, our team designed and built the Ground-based Local Infrasound Data Acquisition (GLINDA) system in 2019 to deploy with storm chasers. The current work is the development of version 2 of GLINDA (GLINDA 2.0) with the aim of reducing its footprint, improving automated operation stability, and reducing the cost to enable broader distribution of the sensor packages. This presentation will report on the system improvements and insights gained during development. In addition, preliminary data from a deployment of GLINDA 2.0 with storm chasers in April of 2022 will be shown, which includes recordings during an interception of an EF3 tornado on 29 April 2022 in Andover, KS. |
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