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Showing 1 to 14 of 14 for “"rough walls"”.
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The Structure of Turbulence Over Smooth and Rough Walls
Several spanwise lengthscales are shown to vary linearly with distance from the wall, revealing self-similar growth of spanwise structure in an average sense. However, inspection of the data suggests individual structures do not grow strictly self-similarly in time. It is proposed that additional …
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Inner-outer interactions in a rough-wall turbulent boundary layer
… understanding of inner-outer interactions in rough-wall turbulent boundary layers. These interactions were recently established over smooth-wall turbulent boundary layers as modulating interactions, where the outer layer large scales amplitude and frequency modulate the near-wall small scales. …
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Light interaction
… part to reveal a building halfway up. Its thick, rough walls are pulled apart at moments, allowing light and movement into the space. The path leads between the walls. The narrow passage continues in a counter-clockwise motion up a staircase, leading you towards the light; moving from opacity to …
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The Rough Wall High Reynolds Number Turbulent Boundary Layer Surface Pressure Spectrum
… have been very few studies investigating the rough wall pressure spectra under fully rough flows, which are relevant to many common engineering applications operating within this regime. This investigation uses the Virginia Tech Stability Wind Tunnel to perform experiments on a series of high …
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Open-Channel Flow With Roughness Elements of Different Spanwise Aspect Ratios: Turbulence Structure and Numerical Modeling
Under rough-wall conditions the length scales governing the flow dynamics in the inner region of boundary layers are no longer determined by the flow itself (i.e. $\nu$/$u\sb*$ for smooth walls), but rather independently specified by the real dimensions of the elements. In particular, the ratio …
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Geometry-Aware Modeling of Rough-Wall Turbulence Using Reynolds-Averaged Navier-Stokes (RANS) Frameworks
Turbulent flow over rough walls is widespread in engineering systems and plays a critical role in drag prediction, energy efficiency, and transport processes in internal and external flows. Despite extensive research, the representation of roughness effects in Reynolds-Averaged Navier–Stokes (RANS) …
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Amplitude modulation of velocity and wall shear stress in turbulent channel flow with hemispherical roughness
… for the theoretical modeling of wall turbulence, rough surfaces are more widely encountered in practical engineering problems. The presence of roughness elements greatly modifies the drag, heat-transfer and aerodynamic characteristics of surfaces, which involves strong interplay between the …
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Fluid Dynamics and Surface Pressure Fluctuations of Turbulent Boundary Layers Over Sparse Roughness
Turbulent boundary layers over rough surfaces are a common, yet often overlooked, problem of practical engineering importance. Development of correlations between boundary layer parameters that can be used in turbulence models and the surface geometry is the only practical option for solving these …
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Fluid Dynamics and Surface Pressure Fluctuations of Two-Dimensional Turbulent Boundary Layers Over Densely Distributed Surface Roughness
… of three-dimensional densely distributed surface roughness. A 3-velocity component laser Doppler velocimeter was used to measure instantaneous velocities. These measurements permitted an independent estimate of skin friction on the surfaces using a momentum balance approach, and the validity of …
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The Wall Pressure Spectrum of High Reynolds Number Rough-Wall Turbulent Boundary Layers
The presence of roughness on a surface subject to high Reynolds number flows promotes the formation of a turbulent boundary layer and the generation of a fluctuating pressure field imposed on the surface. While numerous studies have investigated the wall pressure fluctuations over zero-pressure …
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The dynamics of the outer region of wall-bounded turbulence : La dinámica de la zona exterior en la turbulencia de pared
… show similar effects as those reported on rough-walled flows, and our wall- forcing corresponds to equivalent sand roughness in the fully rough regime. The changes on the flow structure imposed by the wall forcing are essentially limited to the roughness sublayer; a layer near the wall …
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Pressure Fluctuations in a High-Reynolds-Number Turbulent Boundary Layer over Rough Surfaces of Different Configurations
… fluctuations under a high Reynolds Number, rough-wall, turbulent, boundary layer have been studied in the Virginia Tech Stability Wind Tunnel. Rough surfaces of varying element height (1-mm, 3-mm), shape (hemispheres, cylinders) and spacing (5.5-mm, 10.4-mm, 16.5-mm) were investigated in …
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Incipient Motion Under Shallow Flow Conditions
Laboratory experiments were conducted to investigate the effect of low relative depth and high Froude number on the dimensionless critical shear stress (Shields parameter). Spherical particles of four different densities and an 8mm diameter were used as movable test material. The relative depth …