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Journal articles on the topic 'TBL Pressure Spectrum Model'

Author: Grafiati

Published: 6 September 2023

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1

Biplab Ranjan Adhikary, Ananya Majumdar, Atanu Sahu, and Partha Bhattacharya. "Sensitivity of TBL Wall-Pressure over the Flat Plate on Numerical Turbulence Model Parameter Variations." CFD Letters 15, no. 7 (2023): 148–74. http://dx.doi.org/10.37934/cfdl.15.7.148174.

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A two-fold sensitivity of the zero-pressure gradient (ZPG) turbulent boundary layer (TBL) wall-pressure spectrum to different RANS model parameters is investigated for a flat plate case, which is a close approximation to the aircraft fuselage or wing. The alteration in the mean square pressure fluctuations due choice of semi-empirical pressure model and the choice of computational model parameters like solver, near wall grid clustering, measuring location, and flow velocity are separately studied. The underlying effect of different TBL parameters in the said sensitivity has been studied while

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2

Shao, Jianwang, Jinmeng Yang, Xian Wu, Cheng Wang, and Guoming Deng. "Study on Radiated Noise of a Panel under Fluctuating Surface Pressure Due to an Idealized Side Mirror." Applied Sciences 10, no. 3 (2020): 994. http://dx.doi.org/10.3390/app10030994.

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As traditional automobiles develop towards new energy vehicles, the noise, vibration and harshness (NVH) performance of automobiles is facing new challenges. Without the cover of the traditional engine noise and inlet and exhaust noise, the high-speed wind noise becomes more prominent. Thus, research on the calculation method of vehicle interior noise in high-speed driving condition is needed. However, vehicle body structure is complex, and the external excitation components are complicated. In order to analyze the method of predicting the vehicle interior noise at high speed, an idealized sid

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3

Leehey, P. "Structural Excitation by a Turbulent Boundary Layer: An Overview." Journal of Vibration and Acoustics 110, no. 2 (1988): 220–25. http://dx.doi.org/10.1115/1.3269502.

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Thirty years of theoretical and experimental research have yet to resolve a number of questions regarding the vibratory response of, and acoustic radiation from, a structure excited by a turbulent boundary layer (TBL). The most important questions are: (a) Can the TBL be characterized as a Thevenin source—particularly when vibratory power flow into the structure is maximized at hydrodynamic coincidence? Alternatively, at what level does structural vibration fundamentally change the character of the TBL? (b) Is the low wave number portion of the wall pressure spectrum of dominant importance in

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4

Rao, V. Bhujanga, P. V. S. Ganesh Kumar, and P. K. Gupta. "Viscous Effects on Turbulent Boundary-Layer Noise of Ship's Sonar Dome in a Water Tunnel." Journal of Ship Research 35, no. 04 (1991): 331–38. http://dx.doi.org/10.5957/jsr.1991.35.4.331.

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Turbulent boundary-layer (TBL) wall pressure fluctuations of a body measured in a water tunnel need correction to obtain unbounded free-field values. Besides blockage effects in a tunnel which are easily accounted for, viscous effects on TBL noise are to be evaluated to quantify this correction. An analytical method using suitable wave vector spectrum modeling to estimate the correction needed due to viscous effects is presented. A sonar dome body is considered as a typical example.

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5

Huang, Chunlong, Hui Li, and Nansong Li. "Flow Noise Spectrum Analysis for Vertical Line Array During Descent in Deep Water." Journal of Theoretical and Computational Acoustics 28, no. 04 (2020): 2050022. http://dx.doi.org/10.1142/s259172852050022x.

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Reliable acoustic path (RAP) is a direct path used for sound propagation between a shallow source and a deep receiver in deep water. The RAP environment can provide a high signal-to-noise ratio (SNR) environment for source localization, so it has been widely studied for underwater passive detection. Active detection can be used for source localization during the descent of a vertical line array (VLA). However, the flow noise originating from the pressure fluctuations in the turbulent boundary layer (TBL) during the descent degrades the detection performance of the VLA. This paper presents a ca

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6

Shi, Beiji, Zhaoyue Xu, and Shizhao Wang. "A non-equilibrium slip wall model for large-eddy simulation with an immersed boundary method." AIP Advances 12, no. 9 (2022): 095014. http://dx.doi.org/10.1063/5.0101010.

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A non-equilibrium wall model for large-eddy simulation with the immersed boundary (IB) method is proposed to reduce the required number of grid points in simulating wall-bounded turbulence. The proposed wall model is presented as an appropriate slip velocity on the wall. The slip velocity is constructed by integrating the simplified turbulent boundary layer (TBL) equation along the wall-normal direction, which enhances the integral momentum balance near the wall on a coarse grid. The effect of pressure gradient on the near wall flow is taken into account by retaining the pressure gradient term

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7

Guillon, Corentin, Emmanuel Redon, and Laurent Maxit. "Vibroacoustic simulations with non-homogeneous TBL excitations: Synthesis of wall pressure fields with the Continuously-varying Uncorrelated Wall Plane Waves approach." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, no. 7 (2023): 544–51. http://dx.doi.org/10.3397/in_2022_0075.

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A numerical method is presented to predict the vibro-acoustic response of a vibrating structure excited by a spatially inhomogeneous turbulent boundary layer(TBL). It is based on the synthesis of different realizations of the random pressure fluctuations that can be introduced as loadings of a vibro-acoustic model (such as a finite element model). To generate the pressures of the non-homogeneous turbulent boundary layer, the Uncorrelated Wall Plane Wave(UWPW) approach used so far for homogeneous TBL is extended. On a first step, this extension is based on a decomposition of the excited surface

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8

Shepherd, Micah. "Excitation of structures by partially correlated pressures: A review of diffuse acoustic field and turbulent boundary layer models." Journal of the Acoustical Society of America 153, no. 3_supplement (2023): A75. http://dx.doi.org/10.1121/10.0018211.

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Structures are sometimes excited by pressure distributions which exhibit complex spatial correlation. This differs from common acoustic excitations since the pressure at one location is only partially correlated with the pressure at another location due to inherent spatial randomness within the forcing function. Two forcing functions which exhibit partially-correlated pressures are the diffuse acoustic field (DAF) and turbulent boundary layer (TBL) flow. A basic model for representing the spatial correlation for these two forcing functions will be reviewed in both the spatial and wavenumber do

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9

OWEIS, GHANEM F., ERIC S. WINKEL, JAMES M. CUTBRITH, STEVEN L. CECCIO, MARC PERLIN, and DAVID R. DOWLING. "The mean velocity profile of a smooth-flat-plate turbulent boundary layer at high Reynolds number." Journal of Fluid Mechanics 665 (December 6, 2010): 357–81. http://dx.doi.org/10.1017/s0022112010003952.

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Smooth flat-plate turbulent boundary layers (TBLs) have been studied for nearly a century. However, there is a relative dearth of measurements at Reynolds numbers typical of full-scale marine and aerospace transportation systems (Reθ = Ueθ/ν > 105, where Ue = free-stream speed, θ = TBL momentum thickness and ν = kinematic viscosity). This paper presents new experimental results for the TBL that forms on a smooth flat plate at nominal Reθ values of 0.5 × 105, 1.0 × 105 and 1.5 × 105. Nominal boundary layer thicknesses (δ) were 80–90mm, and Karman numbers (δ+) were 17000, 32000 and 47000, res

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10

Goody, Michael. "An empirical model for the frequency spectrum of surface pressure fluctuations." Journal of the Acoustical Society of America 111, no. 5 (2002): 2379. http://dx.doi.org/10.1121/1.4778064.

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11

Lysak, Peter D. "Modeling the Wall Pressure Spectrum in Turbulent Pipe Flows." Journal of Fluids Engineering 128, no. 2 (2005): 216–22. http://dx.doi.org/10.1115/1.2170125.

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An important source of vibration and noise in piping systems is the fluctuating wall pressure produced by the turbulent boundary layer. One approach to calculating the wall pressure fluctuations is to use a stochastic model based on the Poisson pressure equation. If the model is developed in the wave-number domain, the solution to the wave-number-frequency spectrum can be expressed as an integral of the turbulent sources over the boundary layer thickness. Models based on this formulation have been reported in the literature which show good agreement with measured pressure spectra, but they hav

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12

Lam, N. T. K., Priyan Mendis, and Tuan Ngo. "Response Spectrum Solutions for Blast Loading." Electronic Journal of Structural Engineering 4 (January 1, 2004): 28–44. http://dx.doi.org/10.56748/ejse.439.

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Existing knowledge on the modelling of blast pressure have been further developed in this paper for engineering applications. Parametric studies involving time-history analyses of simple cantilevered wall models have been undertaken based on pre-defined pressure functions to study basic trends. The "corner period" of the velocity response spectrum was found to be the key controlling parameter in response behaviour modelling of the walls. An important contribution from this study is the identification of the directrelationship between the corner period and the "clearing time" for the blast. A s

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13

Brown, Michael G. "A directional spectrum evolution model for ship noise." Journal of the Acoustical Society of America 153, no. 6 (2023): 3469. http://dx.doi.org/10.1121/10.0019851.

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A radiation transport equation that describes the spatiotemporal evolution of the directional spectrum of underwater acoustic noise is presented and applied to ship noise. A ray-based algorithm is used to solve the transport equation and numerically simulate the evolution of the directional noise spectrum produced by a passing ship. The model described accounts for the transient and highly episodic nature of shipping noise, the strong anisotropy of the radiated shipping noise, the directional dependence of the resulting acoustic field, and the critical angle dependence of bottom-reflected ener

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14

Beqiri, Erta, Marek Czosnyka, Afroditi D. Lalou, et al. "Influence of mild-moderate hypocapnia on intracranial pressure slow waves activity in TBI." Acta Neurochirurgica 162, no. 2 (2019): 345–56. http://dx.doi.org/10.1007/s00701-019-04118-6.

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Abstract Background In traumatic brain injury (TBI) the patterns of intracranial pressure (ICP) waveforms may reflect pathological processes that ultimately lead to unfavorable outcome. In particular, ICP slow waves (sw) (0.005–0.05 Hz) magnitude and complexity have been shown to have positive association with favorable outcome. Mild-moderate hypocapnia is currently used for short periods to treat critical elevations in ICP. Our goals were to assess changes in the ICP sw activity occurring following sudden onset of mild-moderate hypocapnia and to examine the relationship between changes in ICP

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15

Xu, Qian, and Zhong-Qi Wang. "Model for Calculating Seismic Wave Spectrum Excited by Explosive Source." Shock and Vibration 2021 (June 3, 2021): 1–15. http://dx.doi.org/10.1155/2021/6544453.

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To reveal the characteristics and laws of the seismic wavefield amplitude-frequency excited by explosive source, the method for computing the seismic wave spectrum excited by explosive was studied in this paper. The model for calculating the seismic wave spectrum excited by explosive source was acquired by taking the seismic source model of spherical cavity as the basis. The results of using this model show that the main frequency and the bandwidth of the seismic waves caused by the explosion are influenced by the initial detonation pressure, the adiabatic expansion of the explosive, and the g

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16

Kato, Hiroharu, Akihisa Konno, Masatsugu Maeda, and Hajime Yamaguchi. "Possibility of Quantitative Prediction of Cavitation Erosion Without Model Test." Journal of Fluids Engineering 118, no. 3 (1996): 582–88. http://dx.doi.org/10.1115/1.2817798.

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A scenario for quantitative prediction of cavitation erosion was proposed. The key value is the impact force/pressure spectrum on a solid surface caused by cavitation bubble collapse. As the first step of prediction, the authors constructed the scenario from an estimation of the cavity generation rate to the prediction of impact force spectrum, including the estimations of collapsing cavity number and impact pressure. The prediction was compared with measurements of impact force spectra on a partially cavitating hydrofoil. A good quantitative agreement was obtained between the prediction and t

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17

Rocha, Joana, Afzal Suleman, and Fernando Lau. "Prediction of Turbulent Boundary Layer Induced Noise in the Cabin of a BWB Aircraft." Shock and Vibration 19, no. 4 (2012): 693–705. http://dx.doi.org/10.1155/2012/153204.

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This paper discusses the development of analytical models for the prediction of aircraft cabin noise induced by the external turbulent boundary layer (TBL). While, in previous works, the contribution of an individual panel to the cabin interior noise was considered, here, the simultaneous contribution of multiple flow-excited panels is analyzed. Analytical predictions are presented for the interior sound pressure level (SPL) at different locations inside the cabin of a Blended Wing Body (BWB) aircraft, for the frequency range 0–1000 Hz. The results show that the number of vibrating panels sign

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18

Kamruzzaman, M., D. Bekiropoulos, Th Lutz, W. Würz, and E. Krämer. "A Semi-Empirical Surface Pressure Spectrum Model for Airfoil Trailing-Edge Noise Prediction." International Journal of Aeroacoustics 14, no. 5-6 (2015): 833–82. http://dx.doi.org/10.1260/1475-472x.14.5-6.833.

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19

Liodakis, I. "Toy model for the acceleration of blazar jets." Astronomy & Astrophysics 616 (August 2018): A93. http://dx.doi.org/10.1051/0004-6361/201832766.

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Context. Understanding the acceleration mechanism of astrophysical jets has been a cumbersome endeavor from both the theoretical and observational perspective. Although several breakthroughs have been achieved in recent years, on all sides, we are still missing a comprehensive model for the acceleration of astrophysical jets. Aims. In this work we attempt to construct a simple toy model that can account for several observational and theoretical results and allow us to probe different aspects of blazar jets usually inaccessible to observations. Methods. We used the toy model and Lorentz factor

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20

Lee, Yu-Tai, William K. Blake, and Theodore M. Farabee. "Modeling of Wall Pressure Fluctuations Based on Time Mean Flow Field." Journal of Fluids Engineering 127, no. 2 (2004): 233–40. http://dx.doi.org/10.1115/1.1881698.

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Time-mean flow fields and turbulent flow characteristics obtained from solving the Reynolds averaged Navier-Stokes equations with a k‐ε turbulence model are used to predict the frequency spectrum of wall pressure fluctuations. The vertical turbulent velocity is represented by the turbulent kinetic energy contained in the local flow. An anisotropic distribution of the turbulent kinetic energy is implemented based on an equilibrium turbulent shear flow, which assumes flow with a zero streamwise pressure gradient. The spectral correlation model for predicting the wall pressure fluctuation is obta

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21

Luesutthiviboon, Salil, Daniele Ragni, Francesco Avallone, and Mirjam Snellen. "An alternative permeable topology design space for trailing-edge noise attenuation." International Journal of Aeroacoustics 20, no. 3-4 (2021): 221–53. http://dx.doi.org/10.1177/1475472x211003295.

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This study focuses upon a new permeable topology design concept as an alternative to porous metal foams, for turbulent boundary layer trailing-edge (TBL-TE) noise attenuation. The present permeable topology has unconventional characteristics with respect to the metal foams: a combination of low flow resistivity r and high form drag coefficient C. The unconventional characteristics are realized by a Kevlar-covered 3D-printed perforated structure. An experimental study featuring a NACA 0018 airfoil model with a Kevlar-covered 3D-printed TE insert at chord-based Reynolds numbers up to [Formula: s

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22

Slama, Myriam, Cédric Leblond, and Pierre Sagaut. "A Kriging-based elliptic extended anisotropic model for the turbulent boundary layer wall pressure spectrum." Journal of Fluid Mechanics 840 (February 6, 2018): 25–55. http://dx.doi.org/10.1017/jfm.2017.810.

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The present study addresses the computation of the wall pressure spectrum for a turbulent boundary layer flow without pressure gradient, at high Reynolds numbers, using a new model, the Kriging-based elliptic extended anisotropic model (KEEAM). A space–time solution to the Poisson equation for the wall pressure fluctuations is used. Both the turbulence–turbulence and turbulence–mean shear interactions are taken into account. It involves the mean velocity field and space–time velocity correlations which are modelled using Reynolds stresses and velocity correlation coefficients. We propose a new

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23

Smol’yakov, A. V. "A new model for the cross spectrum and wavenumber-frequency spectrum of turbulent pressure fluctuations in a boundary layer." Acoustical Physics 52, no. 3 (2006): 331–37. http://dx.doi.org/10.1134/s1063771006030146.

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24

Mead, A. J., T. Tröster, C. Heymans, L. Van Waerbeke, and I. G. McCarthy. "A hydrodynamical halo model for weak-lensing cross correlations." Astronomy & Astrophysics 641 (September 2020): A130. http://dx.doi.org/10.1051/0004-6361/202038308.

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On the scale of galactic haloes, the distribution of matter in the cosmos is affected by energetic, non-gravitational processes, the so-called baryonic feedback. A lack of knowledge about the details of how feedback processes redistribute matter is a source of uncertainty for weak-lensing surveys, which accurately probe the clustering of matter in the Universe over a wide range of scales. We developed a cosmology-dependent model for the matter distribution that simultaneously accounts for the clustering of dark matter, gas, and stars. We informed our model by comparing it to power spectra meas

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25

Dadhich, Yogesh, Nazek Alessa, Reema Jain, Abdul Razak Kaladgi, Karuppusamy Loganathan, and V. Radhika Devi. "Thermal Onsets of Viscous Dissipation for Radiative Mixed Convective Flow of Jeffery Nanofluid across a Wedge." Symmetry 15, no. 2 (2023): 385. http://dx.doi.org/10.3390/sym15020385.

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The current analysis discusses Jeffery nanofluid’s thermally radiative flow with convection over a stretching wedge. It takes into account the Brownian movement and thermophoresis of the Buongiorno nanofluid model. The guiding partial differential equations (PDEs) are modified by introducing the symmetry variables, leading to non-dimensional ordinary differential equations (ODEs). To solve the generated ODEs, the MATLAB function bvp4c is implemented. Examined are the impacts of different flow variables on the rate of transmission of heat transfer (HT), temperature, mass, velocity, and nanopart

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26

Batrakov, Andrei. "Experimental and numerical simulation of the wall-pressure fluctuation on the isolated helicopter fuselage." EPJ Web of Conferences 269 (2022): 01002. http://dx.doi.org/10.1051/epjconf/202226901002.

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This work is devoted to wall-pressure fluctuation analysis. The object of investigation was an isolated helicopter fuselage. Investigation was carried out by experimental and numerical methods. Numerical simulation was based on RANS and DES approaches. The experiment was carried out in a lowspeed wind tunnel with an open test section. Wall-pressure fluctuation was measurement by high-frequency pressure probes ENDEVCO 8510B-2. The experimental results were compared with both DES data and results by the semi-empirical model based on the RANS simulation. It was shown that DES modelling provides a

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27

Ou, Li Jian, Feng Hong Wang, and Wei Zhang. "Marine Ducted Propeller Blade Fracture Fault Diagnosis Technology Based on CFD." Applied Mechanics and Materials 488-489 (January 2014): 1219–23. http://dx.doi.org/10.4028/www.scientific.net/amm.488-489.1219.

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The numerical model of the unsteady flow field of ducted propellers is based on CFD (computational fluid dynamics). By applying the numerical model, the unsteady flow field of the ducted propeller with the fracture in different positions of a certain blade is simulated and its unsteady hydrodynamic performance is numerically analyzed. By extracting the fluctuating pressure data of the duct inner wall monitoring points,the fluctuating pressure-time oscillogram of ducted propellers is obtained, and then the spectrum is obtained by FFT transformation of the oscillogram. A blade fracture fault dia

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28

Rao, V. Bhujanga. "Selection of a Suitable Wall Pressure Spectrum Model for Estimating Flow-Induced Noise in Sonar Applications." Shock and Vibration 2, no. 5 (1995): 403–12. http://dx.doi.org/10.1155/1995/720535.

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Flow-induced structural noise of a sonar dome in which the sonar transducer is housed, constitutes a major source of self-noise above a certain speed of the vessel. Excitation of the sonar dome structure by random pressure fluctuations in turbulent boundary layer flow leads to acoustic radiation into the interior of the dome. This acoustic radiation is termed flow-induced structural noise. Such noise contributes significantly to sonar self-noise of submerged vessels cruising at high speed and plays an important role in surface ships, torpedos, and towed sonars as well. Various turbulent bounda

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29

Fu, Liufang, Peng Li, Xinhua Zhang, Shuqing Ma, and Chengzhi Gao. "Vector Ocean Ambient Noise Spectrum Simulation Based on Parabolic Equation Model in Shallow Water." Journal of Computational Acoustics 25, no. 02 (2017): 1750034. http://dx.doi.org/10.1142/s0218396x17500345.

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Ocean ambient noise spectrum is one of the most important characteristics of ambient noise. An ocean vector ambient noise field model was built up based on parabolic equation in this paper. Then the spectra of sound pressure, horizontal particle velocity and vertical particle velocity were calculated applying the model considering noise sources well distributed on the surface with typical summer sound speed profile in South China Sea. The simulation results showed that spectra of sound pressure, horizontal particle velocity and vertical particle velocity were obviously not varied with depth. T

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30

Tamisier, R., J. L. Pepin, B. Wuyam, R. Smith, J. Argod, and P. Levy. "Characterization of pharyngeal resistance during sleep in a spectrum of sleep-disordered breathing." Journal of Applied Physiology 89, no. 1 (2000): 120–30. http://dx.doi.org/10.1152/jappl.2000.89.1.120.

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Aims of the study were 1) to compare Hudgel's hyperbolic with Rohrer's polynomial model in describing the pressure-flow relationship, 2) to use this pressure-flow relationship to describe these resistances and to evaluate the effects of sleep stages on pharyngeal resistances, and 3) to compare these resistances to the pressure-to-flow ratio (ΔP/V˙). We studied 12 patients: three with upper airway resistance syndrome (UARS), four with obstructive sleep hypopnea syndrome (OSHS), three with obstructive sleep apnea syndrome (OSAS), and two with simple snoring (SS). Transpharyngeal pressures were c

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31

Grasso, G., P. Jaiswal, H. Wu, S. Moreau, and M. Roger. "Analytical models of the wall-pressure spectrum under a turbulent boundary layer with adverse pressure gradient." Journal of Fluid Mechanics 877 (September 2, 2019): 1007–62. http://dx.doi.org/10.1017/jfm.2019.616.

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This paper presents a comprehensive analytical approach to the modelling of wall-pressure fluctuations under a turbulent boundary layer, unifying and expanding the analytical models that have been proposed over many decades. The Poisson equation governing pressure fluctuations is Fourier transformed in the wavenumber domain to obtain a modified Helmholtz equation, which is solved with a Green’s function technique. The source term of the differential equations is composed of turbulence–mean shear and turbulence–turbulence interaction terms, which are modelled separately within the hypothesis of

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32

Stosiak, Michał, Mykola Karpenko, Adam Deptuła, et al. "Research of Vibration Effects on a Hydraulic Valve in the Pressure Pulsation Spectrum Analysis." Journal of Marine Science and Engineering 11, no. 2 (2023): 301. http://dx.doi.org/10.3390/jmse11020301.

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This paper identifies mechanical vibrations occurring in the operating environment of hydraulic systems used in marine engineering. Particular attention was paid to the influence of periodic vibrations on changes in the amplitude-frequency spectrum in a marine hydraulic system. For the case of analysing the effect of vibration on changes in the pressure pulsation spectrum with a proportional directional valve, a modified mathematical model was used. Experimental results were presented and compared with the results obtained from the mathematical model. A way of limiting the transmission of vibr

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Burkhoff, D., J. Alexander, and J. Schipke. "Assessment of Windkessel as a model of aortic input impedance." American Journal of Physiology-Heart and Circulatory Physiology 255, no. 4 (1988): H742—H753. http://dx.doi.org/10.1152/ajpheart.1988.255.4.h742.

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To facilitate the analysis of aortic-ventricular coupling, simplified models of aortic input properties have been developed, such as the three-element Windkessel. Even though the impedance spectrum of the Windkessel reproduces the gross features of the real aortic input impedance, it fails to reproduce many of its details. In the present study we assessed the physiological significance of the differences between real and Windkessel impedance. We measured aortic input impedance spectra from five anesthetized open-chest dogs under a wide range of conditions. For each experimentally determined sp

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34

Grenner, J. "Significance of a notch in the otoacoustic emission stimulus spectrum." Journal of Laryngology & Otology 126, no. 9 (2012): 897–901. http://dx.doi.org/10.1017/s0022215112001533.

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AbstractObjective:To explain a clinical observation: a notch in the stimulus spectrum during transient evoked otoacoustic emission measurement in ears with secretory otitis media.Methods:The effects of tympanic under-pressure were investigated using a pressure chamber. A model of the ear canal was also studied.Results:Tympanic membrane reflectance increased as a consequence of increased stiffness, causing a notch in the stimulus spectrum. In an adult, the notch could be clearly distinguished at an under-pressure of approximately −185 daPa. The sound frequency of the notch corresponded to a wav

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35

Josserand, M. A., and G. C. Lauchle. "Modeling the Wavevector-Frequency Spectrum of Boundary-Layer Wall Pressure During Transition on a Flat Plate." Journal of Vibration and Acoustics 112, no. 4 (1990): 523–34. http://dx.doi.org/10.1115/1.2930138.

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A spectral model for the wall-pressure fluctuations induced on a zero pressure gradient, flat, rigid surface by a transitioning boundary layer at low Mach number is developed in this paper. The central assumption used in this modeling is that the space-time statistics associated with the formation, convection, and interaction of turbulent spots in a naturally occurring boundary-layer transition are independent of the space-time statistics of the wall-pressure fluctuations that are induced by the turbulence in the individual spots. Space-time correlations for the spots were determined experimen

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Layton, Anita T., Leon C. Moore, and Harold E. Layton. "Multistability in tubuloglomerular feedback and spectral complexity in spontaneously hypertensive rats." American Journal of Physiology-Renal Physiology 291, no. 1 (2006): F79—F97. http://dx.doi.org/10.1152/ajprenal.00048.2005.

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Single-nephron proximal tubule pressure in spontaneously hypertensive rats (SHR) can exhibit highly irregular oscillations similar to deterministic chaos. We used a mathematical model of tubuloglomerular feedback (TGF) to investigate potential sources of the irregular oscillations and the corresponding complex power spectra in SHR. A bifurcation analysis of the TGF model equations, for nonzero thick ascending limb (TAL) NaCl permeability, was performed by finding roots of the characteristic equation, and numerical simulations of model solutions were conducted to assist in the interpretation of

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37

Wang, Yue, Wanlong Ren, Gang Liu, Jin Liu, Juan Xu та Zongrui Hao. "The Pressure Pulsation and Spectrum Analysis of Ducted Propeller Based on SST k-ω model". Journal of Physics: Conference Series 1300 (серпень 2019): 012080. http://dx.doi.org/10.1088/1742-6596/1300/1/012080.

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Yan, Fuyong, De-Hua Han, and Xue-Lian Chen. "Pore Aspect Ratio Spectrum Inversion from Ultrasonic Measurements and Its Application." Journal of Computational Acoustics 23, no. 04 (2015): 1540009. http://dx.doi.org/10.1142/s0218396x15400093.

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We have conducted simultaneous ultrasonic velocity and pore volume change measurements on a carbonate rock sample. By including of pressure dependent porosity data, we have improved Cheng’s pore aspect ratio spectrum inversion methodology and made the inverted pore aspect ratio spectrum more realistic. Tang’s unified velocity dispersion and attenuation model is modified and extended to poroelastic media with complex pore structure under undrained condition. Using improved pore aspect ratio spectra inversion methodology and modified Tang’s model, we have explored the potential application of po

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Thomson, Nicholas, and Joana Rocha. "Comparison of Semi-Empirical Single Point Wall Pressure Spectrum Models with Experimental Data." Fluids 6, no. 8 (2021): 270. http://dx.doi.org/10.3390/fluids6080270.

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This study presents an evaluation of semi-empirical single-point wall pressure spectrum models by comparing model predictions with wind tunnel and flight test data. The mean squared error was used to compare the power spectral density of the wall pressure fluctuations predicted by semi-empirical models with a large amount of experimental data. Results show that the models proposed by Goody and Smol’yakov have the lowest mean squared error when predicting the power spectral density for wind tunnel experiments and the Rackl and Weston model has the lowest mean squared error when predicting the p

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Xie, Yingchun, Yucheng Xiao, Xuyan Liu, Guijie Liu, Weixiong Jiang, and Jin Qin. "Time-Frequency Distribution Map-Based Convolutional Neural Network (CNN) Model for Underwater Pipeline Leakage Detection Using Acoustic Signals." Sensors 20, no. 18 (2020): 5040. http://dx.doi.org/10.3390/s20185040.

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Detection technology of underwater pipeline leakage plays an important role in the subsea production system. In this paper, a new method based on the acoustic leak signal collected by a hydrophone is proposed to detect pipeline leakage in the subsea production system. Through the pipeline leakage test, it is found that the radiation noise is a continuous spectrum of the medium and high-frequency noise. Both the increase in pipe pressure and the diameter of the leak hole will narrow the spectral structure and shift the spectrum center towards the low frequencies. Under the same condition, the p

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Lee, Shouyan, and Geert W. Schmid-Scho¨nbein. "Biomechanical Model for the Myogenic Response in the Microcirculation: Part I—Formulation and Initial Testing." Journal of Biomechanical Engineering 118, no. 2 (1996): 145–51. http://dx.doi.org/10.1115/1.2795952.

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The pressure dependent or myogenic contraction of arterioles is one of the most fundamental control mechanisms of microvascular perfusion. While many experimental observations have been obtained on the myogenic response, no generally accepted biomechanical model has been formulated. A novel biomechanical theory is proposed based on two fundamental assumptions: the arteriolar wall exhibits viscoelastic properties before and during myogenic contractions, and the contraction is achieved by a pressure dependent change of reference length. The formulation of the model and its application to differe

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Zuckerman, B. D., H. F. Weisman, and F. C. Yin. "Arterial hemodynamics in a rabbit model of atherosclerosis." American Journal of Physiology-Heart and Circulatory Physiology 257, no. 3 (1989): H891—H897. http://dx.doi.org/10.1152/ajpheart.1989.257.3.h891.

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Although atherosclerosis significantly alters the structural characteristics of the arterial tree, its effect on arterial impedance, which is a means of quantifying the functional characteristics of the arterial system, has not been characterized. To assess how one type of atherosclerosis affects impedance, we studied arterial impedance in New Zealand White rabbits after 11 wk on a 2% cholesterol diet. From open-chest aortic pressures and flows, impedance data were obtained from spectral analysis of randomly paced and Fourier analysis of nonpaced beats. Compliance was calculated from the low-f

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Zhang, Jian Guo, and Hui Min Zhuang. "Wind Tunnel Test of Symmetrical Twin-Tower Tall Building Model." Advanced Materials Research 919-921 (April 2014): 518–22. http://dx.doi.org/10.4028/www.scientific.net/amr.919-921.518.

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In this paper, taking symmetrical twin-tower tall building model as an example, a wind tunnel test with simultaneous surface pressure measurement, in 7 wind directions, was carried out. Integration of the surface pressures leads to base moment coefficient, of which the amplitude and frequency-domain characteristics were analyzed and compared with those of single tall building model. The result shows that mean value and root mean square of the interfering tower, in all wind directions, are basically the same as those of single tower, while in 0o wind direction, they differ greatly; mean value a

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Ethier, L., N. E. Massa, A. Béliveau, and C. Carlone. "The Raman spectrum of Cs2SeO4 crystals." Canadian Journal of Physics 67, no. 7 (1989): 657–63. http://dx.doi.org/10.1139/p89-120.

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The Raman spectrum of Cs2SeO4 crystals has been obtained at T = 20 K. We have observed 23 of the 24 external modes predicted by a model with four formula units per unit cell. A comparison of the internal mode frequencies with those of the solution spectrum shows that the charge on the SeO4 tetrahedron is, in the crystal phase, less than two electrons. We have obtained the temperature dependence of the Raman spectrum from 20 to 650 K. For the internal modes only, we have observed the pressure dependence up to 25 kbars, and we have evaluated the volume dilatation and the interaction contribution

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Galindo, José, Francisco José Arnau, Luis Miguel García-Cuevas, and Pablo Soler. "Experimental validation of a quasi-two-dimensional radial turbine model." International Journal of Engine Research 21, no. 6 (2018): 915–26. http://dx.doi.org/10.1177/1468087418788502.

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This article presents the experimental validation of a quasi-two-dimensional radial turbine model able to be used in turbocharged reciprocating internal combustion engine simulations. A passenger car variable-geometry turbine has been tested under steady and pulsating flow conditions, instrumented with multiple pressure probes, temperature sensors and mass flow sensors. Using the data obtained, a pressure decomposition has been performed. The pressure at the turbine inlet and outlet has been split into forward and backward travelling waves, employing the reflected and transmitted waves to veri

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Hao, Jin Feng, Jian Hua Gao, Yang Liu, and Gui De Liu. "Spectrum Analysis of Isolated Vertical Seismic Response Storage Tanks." Applied Mechanics and Materials 166-169 (May 2012): 2270–74. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.2270.

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Aiming at the problem of seismic response of the base isolation tanks, make the tanks simplify the mechanical model of three particles, considering the quality of continuous liquid that is in the tanks equivalent to convection quality, pulse quality and rigid quality and introducing isolation stiffness. According to the stiffness of each particle and quality calculate natural vibration period, making sure the power amplification coefficient, and analysis on the response spectrum of isolation vertical seismic response storage tanks. The results show that the response spectrum method calculating

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LI, CHENXI, JINGYING JIANG, and KEXIN XU. "THE VARIATIONS OF WATER IN HUMAN TISSUE UNDER CERTAIN COMPRESSION: STUDIED WITH DIFFUSE REFLECTANCE SPECTROSCOPY." Journal of Innovative Optical Health Sciences 06, no. 01 (2013): 1350005. http://dx.doi.org/10.1142/s1793545813500053.

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The reflectance spectrum has been widely adopted to extract diagnosis information of human tissue because it possesses the advantages of noninvasive and rapidity. The external pressure brought by fiber optic probe may influence the accuracy of measurement. In this paper, a systematic study is focused on the effects of probe pressure on intrinsic changes of water and scattering particles in tissue. According to the biphasic nonlinear mixture model, the pressure modulated reflectance spectrum of both in vitro and in vivo tissue is measured and processed with second-derivation. The results indica

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Chase, D. M. "The character of the turbulent wall pressure spectrum at subconvective wavenumbers and a suggested comprehensive model." Journal of Sound and Vibration 112, no. 1 (1987): 125–47. http://dx.doi.org/10.1016/s0022-460x(87)80098-6.

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Gisby, J. A., and S. H. Walmsley. "A model of the effects of pressure on the near ultraviolet absorption spectrum of crystalline naphthalene." Chemical Physics Letters 135, no. 3 (1987): 275–78. http://dx.doi.org/10.1016/0009-2614(87)85155-2.

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Segovia-Chaves, Francis, Herbert Vinck-Posada, and Edgar A. Gómez. "Transmittance in a dispersive quasiperiodic photonic crystal." International Journal of Modern Physics B 35, no. 04 (2021): 2150061. http://dx.doi.org/10.1142/s0217979221500612.

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In this work, transmittance spectrum for a quasiperiodic one-dimensional photonic crystal, composed of high-temperature superconductor and semiconductor layers arranged within the crystal based on a Dodecanacci sequence, has been calculated using the transfer matrix method and the two-fluid model. The critical temperature of the superconductor depends on the hydrostatic pressure, while the semiconductor’s plasma frequency and dielectric constant were considered to be dependent on both the pressure and temperature applied. We have found that the transmittance spectrum shows the band gaps unfold

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