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Showing 1 to 18 of 18 for “"near-wall turbulence"”.
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Near-wall turbulence in the transitionally rough regime
… flow by roughness before the canonical smooth-wall turbulence is entirely altered. To study this regime, direct numerical simulations of turbulent flows over transitionally rough surfaces are conducted. First, a modulated triple decomposition of the flow is proposed to study the effect that …
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Regeneration mechanisms of organized structures in near-wall turbulence
… of longitudinal coordinate) decaying and forced turbulence and 3D turbulent channel flows in order to ascertain the sustenance mechanism of near-wall turbulence by investigating the mechanism of streak formation. We found the existence of streaks in quasi-2D flows thus demonstrating that contrary …
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The influence of superhydrophobic surfaces on near-wall turbulence
… slip and the texturing of the surface have on turbulence over superhydrophobic surfaces. It is shown that, after filtering out the texture-induced flow, the background, overlying turbulence experiences the surface as a homogeneous slip boundary condition. For texture sizes, expressed in wall …
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An Experimental Study of Near-Wall Turbulence Properties in Highly Drag Reduced Pipe Flows of Pseudoplastic Polymer Solutions
Made available in DSpace on 2014-12-13T18:55:38Z (GMT). No. of bitstreams: 1 7820916.pdf: 7029582 bytes, checksum: 692c2bf438064de8029607fec8446b88 (MD5) Previous issue date: 1978
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A Parallel Solution-Adaptive Method for Turbulent Non-Premixed Combusting Flows
… refinement criteria. For calculations of near-wall turbulence, an automatic near-wall treatment readily accommodates situations during adaptive mesh refinement where the mesh resolution may not be sufficient for directly calculating near-wall turbulence using the low-Reynolds-number …
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Amplitude modulation of velocity and wall shear stress in turbulent channel flow with hemispherical roughness
"Near-wall turbulence cycles tend to be self-sustained in low Reynolds number wall-bounded turbulent flows. However, large-scale structures that reside in the outer region of the flow grow more energetic as Reynolds number increases and impart strong ""footprints"" on the near-wall turbulence. In …
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The Space-time Structure of an Axisymmetric Turbulent Boundary Layer Ingested by a Rotor
… applications, urban air-transportation and turbulence ingestion noise. The combined effect of lateral curvature and streamwise pressure gradient are examined on the mean flow, turbulence structure, velocity correlations and wall pressure fluctuations. Additionally, the upstream influence of …
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Turbulent Boundary Layer Flow Over a Bump
… and flow skewing alter the development of turbulence. Experimental measurements were acquired at multiple locations across the surface to capture both near-wall and outer-layer flow behavior under varying degrees of pressure gradient and surface curvature. The findings reveal that, while …
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Physical modelling of colloidal slurry flows
… the aggregate, enhancing the level of fluid turbulence. The centre-line and near wall turbulence intensities are enhanced in the presence of aggregates, while dispersed suspensions have negligible effect on modulating the fluid turbulence. Measurement of the streamwise RMS shows two critical …
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Experimental visualization of the near-boundary hydrodynamics about fish-like swimming bodies
This thesis takes a look at the near boundary flow about fish-like swimming bodies. Experiments were performed up to Reynolds number 106 using laser Doppler velocimetry and particle imaging techniques. The turbulence in the boundary layer of a waving mat and swimming robotic fish were investigated. …
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Multiscale environmental flow dynamics: particle settling, turbulence modulation, and tornadic vortices
… whereas viscous dominated regimes yield rectilinear descent. Ensemble measurements reveal that particle proximity suppresses drag relative to isolated behaviour, while crossing a density interface induces a transient slowdown governed by entrainment‑driven buoyancy forces. Pair‑dispersion …
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The Wall Pressure Spectrum of High Reynolds Number Rough-Wall Turbulent Boundary Layers
… While numerous studies have investigated the wall pressure fluctuations over zero-pressure gradient smooth walls, few studies have examined the effects of surface roughness on the wall pressure field. Additionally, due to the difficulties in obtaining high Reynolds number flows over fully …
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Wall Modeled Large Eddy Simulation of Flow over a Wall Mounted Hump
… numerical simulation (DNS). However, LES of wall-bounded flows still requires a very high grid resolution in the inner wall layer making its widespread use difficult. Different attempts have been made in the past time to overcome this problem by modeling the near wall turbulence instead of …
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Particle motion in the near bed region of a turbulent open channel flow: Implications for bedload transport by saltation and sediment entrainment into suspension
… in the transport of sediment particles in the near bed region of a turbulent open channel flow. Two different aspects of this phenomenon are examined, namely the mode of transport denoted as saltation, and the process of particle entrainment into suspension. The main approach followed is …
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The effect of texture granularity on turbulence
… L⁺ ≤ 20, it has been previously discussed that turbulence remains smooth-wall-like, other than experiencing an apparent origin offset for different flow components. For slip/no-slip textures, this effect reduces to the flow experiencing slip conditions in the streamwise and spanwise directions …
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Turbulence Modelling for Complex Flows in Turbomachinery
… physics of this complex flow, the RANS turbulence closure models and a hybrid RANS-LES method are developed and extended. The improved RANS and hybrid RANS-LES models are shown to be able to predict the corner separation flows with significantly improved accuracy, and are expected to be …
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Control of the buffer and logarithmic layers in wall-bounded turbulent flows
… separately the buffer and logarithmic layers in wall-bounded turbulent flows. In the case of buffer-layer control, we examine the effect on near-wall turbulence of displacing the apparent, virtual origins perceived by different components of the overlying flow. This mechanism is commonly reported …
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Turbulent flows over canopies
… larger than the characteristic scales of near-wall turbulence, $s^+ \gtrsim 100$. We focus on the effect of the canopy on the background turbulence, the part of the flow that remains once the element-induced flow is filtered out. In channel flows, the distribution of the total stress is …