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Showing 1 to 11 of 11 for “"Roughness Sublayer"”.
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Experimental study of low-order models of highly-irregular roughness and their impact on turbulent boundary layers
… scales present within irregular surface roughness on a turbulent boundary layer under both developing- and developed-flow conditions. Low-order representations of highly irregular surface roughness replicated from a turbine-blade damaged by deposition of foreign materials were generated …
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Experimental Study of Low-Order Models of Highly-Irregular Roughness and Their Impact on Turbulent Boundary Layers
The stereo-PIV measurements deep within the roughness sublayer at y = 0.047delta reveal a wealth of information about roughness-induced effects, including the tendency of the roughness to promote 'channeling' of the flow in the form of low- and high-momentum pathways as noted in contour maps of the …
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Experimental Investigation of Highly Irregular Roughness Effects in Wall Turbulence
… the smooth wall, both within and outside the roughness sublayer, to further assess the possibility of structural modifications due to roughness. Hairpin vortex packets, commonly observed in smooth-wall turbulence, are observed often in the outer layer of the rough-wall flow. As in smooth-wall …
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Open-Channel Flow With Roughness Elements of Different Spanwise Aspect Ratios: Turbulence Structure and Numerical Modeling
… flow divided by the characteristic height of the roughness element (i.e. the spanwise aspect ratio $\lambda\sb{y}$) is regarded as an important parameter that determines the turbulence structure of the so-called roughness sublayer through the associated eddy-shedding process. The present work …
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Erweiterung der `Localized Near Field' Theorie zur Bestimmung von Quellstärken bei beliebiger thermischer Schichtung in einem Waldbestand
… time to examine the effects of the so called roughness sublayer. To apply the LNF during arbitrary thermal stratification it is necessary to find parametrisations for the input parameters standard deviation of vertical velocity and Lagrangian integral time scale. These are derived from values …
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Amplitude modulation of velocity and wall shear stress in turbulent channel flow with hemispherical roughness
… 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 pressure and viscous effects but is difficult to measure experimentally in the intermediate vicinity …
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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
… 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 whose height is proportional to a length scale defined in terms of the …
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The Role of Turbulence on the Entrainment of a Single Sphere and the Effects of Roughness on Fluid-Solid Interaction
Incipient motion criterion in sediment transport is very important, as it defines the flow condition that initiates sediment motion, and is also frequently employed in models to predict the sediment transport at higher flow conditions as well. In turbulent flows, even a reasonably accurate …
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Geometry-Aware Modeling of Rough-Wall Turbulence Using Reynolds-Averaged Navier-Stokes (RANS) Frameworks
… extensive research, the representation of roughness effects in Reynolds-Averaged Navier–Stokes (RANS) turbulence models remains fundamentally challenging. Classical approaches rely on hydrodynamic equivalence, typically through the equivalent sand-grain roughness height and empirical shifts …
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Flow regimes in canopy turbulence
… term `canopy' refers to a group of substantial roughness elements protruding into the flow, which generally results in two distinct regions of interest: the near-canopy region, where the flow is directly influenced by the canopy, and the outer layer, where the flow sufficiently far above the …
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Turbulent flows over canopies
… The term `canopy' is used to refer to tall roughness elements in the flow. Sparse canopies typically have large element spacings and allow turbulent eddies to penetrate between the elements, whereas dense canopies have small spacings and preclude the penetration of turbulent eddies within …