Hydrodynamic loadings on a horizontal axis tidal turbine prototype

Ouro, Pablo; Harrold, Magnus; Stoesser, Thorsten; Bromley, Peter T.

doi:10.1016/j.jfluidstructs.2017.03.009

Cited by 74 publications

(63 citation statements)

References 48 publications

(61 reference statements)

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“…The in-house HYDRO3D LES code is used to solve the filtered Navier-Stokes equations for an unsteady, incompressible, viscous flow (Bomminayuni & Stoesser, 2011;Fraga, Stoesser, Lai, & Socolofsky, 2016;Kara, Stoesser, & Sturm, 2012;Kim, Kim, & Stoesser, 2013;Ouro, Harrold, Stoesser, & Bromley, 2017;Stoesser, 2010;Stoesser, McSherry, & Fraga, 2015). LES is an eddy-resolving technique in which the energetic portion of the flow is simulated directly and only the small-scale turbulence is modelled (Stoesser, 2014), and is therefore capable of explicitly predicting turbulence and unsteadiness in flows of engineering importance (Koken & Constantinescu, 2009;McCoy, Constantinescu, & Weber, 2007).…”

Section: Numerical Framework and Computational Considerationsmentioning

confidence: 99%

Free surface flow over square bars at intermediate relative submergence

McSherry

Chua

Stoesser

et al. 2018

Journal of Hydraulic Research

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Results from large-eddy simulations and complementary flume experiments of turbulent open channel flows over bed-mounted square bars at intermediate submergence are presented. Scenarios with two bar spacings, corresponding to transitional and k-type roughness, and three flow rates, are investigated. Good agreement is observed between the simulations and the experiments in terms of mean free surface elevations and mean streamwise velocities. Contours of simulated time-averaged streamwise, streamfunction and turbulent kinetic energy are presented and these reveal the effect of the roughness geometry on the water surface response. The analysis of the vertical distribution of the streamwise velocity shows that in the lowest submergence cases no logarithmic layer is present, whereas in the higher submergence cases some evidence of such a layer is observed. For several of the flows moderate to significant water surface deformations are observed, including weak and/or undular hydraulic jumps which affect significantly to the overall streamwise momentum balance. Reynolds shear stress, form-induced stress and form drag are analysed with reference to the momentum balance to assess their contributions to the total hydraulic resistance of these flows. The results show that form-induced stresses are dominant at the water surface and can contribute significantly to the overall drag, but the total resistance in all cases is dominated by form drag due to the presence of the bars.

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Section: Numerical Framework and Computational Considerationsmentioning

confidence: 99%

Free surface flow over square bars at intermediate relative submergence

McSherry

Chua

Stoesser

et al. 2018

Journal of Hydraulic Research

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“…In this study the method of large‐eddy simulation (LES), using the code Hydro3D, an eddy‐resolving numerical method, is used for the overlying water. Hydro3D has been validated and applied to several flows of similar complexity to the one reported here (Fang et al, ; Liu et al, ; Ouro et al, ; Ouro & Stoesser, ). The code is based on finite differences on a staggered Cartesian grid and solves the filtered Navier‐Stokes equations for incompressible, unsteady and viscous flow:

\frac{\partial u_{i}}{\partial x_{i}} = 0

\frac{\partial u_{i}}{\partial t} + \frac{\partial u_{i} u_{j}}{\partial x_{j}} = - \frac{1}{ρ} \frac{\partial p}{\partial x_{i}} + \frac{\partial ((), 2 ν S_{ij})}{\partial x_{j}} - \frac{\partial τ_{ij}}{\partial x_{j}}

where u i or u j is the resolved velocity vector ( i or j = 1, 2, and 3 represent x , y , and z axes directions, respectively); and similarly, x i represents the spatial vectors in the three directions; ρ is water density; p is the resolved pressure above hydrostatic pressure; ʋ = kinematic viscosity; and S ij is the strain‐rate tensor.…”

Section: Methodsmentioning

confidence: 92%

Role of Bioroughness, Bioirrigation, and Turbulence on Oxygen Dynamics at the Sediment‐Water Interface

Liu

Reible

Hussain

et al. 2019

Water Resources Research

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Models that have been developed to quantify the oxygen flux at the sediment‐water interface (SWI) generally do not explicitly consider the influence of bioroughness (mounds and burrows) and bioirrigation. We performed a numerical study of the influence of overlying water velocity, bioroughness, and bioirrigation on the oxygen flux across the SWI. We found that compared with a flat bed, bioroughness significantly increases O2 transport at the SWI as a result of enhanced turbulence and pressure differences across the roughness. Bioirrigation can also enhance O2 transport across the SWI by a factor of up to 10 when the roughness Reynolds number (Re*) is low, but the influence of bioirrigation decreases with increasing Re*. Burrows increase O2 penetration depth, and bioirrigation causes asymmetric distributions of O2 along burrows. Despite the complexity of O2 distribution in sediments, the net exchange across the SWI can be described by the relationship of O'Connor and Harvey (2008, https://doi.org/10.1029/2008WR007160) 0.25em()De/DmRe*Pe1.2=a=0.0005 when the shape is two‐dimensional or when the burrow density is low. When the burrow density is large, flow is three‐dimensional and flow interactions between burrows become important. Under these conditions the net exchange across the SWI increases by up to a factor of 4. A burrow number is introduced, Bu = [burrow density]1/2 [burrow height], to correct the coefficient in O'Connor and Harvey's relationship, that is, a = 0.005 for Bu < 0.05 and a = 0.02 for Bu ≫ 0.1.

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“…The weighted essentially nonoscillatory scheme offers both sufficient computational accuracy and necessary algorithm stability to prevent the occurrence of numerical oscillations upstream of sharp solid bodies. The subgrid stresses are computed with the WALE model proposed by Nicoud and Ducros () because it has proven great accuracy in previous LESs of flow past immersed bodies (Kara, Sturm, McSherry, et al, , Kara, Sturm, McSherry, Mulahasan, et al, ; Ouro & Stoesser, , ; Ouro et al, ). The force exerted from the no‐slip boundary condition of a submerged body, such as the plates in this study, is accounted for by employing a direct forcing immersed boundary method (IBM; Kara, Stoesser, McSherry, et al, ).…”

Section: Numerical Frameworkmentioning

confidence: 99%

LES of Flow Through and Around a Finite Patch of Thin Plates

Gong

Stoesser

Mao

et al. 2019

Water Resources Research

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Large eddy simulations (LESs) are performed for turbulent flow through and around a porous patch of thin vertical plates at a plate Reynolds number of Rep=5,800. The plates are arranged in a staggered pattern, presenting an elliptical planform and mimicking streamwise‐oriented blades of emergent vegetation. The immersed boundary method is employed to explicitly resolve the interaction between flow and plates. Three flow cases, each with a different number of plates within the same planform area, that is, different patch density, are studied. The Reynolds number based on freestream velocity and plate length is the same in all cases. Inspection of the distribution of velocity and vorticity in the horizontal plane reveals that downstream plates are significantly impacted by the wakes from upstream plates. It is therefore proposed that the plates can be divided into two groups based on the local flow characteristics, which are a function of position within the patch: a free group and a wake group. This classification is subsequently used in the quantitative analysis of boundary layer development and drag force at plate scale. The thickness and character of the simulated boundary layers on the plates differ significantly from predictions based on analytical or empirical relationships, which is due to wake effects and the finite length of the plates. The simulations demonstrate the so‐called sheltering effect; that is, the drag forces acting on downstream plates (in the wake group) are significantly lower than those acting on upstream plates, a result of the lower approach flow speed. Although the front‐area‐to‐lateral‐area ratio of the plates is low (1/40), pressure drag is observed to be larger than friction drag for each plate. The ratio of pressure drag to the total drag at patch scale shows only very little dependence on the plate density of the patch.

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Hydrodynamic loadings on a horizontal axis tidal turbine prototype

Cited by 74 publications

References 48 publications

Free surface flow over square bars at intermediate relative submergence

Free surface flow over square bars at intermediate relative submergence

Role of Bioroughness, Bioirrigation, and Turbulence on Oxygen Dynamics at the Sediment‐Water Interface

LES of Flow Through and Around a Finite Patch of Thin Plates

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