scholarly journals A Kriging-based elliptic extended anisotropic model for the turbulent boundary layer wall pressure spectrum

2018 ◽  
Vol 840 ◽  
pp. 25-55 ◽  
Author(s):  
Myriam Slama ◽  
Cédric Leblond ◽  
Pierre Sagaut
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Correlation Coefficients ◽  
Space Time ◽  
Wall Pressure ◽  
Anisotropic Model ◽  
Velocity Correlation ◽  
New Model ◽  
Wall Pressure Fluctuations

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 model, referred to as the extended anisotropic model, to evaluate the latter in all regions of the boundary layer. This model is an extension of the simplified anisotropic model of Gavin (PhD thesis, 2002, The Pennsylvania State University, University Park, PA) which was developed for the outer part of the boundary layer. It relies on a new expression for the spatial velocity correlation function and new parameters calibrated using the direct numerical simulation results of Sillero et al. (Phys. Fluids, vol. 26, 2014, 105109). Spatial correlation coefficients are related to space–time coefficients with the elliptic model of He & Zhang (Phys. Rev. E, vol. 73, 2006, 055303). The turbulent quantities necessary for the pressure computation are obtained by Reynolds-averaged Navier–Stokes solutions with a Reynolds stress turbulence model. Then, the pressure correlations are evaluated with a self-adaptive sampling strategy based on Kriging in order to reduce the computation time. The frequency and wavenumber–frequency wall pressure spectra obtained with the KEEAM agree well with empirical models developed for turbulent boundary layer flows without pressure gradient.

Predicting Turbulent Boundary Layer Wall Pressure Fluctuations in Adverse Pressure Gradients

2005 ◽  
Author(s):  
Frank J. Aldrich
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Pressure Fluctuations ◽  
Adverse Pressure Gradient ◽  
Wall Pressure ◽  
Prediction Tool ◽  
Pressure Gradients ◽  
Wall Pressure Fluctuations ◽  
The Difference

A physics-based approach is employed and a new prediction tool is developed to predict the wavevector-frequency spectrum of the turbulent boundary layer wall pressure fluctuations for subsonic airfoils under the influence of adverse pressure gradients. The prediction tool uses an explicit relationship developed by D. M. Chase, which is based on a fit to zero pressure gradient data. The tool takes into account the boundary layer edge velocity distribution and geometry of the airfoil, including the blade chord and thickness. Comparison to experimental adverse pressure gradient data shows a need for an update to the modeling constants of the Chase model. To optimize the correlation between the predicted turbulent boundary layer wall pressure spectrum and the experimental data, an optimization code (iSIGHT) is employed. This optimization module is used to minimize the absolute value of the difference (in dB) between the predicted values and those measured across the analysis frequency range. An optimized set of modeling constants is derived that provides reasonable agreement with the measurements.

Characterization of the Response of a Curved Elastic Shell to Turbulent Boundary Layer

2010 ◽  
Author(s):  
Francesca Magionesi ◽  
Elena Ciappi
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Scale Model ◽  
Spectral Densities ◽  
Flow Parameters ◽  
Wall Pressure Fluctuations

For the effective operation of sonar system mounted inside the bulbous of a fast ship, it is important to reduce all the possible noise and vibration sources that cause the dome to vibrate thus radiating noise and interfering with sonar sensor response. In particular, pressure fluctuations induced by the turbulent boundary layer on the surface of the sonar dome represent one of the major sources of self-noise for the on board sensors. Calculation of the structural vibrations and of the noise radiated inside the dome requires as a first step the characterization of the frequency spectra of turbulent boundary layer excitation. Most of the literature related to wall pressure fluctuations is devoted to the study of equilibrium turbulent boundary layers on flat plates in zero pressure gradient (ZPG) flow, for which scaling laws for the power spectral densities and empirical models for the cross spectral densities are well established. The turbulent boundary layer on the bulbous can present several differences with respect to the canonical case because of the presence of hull surface curvatures and of the free water surface that produce pressure gradient variation along the bulbous surface. Moreover, hydrodynamic coincidence effects play a markedly different role in the underwater problem than in the aerodynamic problem. Therefore, an experimental campaign was performed in a towing tank to measure wall pressure fluctuations at different locations along a large scale model of a bulbous and to investigate their spectral characteristics in terms of auto and cross spectral densities. Boundary layer mean flow parameters were obtained with a finite volume code solving the Reynolds Averaged Navier Stokes Equations. The auto spectral densities (ASD) of the measured wall pressure fluctuations were scaled using different combinations of inner and outer flow parameters in order to make ASD independent of the tested conditions i.e. of Reynolds number. The modelled load was used as input for a numerical procedure aimed at evaluating the dynamical response of a section of the bulbous under analysis. The validation of this procedure was experimentally obtained through the measurements of the vibrational response of an elastic section inserted into the bulbous model. Moreover, this comparison indirectly provides additional insights on the physics of wall pressure fluctuations for complex flows.

Wall Pressure Fluctuations in an Axisymmetric Turbulent Boundary Layer under Strong Adverse Pressure Gradient

2020 ◽  
Author(s):  
N. Agastya Balantrapu ◽  
Daniel J. Fritsch ◽  
Anthony J. Millican ◽  
Christopher Hickling ◽  
Aldo Gargiulo ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Pressure Fluctuations ◽  
Adverse Pressure Gradient ◽  
Wall Pressure ◽  
Wall Pressure Fluctuations

scholarly journals Analytical models of the wall-pressure spectrum under a turbulent boundary layer with adverse pressure gradient

2019 ◽  
Vol 877 ◽  
pp. 1007-1062 ◽  
Author(s):  
G. Grasso ◽  
P. Jaiswal ◽  
H. Wu ◽  
S. Moreau ◽  
M. Roger
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Pressure Fluctuations ◽  
Adverse Pressure Gradient ◽  
Wall Pressure ◽  
Analytical Models ◽  
Function Technique ◽  
Fast Evaluation ◽  
Wall Pressure Fluctuations

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 a joint normal probability distribution of the turbulent field. The functional expression of the turbulence statistics is shown to be the most critical point for a correct representation of the wall-pressure spectrum. The effect of various assumptions on the shape of the longitudinal correlation function of turbulence is assessed in the first place with purely analytical considerations using an idealised flow model. Then, the effect of the hypothesis on the spectral distribution of boundary-layer turbulence on the resulting wall-pressure spectrum is compared with the results of direct numerical simulation computations and pressure measurements on a controlled-diffusion aerofoil. The boundary layer developing over the suction side of this aerofoil in test conditions is characterised by an adverse pressure gradient. The final part of the paper discusses the numerical aspect of wall-pressure spectrum computation. A Monte Carlo technique is used for a fast evaluation of the multi-dimensional integral formulation developed in the theoretical part.

The scaling of the wall pressure fluctuations in polymer-modified turbulent boundary layer flow

2000 ◽  
Vol 108 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Timothy A. Brungart ◽  
Wayne J. Holmberg ◽  
Arnold A. Fontaine ◽  
Steven Deutsch ◽  
Howard L. Petrie
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Boundary Layer Flow ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Wall Pressure Fluctuations ◽  
Turbulent Boundary Layer Flow ◽  
Layer Flow
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