Isolates of `Candidatus Nostocoida limicola¿ Blackall et al. 2000 should be described as three novel species of the genus Tetrasphaera, as Tetrasphaera jenkinsii sp. nov., Tetrasphaera vanveenii sp. nov. and Tetrasphaera veronensis sp. nov

A quantitative comparison study of a contextual and cognitive model of Air Traffic Controller workload

Up to this point, research into Air Traffic Controller workload has primarily focused on a number of discrete areas. However, it is widely recognized that different components from these respective fields all contribute to the workload an Air Traffic Controller experiences. Hence, this study has tried to bridge this gap by quantitatively...

The influence of freeze-thaw cycles on the shear strength of Illite clay

Thermo-active structures, such as energy piles, are used to store and extract heat energy from soil. In areas with seasonal freezing and thawing, such infrastructure is subjected to changes in the soil structure and, consequently, the soil strength. This research investigated the influence of repeated freeze-thaw (FT) cycles and different...

The influence of freeze–thaw cycles on the shear strength of illite clay

Geo-energy infrastructure, such as ground source heat systems (thermo-active structures), induce thermal cycles that can result in changes of the bearing capacity of soil by changing, for example, the void ratio, soil structure, unit weight and hydraulic conductivity. The influence of repeated freeze/thaw (FT) cycles and different freezing rates...

High Fidelity Aeroelastic Analysis of a Membrane Wing

A Remarkable Integer Sequence Related to π and √2

We prove that five ways to define entry A086377 in the OEIS do lead to the sameinteger sequence.<br/>Dedicated to Jeff Shallit on the occasion of his 60th birthday

Towards the CSM-CFD modelling of membrane wings at high Reynolds numbers

The field of Airborne Wind Energy is concerned with harvesting high-altitude wind power; the corresponding group in Delft, in particular, is investigating the suitability of a kite for this purpose. Due to the high complexity that such a system ensues, it is of interest to have a fundamental understanding of the critical aero-elastic modes of...

Inclusion of Building-Resolving Capabilities Into the FastEddy® GPU-LES Model Using an Immersed Body Force Method

As a first step toward achieving full physics urban weather simulation capabilities within the resident-GPU large-eddy simulation (LES) FastEddy® model, we have implemented and verified/validated a method for explicit representation of building effects. Herein, we extend the immersed body force method (IBFM) from Chan and Leach (2007, https:/...

Variations in storm-induced bed level dynamics across intertidal flats

Hydrodynamic forces on intertidal flats vary over a range of temporal and spatial scales. These spatiotemporal inhomogeneities have implications for intertidal flat morphodynamics and ecology. We determine whether storm events are capable of altering the long-term morphological evolution of intertidal flats, and unravel the contributions of...

Parametric slat design study for thick-base airfoils at high Reynolds numbers

Standard passive aerodynamic flow control devices such as vortex generators and gurney flaps have a working principle that is well understood. They increase the stall angle and the lift below stall and are mainly applied at the inboard part of wind turbine blades. However, the potential of applying a rigidly fixed leading-edge slat element at...

Data-driven turbulence modeling for wind turbine wakes under neutral conditions

Currently, the state of the art in wind farm flow physics modeling are Large Eddy Simulations (LES) which resolve a large part of the spectra of the turbulent fluctuations. But this type of model requires extensive computational resources. One wind speed and direction simulation of the Lillgrund wind farm can take between 160k and 3000k...

Mapping the aerodynamic roughness of the Greenland Ice Sheet surface using ICESat-2: Evaluation over the K-transect

The aerodynamic roughness of heat, moisture, and momentum of a natural surface are important parameters in atmospheric models, as they co-determine the intensity of turbulent transfer between the atmosphere and the surface. Unfortunately this parameter is often poorly known, especially in remote areas where neither high-resolution elevation...

Data-driven RANS closures for wind turbine wakes under neutral conditions

The state-of-the-art in wind-farm flow-physics modeling is Large Eddy Simulation (LES) which makes accurate predictions of most relevant physics, but requires extensive computational resources. The next-fidelity model types are Reynolds-Averaged Navier–Stokes (RANS) which are two orders of magnitude cheaper, but resolve only mean quantities...

Classifying Regions of High Model Error Within a Data-Driven RANS Closure: Application to Wind Turbine Wakes

Data-driven Reynolds-averaged Navier–Stokes (RANS) turbulence closures are increasing seen as a viable alternative to general-purpose RANS closures, when LES reference data is available—also in wind-energy. Parsimonious closures with few, simple terms have advantages in terms of stability, interpret-ability, and execution speed. However...

Experimental study of the effect of a slat on the aerodynamic performance of a thick base airfoil

There is continuous effort to try and improve the aerodynamic performance of wind turbine blades. This experimental study focusses on the addition of a passive slat on a thick airfoil typically used in the inboard part of commercial wind turbine blades. Nine different slat configurations are considered, with both a clean and tripped main airfoil...

Towards a Multivariate Spline-Based qLPV Flight Dynamics Model of Tiltrotor Aircraft

Towards data-driven turbulence modeling for wind turbine wakes

The Dutch energy strategy expects renewable energy sources like wind and solar to provide around 70% of the yearly electricity by 2030. In order to achieve these targets, models that efficiently and accurately capture the flow around wind turbines would be immensely helpful for both planning and operation of wind farms.<br/><br/>For wind turbine...