Michael Heisel
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View article: The vertical-velocity skewness in the inertial sublayer of turbulent wall flows
The vertical-velocity skewness in the inertial sublayer of turbulent wall flows Open
Empirical evidence is provided that within the inertial sublayer (i.e. logarithmic region) of adiabatic turbulent flows over smooth walls, the skewness of the vertical-velocity component $S_w$ displays universal behaviour, being a positive…
View article: Stochastic modal velocity field in rough-wall turbulence
Stochastic modal velocity field in rough-wall turbulence Open
Stochastically generated instantaneous velocity profiles are used to reproduce the outer region of rough-wall turbulent boundary layers in a range of Reynolds numbers extending from the wind tunnel to field conditions. Each profile consist…
View article: The vertical velocity skewness in the atmospheric boundary layer without buoyancy and Coriolis effects
The vertical velocity skewness in the atmospheric boundary layer without buoyancy and Coriolis effects Open
One of the main statistical features of near-neutral atmospheric boundary layer (ABL) turbulence is the positive vertical velocity skewness $Sk_w$ above the roughness sublayer or the buffer region in smooth-walls. The $Sk_w$ variations are…
View article: The vertical-velocity skewness in the inertial sublayer of turbulent wall flows
The vertical-velocity skewness in the inertial sublayer of turbulent wall flows Open
We provide empirical evidence that within the inertial sub layer of adiabatic turbulent flows over smooth walls, the skewness of the vertical velocity component $Sk_w$ displays universal behaviour, being constant and constrained within the…
View article: Stochastic modelling of the instantaneous velocity profile in rough-wall turbulent boundary layers
Stochastic modelling of the instantaneous velocity profile in rough-wall turbulent boundary layers Open
The statistical properties of uniform momentum zones (UMZs) are extracted from laboratory and field measurements in rough wall turbulent boundary layers to formulate a set of stochastic models for the simulation of instantaneous velocity p…
View article: Flow statistics from large-eddy simulations of convective atmospheric boundary layers
Flow statistics from large-eddy simulations of convective atmospheric boundary layers Open
The present dataset includes time-averaged flow statistics from large-eddy simulations (LES) of the convective atmospheric boundary layer (CBL). The seven simulation cases span weak to moderate convection on a numerical grid with 1024x1024…
View article: Flow statistics from large-eddy simulations of convective atmospheric boundary layers
Flow statistics from large-eddy simulations of convective atmospheric boundary layers Open
The present dataset includes time-averaged flow statistics from large-eddy simulations (LES) of the convective atmospheric boundary layer (CBL). The seven simulation cases span weak to moderate convection on a numerical grid with 1024x1024…
View article: On the departure from Monin-Obukhov surface similarity and transition to the convective mixed layer
On the departure from Monin-Obukhov surface similarity and transition to the convective mixed layer Open
Large-eddy simulations are used to evaluate mean profile similarity in the convective boundary layer (CBL). Particular care is taken regarding the grid sensitivity of the profiles and the mitigation of inertial oscillations in the simulati…
View article: Evidence of Mixed Scaling for Mean Profile Similarity in the Stable Atmospheric Surface Layer
Evidence of Mixed Scaling for Mean Profile Similarity in the Stable Atmospheric Surface Layer Open
A new mixed scaling parameter Z = z /( Lh ) 1/2 is proposed for similarity in the stable atmospheric surface layer, where z is the height, L is the Obukhov length, and h is the boundary layer depth. In comparison with the parameter ζ = z /…
View article: Turbulence Organization and Mean Profile Shapes in the Stably Stratified Boundary Layer: Zones of Uniform Momentum and Air Temperature
Turbulence Organization and Mean Profile Shapes in the Stably Stratified Boundary Layer: Zones of Uniform Momentum and Air Temperature Open
A persistent spatial organization of eddies is identified in the lowest portion of the stably stratified planetary boundary layer. The analysis uses flow realizations from published large-eddy simulations (Sullivan et al. in J Atmos Sci 73…
View article: Evidence of mixed scaling for mean profile similarity in the stable atmospheric surface layer
Evidence of mixed scaling for mean profile similarity in the stable atmospheric surface layer Open
A new mixed scaling parameter $Z=z/\sqrt{Lh}$ is proposed for similarity in the stable atmospheric surface layer, where $z$ is the height, $L$ is the Obukhov length, and $h$ is the boundary layer depth. Compared to the parameter $ζ= z/L$ f…
View article: Turbulence organization and mean profile shapes in the stably stratified boundary layer: zones of uniform momentum and air temperature
Turbulence organization and mean profile shapes in the stably stratified boundary layer: zones of uniform momentum and air temperature Open
A persistent spatial organization of eddies is identified in the lowest portion of the stably-stratified planetary boundary layer. The analysis uses flow realizations from published large-eddy simulations (Sullivan et al., J Atmos Sci 73(4…
View article: Self-similar geometries within the inertial subrange of scales in boundary layer turbulence
Self-similar geometries within the inertial subrange of scales in boundary layer turbulence Open
The inertial subrange of turbulent scales is commonly reflected by a power law signature in ensemble statistics such as the energy spectrum and structure functions – both in theory and from observations. Despite promising findings on the t…
View article: Effect of finite Reynolds number on self-similar crossing statistics and fractal measurements in turbulence
Effect of finite Reynolds number on self-similar crossing statistics and fractal measurements in turbulence Open
Stochastic simulations are used to create synthetic one-dimensional telegraph\napproximation (TA) signals based on turbulent zero crossings, where the\ninterval between crossings is governed by a power law probability distribution\nwith ex…
View article: Relating exponents of truncated power laws for self-similar signals
Relating exponents of truncated power laws for self-similar signals Open
Stochastic simulations are conducted to evaluate relations between statistics for processes governed by a power law probability distribution with exponent $\alpha$. The power law exponent is determined for statistics of simulated signals, …
View article: Prograde vortices, internal shear layers and the Taylor microscale in high-Reynolds-number turbulent boundary layers
Prograde vortices, internal shear layers and the Taylor microscale in high-Reynolds-number turbulent boundary layers Open
View article: Aerodynamics of Highway Sign Structures: From Laboratory Tests and Field Monitoring to Structural Design Guidelines
Aerodynamics of Highway Sign Structures: From Laboratory Tests and Field Monitoring to Structural Design Guidelines Open
Field- and model-scale experiments were conducted to quantitatively assess the effects of wind loading on Rural Intersection Conflict Warning System (RICWS) highway sign structures. A field-scale RICWS was instrumented with acceleration an…
View article: Understanding and Mitigating the Dynamic Behavior of RICWS and DMS under Wind Loading
Understanding and Mitigating the Dynamic Behavior of RICWS and DMS under Wind Loading Open
Dynamic Messaging Signs (DMS) and Rural Intersection Conflict Warning Signs (RICWS) are roadside signs that feature much larger and heavier signs than are typically placed on their respective support systems. The excess weight and size of …
View article: A Mixed Length Scale Model for Migrating Fluvial Bedforms
A Mixed Length Scale Model for Migrating Fluvial Bedforms Open
With the expansion of hydropower, in‐stream converters, flood‐protection infrastructures, and growing concerns on deltas fragile ecosystems, there is a pressing need to evaluate and monitor bedform sediment mass flux. It is critical to est…
View article: Organization And Scaling Of Coherent Structures In The Outer Region Of High-Reynolds-Number Turbulent Boundary Layers
Organization And Scaling Of Coherent Structures In The Outer Region Of High-Reynolds-Number Turbulent Boundary Layers Open
University of Minnesota Ph.D. dissertation. May 2020. Major: Civil Engineering. Advisor: Michele Guala. 1 computer file (PDF); x, 121 pages.
View article: On the mixing length eddies and logarithmic mean velocity profile in wall turbulence
On the mixing length eddies and logarithmic mean velocity profile in wall turbulence Open
Since the introduction of the logarithmic law of the wall more than 80 years\nago, the equation for the mean velocity profile in turbulent boundary layers\nhas been widely applied to model near-surface processes and parameterise\nsurface d…
View article: The spatial structure of the logarithmic region in very-high-Reynolds-number rough wall turbulent boundary layers
The spatial structure of the logarithmic region in very-high-Reynolds-number rough wall turbulent boundary layers Open
Using super-large-scale particle image velocimetry (SLPIV), we investigate the spatial structure of the near-wall region in the fully rough atmospheric surface layer with Reynolds number $Re_{\unicode[STIX]{x1D70F}}\sim O(10^{6})$ . The fi…
View article: Particle image velocimetry measurements of smooth- and rough-wall turbulence from the SAFL Atmospheric Boundary Layer wind tunnel
Particle image velocimetry measurements of smooth- and rough-wall turbulence from the SAFL Atmospheric Boundary Layer wind tunnel Open
Wall-bounded turbulent flows under smooth- and rough-wall surface conditions were measured using particle image velocimetry (PIV) in the Atmospheric Boundary Layer Wind Tunnel at St. Anthony Falls Laboratory (SAFL), University of Minnesota…
View article: The spectral signature of wind turbine wake meandering: A wind tunnel and field‐scale study
The spectral signature of wind turbine wake meandering: A wind tunnel and field‐scale study Open
Field‐scale and wind tunnel experiments were conducted in the 2 D to 6 D turbine wake region to investigate the effect of geometric and Reynolds number scaling on wake meandering. Five field deployments took place: 4 in the wake of a singl…
View article: Predictive model for local scour downstream of hydrokinetic turbines in erodible channels
Predictive model for local scour downstream of hydrokinetic turbines in erodible channels Open
A modeling framework is derived to predict the scour induced by marine hydrokinetic turbines installed on fluvial or tidal erodible bed surfaces. Following recent advances in bridge scour formulation, the phenomenological theory of turbule…