Дисертації з теми "Rough boundary"
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Alexander, William Nathan. "Sound from Rough Wall Boundary Layers." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/29246.
Повний текст джерелаPh. D.
Kutlar, Ahmet Ihsan. "Turbulant boundary layers on rough painted surfaces." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359178.
Повний текст джерелаDyer, Luke Oliver. "Parabolic boundary value problems with rough coefficients." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33276.
Повний текст джерелаTarada, F. H. A. "Heat transfer to rough turbine blading." Thesis, University of Sussex, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379448.
Повний текст джерелаRapetto, Marco. "Rough surfaces in contact : artificial intelligence and boundary lubrication." Licentiate thesis, Luleå tekniska universitet, Maskinelement, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25874.
Повний текст джерелаGodkänd; 2008; 20080512 (ysko)
Rapetto, Marco Pietro. "Rough surfaces in contact : artificial intelligence and boundary lubrication /." Luleå : Luleå University of Technology, 2008. http://epubl.ltu.se/1402-1757/2008/16/.
Повний текст джерелаRoss, Christopher Roger. "Direct and inverse scattering by rough surfaces." Thesis, Brunel University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318675.
Повний текст джерелаChang, Chung-Yie. "Boundary value problems for differential equations driven by rough signals." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299835.
Повний текст джерелаSmith, Benjamin Scott. "Wall Jet Boundary Layer Flows Over Smooth and Rough Surfaces." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/27597.
Повний текст джерелаPh. D.
Arens, Tilo. "The scattering of elastic waves by rough surfaces." Thesis, Brunel University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311560.
Повний текст джерелаGagné, Jean-François. "An improved method for modelling fully rough turbulent boundary layer flows." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq36888.pdf.
Повний текст джерелаTachie, Mark Francis. "Open channel turbulent boundary layers and wall jets on rough surfaces." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ63927.pdf.
Повний текст джерелаKreuter, Marcel [Verfasser]. "Vector-valued elliptic boundary value problems on rough domains / Marcel Kreuter." Ulm : Universität Ulm, 2019. http://d-nb.info/1177882434/34.
Повний текст джерелаStewart, Douglas John. "Finite element schemes for elliptic boundary value problems with rough coefficients." Thesis, Brunel University, 1998. http://bura.brunel.ac.uk/handle/2438/5529.
Повний текст джерелаSharma, Sanjib. "Uniform Flow Development Length in a Rough Laboratory Flume." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/theses/1620.
Повний текст джерелаWatt, Robert McFarlane. "Effects of surface roughness on the boundary-layer characteristics of turbine aerofoils." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330065.
Повний текст джерелаSen, Mehmet Ali. "Proper Orthogonal Decomposition Methodology to Understand Underlying Physics of Rough-Wall Turbulent Boundary Layer." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/SenMA2007.pdf.
Повний текст джерелаKerevanian, G. K. "Experimental investigation of turbulent boundary layers on uniform, well-defined rough walls." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269051.
Повний текст джерелаMeyers, Timothy Wade. "The Rough Wall High Reynolds Number Turbulent Boundary Layer Surface Pressure Spectrum." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/25880.
Повний текст джерелаMaster of Science
Forest, Jonathan Bradley. "The Wall Pressure Spectrum of High Reynolds Number Rough-Wall Turbulent Boundary Layers." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/31114.
Повний текст джерелаMaster of Science
Konidaris, Spyridon G. "Electromagnetic scattering from rough surfaces using the On-Surface Radiation Boundary Condition (OSRC) method." Thesis, Monterey, California. Naval Postgraduate School, 1990. http://hdl.handle.net/10945/30624.
Повний текст джерелаElectromagnetic scattering from rough surfaces is of prime importance in the engineering field since it affects communications, radar, remote sensing, acoustics, etc. The actual problem of scattering from rough surfaces is complicated and involves three dimensional scattering from either lossy or dielectric, electrically large surface. Integral equations are widely utilized to solve this kind of problem but this solution to the problem is generally computationally intensive. In the On-Surface Radiation Boundary Condition (OSRC) method, a higher order radiation condition is imposed directly on the surface of the scatterer. This reduces the integral equation for the scattered field to a line integral which can be easily evaluated numerically. In this thesis, the OSRC method is used to formulate the problem of scattering from periodic rough, two dimensional surfaces illuminated by a transverse magnetic, plane electromagnetic wave. Three geometric surfaces are considered. A comparison is made between the present formulation, the exact solution, and the physical optics approximation.
Sapkota, Deependra. "TRIPPING OF THE BOUNDARY LAYER DEVELOPMENT LENGTH OVER ROUGH AND FULLY TURBULENT SUBCRITICAL FLUME." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/theses/1801.
Повний текст джерелаMcClain, Stephen Taylor. "A discrete-element model for turbulent flow over randomly-rough surfaces." Diss., Mississippi State : Mississippi State University, 2002. http://library.msstate.edu/etd/show.asp?etd=etd-04032002-140007.
Повний текст джерелаGeorge, Jacob. "Structure of 2-D and 3-D Turbulent Boundary Layers with Sparsely Distributed Roughness Elements." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/27935.
Повний текст джерелаPh. D.
Bomminayuni, Sandeep Kumar. "Large eddy simulation of turbulent flow over a rough bed using the immersed boundary method." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34821.
Повний текст джерелаWang, Lu Ph D. Massachusetts Institute of Technology. "Self-shrinkers of mean curvature flow and harmonic map heat flow with rough boundary data." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67817.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (p. 59-63).
In this thesis, first, joint with Longzhi Lin, we establish estimates for the harmonic map heat flow from the unit circle into a closed manifold, and use it to construct sweepouts with the following good property: each curve in the tightened sweepout, whose energy is close to the maximal energy of curves in the sweepout, is itself close to a closed geodesic. Second, we prove the uniqueness for energy decreasing weak solutions of the harmonic map heat flow from the unit open disk into a closed manifold, given any H¹ initial data and boundary data, which is the restriction of the initial data on the boundary of the disk. Previously, under an additional assumption on boundary regularity, this uniqueness result was obtained by Rivière (when the target manifold is the round sphere and the energy of initial data is small) and Freire (for general target manifolds). The point of our uniqueness result is that no boundary regularity assumption is needed. Also, we prove the exponential convergence of the harmonic map heat flow, assuming that the energy is small at all times. Third, we prove that smooth self-shrinkers in the Euclidean space, that are entire graphs, are hyperplanes. This generalizes an earlier result by Ecker and Huisken: no polynomial growth assumption at infinity is needed.
by Lu Wang.
Ph.D.
Alveroğlu, Burhan. "The convective instability of the BEK system of rotating boundary-layer flows over rough disks." Thesis, University of Leicester, 2016. http://hdl.handle.net/2381/37977.
Повний текст джерелаWalshe, John D. "CFD modelling of wind flow over complex and rough terrain." Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/7827.
Повний текст джерелаRasnick, Matthew Byron. "The Noise of a Boundary Layer Flowing Over Discrete Roughness Elements." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/33202.
Повний текст джерелаMaster of Science
Mansour-Tehrani, Mehrdad. "Spacial distribution and scaling of bursting events in boundary layer turbulence over smooth and rough surfaces." Thesis, University College London (University of London), 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261297.
Повний текст джерелаJoseph, Liselle AnnMarie. "Pressure Fluctuations in a High-Reynolds-Number Turbulent Boundary Layer over Rough Surfaces of Different Configurations." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/79630.
Повний текст джерелаPh. D.
Repasky, Russell James. "Turbulent Boundary Layers over Rough Surfaces: Large Structure Velocity Scaling and Driver Implications for Acoustic Metamaterials." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/90796.
Повний текст джерелаMaster of Science
Aerodynamicists are often concerned with interactions between fluids and solids, such as an aircraft wing gliding through air. Due to frictional effects, the relative velocity of the air on the solid-surface is negligible. This results in a layer of slower moving fluid near the surface referred to as a boundary layer. Boundary layers regularly occur in the fluid-solid interface, and account for a sufficient amount of noise and drag on aircraft. To compensate for increases in drag, engines are required to produce increased amounts of power. This leads to higher fuel consumption and increased costs. Additionally, most boundary layers in nature are turbulent, or chaotic. Therefore, it is difficult to predict the exact paths of air molecules as they travel within a boundary layer. Because of its intriguing physics and impacts on economic costs, turbulent boundary layers have been a popular research topic. This study analyzed air pressure and velocity measurements of turbulent boundary layers. Relationships between the two were drawn, which fostered a discussion of future works in the field. Mainly, the simultaneous measurements of pressure on the surface and boundary layer velocity can be performed with understanding of the Pressure Poisson equation. This equation is a mathematical representation of the boundary layer pressure on the surface. This study also explored the possibility of turbulent-boundary-layer-driven-acoustic-metamaterials. Acoustic metamaterials contain hundreds of cavities which can collectively manipulate passing sound waves. A facility was developed at Virginia Tech to measure this effect, with aid from a similar laboratory at Exeter University. Microphone measurements showed the reduction of sound wave speed across the metamaterial, showing promise in acoustic manipulation. Applications in metamaterials in the altering of sound caused by turbulent boundary layers were also explored and discussed.
Zhang, Libiao. "Modelling uncertain decision boundary for text classification." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/102042/1/Libiao_Zhang_Thesis.pdf.
Повний текст джерелаGrissom, Dustin Leonard. "A Study of Sound Generated by a Turbulent Wall Jet Flow Over Rough Surfaces." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/28336.
Повний текст джерелаRen, Huiying. "Experimental Studies of Turbulent Boundary Layers Over a Rough Forward-facing Step and its Coarse Scale Resolution Approximations." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1292449621.
Повний текст джерелаMoon, Jiyoung. "Rheological Behavior of Complex Fluid with Deformable and Rigid Particles." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17106.
Повний текст джерелаLeaman, Nye Abigail. "Scattering of internal gravity waves." Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/238679.
Повний текст джерелаTournier, Simon. "Contribution à la modélisation de la diffusion électromagnétique par des surfaces rugueuses à partir de méthodes rigoureuses." Thesis, Toulouse, ISAE, 2012. http://www.theses.fr/2012ESAE0008/document.
Повний текст джерелаThis work is about the scattering by monodimensional rough surfaces. Surfaces presenting small scales of variations need a very refined mesh to finally capture the scattering field behaviour what increases the computational cost. Two aspects are considered : the reduction of the problemsize through an effective boundary condition incorporating the effect of rapid variations and the reduction of the number of iterations to solve the linear system arising from method of moments by a method based on Krylov subspace. Firstly, an homogenization process is used to convert the boundary condition on the rough interface into effective parameters. These parameters are determined by the solutions of auxiliary problems which involve the detailed profile of the interface. In the case of perfectly metallic surfaces, the process is applied to the E- and H-polarization and an Leontovich impedance of order 1 is deduced. The process is automatic and higher orders are derived for E-polarization. The homogenization process is also applied to dielectric rough interfaces. Secondly, a physically-based preconditioner is built with Floquet’s modes. Although the preconditioner has been designed for periodical surfaces, it was shown to be efficient in the case of truncated surfaces illuminated by a plane wave. The efficiency of both aspects is numerically illustrated for some configurations of interest
Kubwimana, Thierry. "Simulation de l'écoulement atmosphérique au voisinage d'une tête de tunnel." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEC023.
Повний текст джерелаThe design of a mechanical ventilation system in a tunnel requires to identify all the physical phenomena involved in the movement of the air in the tunnel. That is in order to establish the necessary ventilation capacities with regard to regulatory objectives. Atmospheric effects feature among the mechanisms likely to generate overpressures or depressions near the openings of a tunnel and consequently to induce or to modify the airflow established inside. This research work intends to contribute to a better understanding as well as a better consideration of the external atmospheric effects in tunnel ventilation studies.Experimental and numerical modeling have been completed. Wind tunnel tests were carried out in the atmospheric wind tunnel of the École Centrale de Lyon and used different techniques (PIV, hot wire anemometry, micromanometer) to measure the mean and turbulent statistics of the atmospheric flow in the vicinity of a tunnel. Time averaged (RANS) and filtered (LES) turbulence models were also used to simulate the atmospheric flow around a tunnel.The suitable representation of the unsteady turbulent atmospheric flow at the inlet of an LES computational domain remains an issue. During this work, we implemented a synthetic turbulence generator in the CFD code Fluent and, through comparison with experimental data, derived the optimal setup for the simulation of a fully rough atmospheric boundary layer.Thereafter, two tunnel configurations were studied by numerical and experimental means. In a first series of tests, the pressure field at the front section of a rectangular cavity was studied. The comparisons between the different approaches highlighted the influence of the geometry of the tunnel and the arrangement of the surrounding urban-like environment, as well as a better performance of the LES model in the description the turbulent flow. And in a second series of tests, we got closer to a realistic configuration and instrumented an open tunnel in which we could create an airflow directed towards the outside or the inside of the structure. The results showed a significant interaction between the atmospheric boundary layer and the three-dimensional wall jet from the tunnel
Rouzès, Maxime. "Etude expérimentale de l'hydrodynamique d'un écoulement turbulent à surface libre sur fond rugueux à faible submersion." Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/14164/1/rouzes.pdf.
Повний текст джерелаToussaint, Damien. "Couche limite turbulente sur paroi rugueuse : étude expérimentale et modélisation." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0122.
Повний текст джерелаTurbulent flows over rough walls can be found in various environmental and engineering situations. Focusing on aeronautical applications, unwanted rough surfaces are likely to decrease the overall efficiency of a system, skin friction, and heat transfer coefficients being generally increased compared to ideal smooth-wall situations. A careful account of the aerodynamic effects induced by surface roughness is therefore important in a design process, and several prediction strategies may be considered. The Discrete Element Roughness Method (DERM) is considered in the present study. This approach aims at resolving the averaged roughness effects and is derived by ensemble- and volume-averaging the Navier–Stokes equations, yielding three unknown terms in the momentum equation: the Reynolds stress and dispersive stress tensors and the average drag force acting on the roughness elements. The present work aims at proposing guidance for their modelling. First, a LDV measurement campaign was conducted to investigate turbulent boundary layer flows over rough surfaces. Measurements were especially performed within the roughness wake regions, that are not extensively investigated in the literature. Second, RANS simulations of turbulent channel flows over resolved rough surfaces were performed. The numerical results were then compared to the experimental data to assess the validity of the RANS simulations. Finally, these numerical results were analysed to highlight the behavior of the specific DERM terms and propose guidance for their modeling
Salizzoni, Pietro. "Mass and momentum transfer in the urban boundary layer." Ecully, Ecole centrale de Lyon, 2006. http://www.theses.fr/2006ECDL0015.
Повний текст джерелаDietz, Otto. "Linear and non-linear properties of light." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17474.
Повний текст джерелаAny optical experiment, any optical technology is only about one thing: Manipulating the properties of light through interaction with matter. This thesis will address two important issues in this broad context, in the linear and in the non-linear regime. In Part I, the well-known Bragg reflection is revised. Bragg reflection takes place whenever light interacts with a periodic structure. The famous Bragg condition relates the lattice spacing in a crystal to the wavelength which is effectively reflected by that lattice. In this thesis the Bragg reflection in dielectric waveguides is investigated. It is shown that the Bragg condition is not sufficient to describe the scattering situation in waveguides with corrugated boundaries. It is demonstrated, analytically and numerically, that corrugated boundaries cause a new type of reflection condition, which goes beyond the Bragg picture. This scattering mechanism, the Square Gradient Bragg Scattering, is known from statistical scattering approaches. It is connected to the curvature of the boundary and has a strong influence on the wave propagation in these systems. Here the first general theory for Square Gradient Bragg Scattering is presented, which allows for making predictions for single corrugated waveguides with arbitrary boundaries. Another important property of light is investigated in Part II of this thesis: The entanglement of two photons. Entanglement is a counter-intuitive phenomenon, because it has no classical analogy. It especially violates our assumption of local realism, because distant particles seemingly act on each other instantaneously. In this thesis a new tunable and portable source of photon pairs is designed. The photon pairs are created in non-linear crystals, but their entanglement is enforced in a purely geometrical manner. This geometrical approach makes the setup tunable. This is where the new design supersedes its predecessor, which will be discussed in detail. The entanglement of the generated photons is demonstrated experimentally.
Introïni, Clément. "Interaction entre un fluide à haute température et un béton : contribution à la modélisation des échanges de masse et de chaleur." Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0074/document.
Повний текст джерелаIn the late phases of some scenario of hypothetical severe accident in Pressurized Water Reactors, a molten mixture of core and vessel structures, called corium, comes to interact with the concrete basemat. The safety numerical tools are lumped parameter codes. They are based on a large averaged description of heat and mass transfers which raises some uncertainties about the multi-scale description of the exchanges but also about the adopted boundary layer structure in the vicinity of the ablation front. In this context, the aim of this work is to tackle the problem of the boundary layer structure by means of direct numerical simulation. This work joins within the more general framework of a multi-scale description and a multi-scale modeling, namely from the local scale associated with the vicinity of the ablation front to the scale associated with the lumped parameter codes. Such a multi-scale description raises not only the problem of the local description of the multiphase multicomponent flow but also the problem of the upscaling between the local- and the macro-scale which is associated with the convective structures within the pool of corium. Here, we are particularly interested in the building of effective boundary conditions or wall laws for macro-scale models. The difficulty of the multiphase multicomponent problem at the local scale leads us to consider a relatively simplified problem. Effective boundary conditions are built in the frame of a domain decomposition method and numerical experiments are performed for a natural convection problem in a stamp shaped cavity to assess the validity of the proposed wall laws. Even if the treated problem is still far from the target applications, this contribution can be viewed as a first step of a multi-scale modeling of the exchanges for the molten core concrete issue. In the more complicated case of multiphase multicomponent flows, it is necessary to have a direct numerical simulation tool of the flow at the local scale to build wall laws for macro-scale models. Here, the developed tool corresponds to a Cahn-Hilliard/Navier-Stokes model for a two-phase compositional system. It relies on a description of the system by three volume fractions and on a free energy composed by a two-phase part and a compositional part. The governing equations are derived in the frame of the thermodynamic of irreversible processes. They are solved on the basis of a finite element application of the object-oriented software component library PELICANS. Several numerical experiments illustrate the validity and the potentialities of application of this tool on two-phase compositional problems. Finally, using the developed tool, we tackle by means of direct numerical simulation the problem boundary layer structure in the vicinity of the ablation front for limestone-sand and siliceous concretes
Bey, Mohamed Amine. "Modélisation mathématique et simulations numériques des écoulements sanguins dans des artères avec ou sans stents." Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCD027/document.
Повний текст джерелаThis thesis is devoted to mathematical modeling and numerical simulations of the blood-flows in arteries in the presence of a vascular prosthesis of type stent. The presence of stent can be considered as a local perturbation of a smooth edge of flow, more precisely the walls artery can be seen as a strongly rough surface.Weare mainly interested in controlling the H² regularity of a simplified model which takes into account the impact of these stents when the blood flow is controlled by a Laplace equation (in link with the axial component rateof flow) with a Dirichlet boundary condition, in a domain with a rough board (according to a small parameter ε). First, we raise the question of existence and unicity of the solution of this model of blood-flow and we study the H² regularity using variational analysis methods. By a detailed study, we control the H² regularity of order O(ε−1). The second part is devoted to the study of the regularity H² regularity using multi-scale analysis.We prove that the H² norm of the solution of this model is singular of order O(ε−½). Moreover, we improve the convergence rate of the existing results on the construction of the multi-scale approximation. Finally, we present an error estimation and numerical results. These numerical results illustrate the well-founded of the error estimates on a practical level. We show the importance of the asymptotic methods that seem to be more effective than a direct computation
SU, ZI-YI, and 蘇子義. "Rough turbulent boundary layer under short-crested waves." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/70815213839789348475.
Повний текст джерелаShah, Mohammad Khalid. "Skin friction characteristics in smooth-wall, transitionally rough and fully rough turbulent boundary layer." 2004. http://hdl.handle.net/1993/15762.
Повний текст джерелаYUAN, JUNLIN. "Large-Eddy Simulations of Accelerating Boundary Layer Flows Over Rough Surfaces." Thesis, 2011. http://hdl.handle.net/1974/6846.
Повний текст джерелаThesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2011-10-17 11:19:08.063
Morgan, Jonathan Philip. "Linear and Non-linear Interactions in a Rough-Wall Turbulent Boundary Layer." Thesis, 2019. https://thesis.library.caltech.edu/11453/17/Jonathan-Morgan-final-thesis-submission.pdf.
Повний текст джерелаThis thesis explores the linear and non-linear interactions which take place in a rough-wall turbulent boundary through experiments and modeling. In order to derive physics-based models for the relation between roughness geometry and flow physics, two very simple periodic roughnesses were 3D printed and placed in a boundary layer wind tunnel for separate experiments. Hot-wire measurements were taken at a grid of points within a single period of the roughness in order to map the spatial variation of important flow statistics in way that allows correlation back to the roughness geometry. Time averaged streamwise velocity and the power spectrum of instantaneous streamwise velocity were both found to vary coherently with the roughness. The spatial variation of the time averaged velocity was identified as the linear result of the roughness, as it has identical wavenumber and frequency to the static roughness geometry. Modeling the time-averaged velocity field as a response mode of the linear resolvent operator was found to be reasonable for certain wavenumbers. The spatial distribution of the power spectrum was shown to be a non-linear effect of the roughness; the power spectrum only measures the energy of convecting modes, which necessarily have non-zero frequency and cannot correlate linearly to the static roughness. The spatial modulation of the power spectrum was found to be indicative of non-linear triadic interactions between the static velocity Fourier modes and pairs of convecting modes, as allowed by the Navier-Stokes equations. A low-order model for these interactions, and their effect on the power spectrum, was constructed using resolvent response modes to represent all velocity Fourier modes. The model was found to qualitatively predict the modulation of the power spectrum for several sets of wavenumbers. The success of such a simple model suggests that it presents a useful low-order understanding of non-linear forcing between scales in rough-wall boundary layers.
Joshi, Sumedh Mohan. "Quantifying three dimensional effects in acoustic rough surface scattering." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-05-3377.
Повний текст джерелаtext