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Article
Open AccessScalar Fluxes Near a Tall Building in an Aligned Array of Rectangular Buildings
Scalar dispersion from ground-level sources in arrays of buildings is investigated using wind-tunnel measurements and large-eddy simulation (LES). An array of uniform-height buildings of equal dimensions and a...
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Article
Open AccessAre Urban-Canopy Velocity Profiles Exponential?
Using analyses of data from extant direct numerical simulations and large-eddy simulations of boundary-layer and channel flows over and within urban-type canopies, sectional drag forces, Reynolds and dispersiv...
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Article
Measurements and Computations of Flow in an Urban Street System
We present results from laboratory and computational experiments on the turbulent flow over an array of rectangular blocks modelling a typical, asymmetric urban canopy at various orientations to the approach f...
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Chapter and Conference Paper
The Streamwise Turbulence Intensity – A Comparison between Smooth and Rough Wall Turbulent Boundary Layers
Clear differences in turbulence intensity profiles in smooth, transitional and fully rough zero-pressure gradient boundary layers are demonstrated, using the diagnostic plot (u′/U vs. U/U ∞ where
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Chapter and Conference Paper
On Subgrid-Scale Model Implementation for a Lee-Wave Turbulent Patch in a Stratified Flow above an Obstacle
Results of application of a subgrid-scale (SGS) model to describe turbulence arising in a stably stratified flow above an obstacle are shown for high Schmidt/Prandtl numbers. An appropriate SGS Schmidt/Prandtl...
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Article
Large-Eddy Simulation of Heat Transfer from a Single Cube Mounted on a Very Rough Wall
The local thermal effects in the wake of a single cube with a strong heated rear face, representing a large building in an urban area, are studied using large-eddy simulations (LES) for various degrees of heat...
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Article
Some Measurements of Surface Drag in Urban-Type Boundary Layers at Various Wind Angles
Using experimental data obtained in naturally grown boundary layers over a generic urban-type roughness (height h) it is shown that the surface drag is strongly dependent on the flow direction with respect to the...
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Article
Calibration and use of a MEMS surface fence for wall shear stress measurements in turbulent flows
Microelectromechanical systems (MEMS) sensors are increasingly used for measurements in fluid dynamics since, because of their inherently compact size, they allow access to the information that was previously ...
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Article
On the effects of free-stream turbulence on axisymmetric disc wakes
Wind tunnel experiments have been used to study the effects of free-stream turbulence on the axisymmetric wake behind a disc. The disc and its wake were introduced to various turbulent streams having various l...
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Article
Large-Eddy Simulation of Dispersion from Line Sources in a Turbulent Channel Flow
Large-eddy simulations of the dispersion from scalar line sources at various locations within a fully developed turbulent channel flow at Re = uh/ν = 10,400 are presented. Both mean and fluctuating scalar quantit...
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Article
Wind-Direction Effects on Urban-Type Flows
Practically all extant work on flows over obstacle arrays, whether laboratory experiments or numerical modelling, is for cases where the oncoming wind is normal to salient faces of the obstacles. In the field,...
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Article
Turbulence in rough-wall boundary layers: universality issues
Wind tunnel measurements of turbulent boundary layers over three-dimensional rough surfaces have been carried out to determine the critical roughness height beyond which the roughness affects the turbulence ch...
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Article
Large-Eddy Simulation of Dispersion from Surface Sources in Arrays of Obstacles
Towards meeting the objective of simulating heat transfer processes in urban areas, the study of dispersion from a scalar (ground) surface area source has been addressed as a first step, since dispersion from ...
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Chapter and Conference Paper
Very-Rough-Wall Channel Flows: A DNS Study
Highly resolved Direct Numerical Simulations (DNS) of channel flows over staggered arrays of wall mounted cubes are presented and discussed. Attention is concentrated on the spatially averaged mean velocity pr...
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Chapter and Conference Paper
Internal Wave Breaking in Stratified Flows Past Obstacles
Turbulent patches occurring in environmental flows can arise from breaking internal waves generated topographically. The convective overturning of waves leads to shear instability and then to turbulence which ...
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Chapter and Conference Paper
Turbulent flow over rough walls
The nature of turbulent boundary layer flow over rough walls is discussed, with emphasis on the issues of zero-plane displacement, turbulence characteristics and how the latter may depend on roughness height a...
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Article
Efficient Generation of Inflow Conditions for Large Eddy Simulation of Street-Scale Flows
Using a numerical weather forecasting code to provide the dynamic large-scale inlet boundary conditions for the computation of small-scale urban canopy flows requires a continuous specification of appropriate ...
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Article
Large-Eddy Simulation of Flows over Random Urban-like Obstacles
Further to our previous large-eddy simulation (LES) of flow over a staggered array of uniform cubes, a simulation of flow over random urban-like obstacles is presented. To gain a deeper insight into the effect...
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Article
Measurements in an urban-type boundary layer
Wind tunnel measurements of the boundary layer flow over a very rough surface comprising a staggered array of cubes are presented and discussed. Attention is concentrated on the near-wall region, including the...
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Chapter
LES for Street-Scale Environments and Its Prospects
In this paper we raise several issues, e.g. resolution, Reynolds number dependency, mesh quality and inflow boundary conditions for Large-Eddy Simulation (LES) of street scale flows, scalar dispersion and heat...
