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Showing 1 to 20 of 22 for “"Turbulent channel flow"”.
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Optimal Large -Eddy Simulation of Turbulent Channel Flow
… a direct numerical simulation (DNS) of a plane channel at a friction Reynolds number of 587. Due to the limited number of realizations, estimates of the model term are global only in the streamwise and spanwise directions and local in the wall-normal direction. Measurements of the a priori error …
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Modification of Turbulent Channel Flow by Passive and Additive Devices
… what would be experienced with a Newtonian fluid flowing turbulently at the same rate. A solution of 2000 ppm tallow-(tris-hydroxyethyl)-ammonium acetate (or Ethoquad T/13/50) and sodium salicylate is investigated in this study. The instantaneous streamwise and normal velocity fluctuations were …
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Structure of turbulent channel flow perturbed by cylindrical roughness elements
… modifications imposed in fully-developed turbulent channel flow by an isolated, wall-mounted circular cylinder. The cylinder height is chosen to specifically extend into the logarithmic layer of the flow in order to study its perturbation of the larger flow scales that embody a significant …
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Experimental Investigation of Acceleration and Velocity Fields in Turbulent Channel Flow
… effects dominate the smaller scales of the flow. Comparison between the bulk convective-derivative and time-derivative spectra illustrate this behavior. At low wavenumbers, the bulk convective-derivative and time-derivative spectra coincide with one another, implying that the larger scales …
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Transport processes in a direct numerical simulation of turbulent channel flow
… time-dependent, three-dimensional turbulent flow in a channel is used to investigate turbulent transport processes. Detailed properties of the turbulent velocity field are presented. Three different transport processes are explored using this extensive data base. The first is the …
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Point source dispersion in a direct numerical simulation of turbulent channel flow
… located in a Direct Numerical Simulation of turbulent channel flow is studied. An algorithm for tracking fluid particles or molecular (or thermal) markers is developed and tested. Accurate estimates of a number of Lagrangian characteristics of the flow, necessary for the description of the …
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A direct numerical simulation of fully developed turbulent channel flow with passive heat transfer
… direct numerical simulation of a fully developed turbulent channel flow with passive heat transfer is performed. The time-dependent three-dimensional Navier-Stokes equations and advection-diffusion equation are solved numerically using a pseudospectral technique with 1,064,960 grid points in …
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Amplitude modulation of velocity and wall shear stress in turbulent channel flow with hemispherical roughness
… 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 addition, recent experiments in high …
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Study of the role of differential diffusion and equation of state on the features of stably stratified turbulent channel flow using direct numerical simulations
Stably stratified turbulent flows are observed in many systems, ranging from engineering applications to environmental flows. The density variation in such flows, particularly that observed in water bodies depends on temperature and salinity (salt content) through an equation of state (EoS). The …
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Master-mode set of turbulent 3D channel flow
Turbulent flow fields can be expanded into a series in a set of basic functions. Theterms of such series are often called modes. A master-mode-set is a subset of these modes, the time-history of which uniquely determines the time history of the entire turbulent flow provided that this flow is …
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Interaction Between a Spherical Particle and Wall -Bounded Flows at Finite Reynolds Number
… of a finite-sized particle embedded in a turbulent channel flow. Particles of various sizes have been located at two specific wall-normal locations, the buffer region and the channel center. Near-wall region mechanisms are observed consisting of such different events as bursting, sweep, …
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Large Eddy Simulations of high Reynolds number Complex Flows with Synthetic Inlet Turbulence
… application to complex high Reynolds number turbulent flows. The primary challenge in wall bounded flows is the need for very fine grids in the vicinity of walls, which makes LES impractical at high Reynolds numbers. An additional challenge is the accurate representation of inlet turbulent …
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Towards Optimal Large-Eddy Simulation of Wall-Bounded Flows
… addressed via a review of the OLES simulation of turbulent channel flow performed by Das (2004). In this approach, a buffer region with zero velocity is attached adjacent to the wall, and the extended velocity field is filtered using a Fourier-cutoff filter in all directions. The instantaneous …
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Modeling Cumulative Damage to Flow Surfaces and Assessing its Impact on Wall Turbulence
… Particle-image velocimetry measurements of flow at a friction Reynolds number around 1825 over various topographical models were gathered in turbulent channel flow. The cumulative impact of these reduced-order models on wall turbulence was then assessed by comparing mean velocities, Reynolds …
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A Filtered-Wall Formulation for Large -Eddy Simulation of Wall -Bounded Turbulence
… (LES) is a promising prediction technique for turbulent flows where only the largest scales of turbulence are simulated, while the effects of the small scales are modeled. However, the application of LES in engineering flows is limited largely by difficulties in LES modeling near walls; this is …
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Large Eddy Simulation of Boundary Layer Combustion
Numerical simulations of turbulent non-premixed flames occurring in the presence of solid surfaces is a prevalent topic of interest due to the complexity of the near wall physics and the technical modeling challenges it presents. Near wall combustion phenomena is relevant in a variety of combusting …
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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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Numerical Prediction of Drag Reduction and Interfacial Shapes Over Superhydrophobic Surfaces
… and surface properties. Both laminar and turbulent regimes are investigated. Direct numerical simulation (DNS) is used to study the drag reduction by superhydrophobic surfaces (SHS) in laminar channel flow. Resolved multiphase simulations using the volume-of-fluid (VOF) methodology are …
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Development and application of a dispersed two-phase flow capability in a general multi-block Navier Stokes solver
… during take off and landing, distorted intake flows during low altitude maneuvers, and hot gas ingestion during artillery firing. The focus of this thesis is to study ingestion of debris; specifically sand. The region of interest being the internal cooling ribbed duct of the turbine blade. The …
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Prediction of Trailing Edge Noise from Two-Point Velocity Correlations
… using the direct numerical simulation of a turbulent channel flow by Moser et al. (1998). Two-point velocity and vorticity statistics of this data set were obtained by averaging 41 instantaneous fields. For comparisons purposes, experimental boundary layer data by Adrian et al. (2000) was …
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