Abstract Laboratory experiments have yielded evidence suggestive of large-scale meandering motions in the wake an axial flow hydrokinetic turbine a turbulent open channel (Chamorro et al. , J. Fluid Mech. vol. 716, 2013, pp. 658–670). We carry out large-eddy simulation (LES) experimental to investigate structure turbulence and elucidate mechanism that gives rise meandering. All geometrical details are taken into account using curvilinear immersed boundary LES method with wall modelling (Kang...

We study the turbine spacing effects in infinite, aligned wind-turbine arrays using large-eddy simulation (LES) with wind rotors parameterized as actuator disks. A series of simulations is carried out to systematically investigate different streamwise and spanwise spacings on array power output turbulence intensities. show that for same density, increasing more beneficial than spacing. Larger increases extraction lowers intensity at each efficiently when increased. The reason farm...

A numerical model based upon a second-order upwind finite volume method on unstructured triangular grids is developed for solving shallow water equations. The HLL approximate Riemann solver used the computation of inviscid flux functions, which makes it possible to handle discontinuous solutions. multidimensional slope-limiting technique employed achieve spatial accuracy and prevent spurious oscillations. To alleviate problems associated with instabilities due small depths near wet/dry...

[1] Large-eddy simulation of turbulent flow through a natural-like meandering channel with pool-riffle sequences installed in the St. Anthony Falls Laboratory Outdoor StreamLab is carried out to elucidate hydrodynamics at bankfull condition. It shown that shallow riffle dominated by presence large-scale roughness elements enhance mixing; increase turbulence anisotropy; and induce multiple, streamwise secondary cells driven anisotropy. The pool, on other hand, formation interaction center...

Abstract Flume experiments were conducted to investigate the three‐dimensional flow structure and turbulent mechanisms around a nonsubmerged, sidewall‐attached rectangular spur dike with low length‐to‐depth ratio. Velocity measurements show that wake of in middepth region consists single, large recirculation zone, while near‐bed is composed horizontal zone corner vortex its axis perpendicular flume sidewalls. A horseshoe system observed front found interact downstream which results increase...

The Coronavirus disease outbreak of 2019 has been causing significant loss life and unprecedented economical throughout the world. Social distancing face masks are widely recommended around globe in order to protect others prevent spread virus through breathing, coughing, sneezing. To expand scientific underpinnings such recommendations, we carry out high-fidelity computational fluid dynamics simulations resolution realism elucidate underlying physics saliva particulate transport during...

This paper presents a systematic numerical investigation to study the effects of inlet turbulent boundary conditions on coupled hydrodynamics and morphodynamics computations natural river, Feather River, located in northern California. A flow (Eulerian) sediment dynamics framework is employed simulate fully hydro-morphodynamics 600-m-long reach river which there are several bridge foundations. The modeled using large-eddy simulation (LES). considered consist (1) uniform flow, (2)...

In meandering rivers, interactions between flow, sediment transport, and bed topography affect diverse processes, including bedform development channel migration. Predicting how these the spatial patterns magnitudes of deformation in rivers is essential for various river engineering geoscience problems. Computational fluid dynamics simulations can predict morphodynamics at fine temporal scales but have traditionally been challenged by large scale natural rivers. We conducted coupled...

We present high-fidelity numerical simulations of expiratory biosol transport during normal breathing under indoor, stagnant air conditions with and without a facile mask. investigate mask efficacy to suppress the spread saliva particles that is underpinnings existing social distancing recommendations. The incorporate effect human anatomy consider spectrum particulate sizes range from 0.1 10 μm while also accounting for their evaporation. elucidate vorticity dynamics show mask, particulates...

Summary An improved near‐wall modeling for large‐eddy simulation using the immersed boundary method is proposed. It shown in this study that existing (IB) methods imposes velocity condition at IB node not sufficient to enforce a correct wall shear stress node. A new through modification of subgrid scale‐eddy viscosity In method, eddy modified such viscous flux face adjacent correctly approximates total stress. The applied simulate fully developed turbulent flows plane channel and circular...

Archer fish jumping for prey capture are capable of achieving accelerations that can reach 12 times gravitational from a stationary start at the free surface. This behavior is associated with nontrivial production hydrodynamic thrust. In this work, we numerically investigate and aerodynamic performance smallscale archer (Toxotes microlepis) to elucidate propulsive mechanisms contribute rapid acceleration considerable jump accuracy. We conduct high-fidelity, two-phase flow, large-eddy...

Abstract Prediction of statistical properties the turbulent flow in large‐scale rivers is essential for river analysis. The large‐eddy simulation (LES) provides a powerful tool such predictions; however, it requires very long sampling time and demands significant computing power to calculate turbulence statistics riverine flows. In this study, we developed encoder‐decoder convolutional neural networks (CNNs) predict first‐ second‐order meandering using instantaneous LES results. We train...

The predictive capabilities of an isotropic, eddy viscosity turbulence model for closing the unsteady Reynolds‐averaged Navier‐Stokes (RANS) equations are systematically investigated by simulating turbulent flow through a field‐scale meandering channel and comparing computed results with large‐eddy simulation (LES) same recently reported Kang Sotiropoulos (2011). To facilitate comparison two models, both RANS LES carried on exactly grid numerical method. comparisons show that while captures...

Abstract We carry out numerical simulations to investigate the vortex dynamics of laminar, impulsively driven flows through inclined nozzles in a piston–cylinder apparatus. Our are motivated by need provide complete description intricate vortical structures and governing mechanisms emerging such as documented experiments Webster & Longmire ( Phys. Fluids , vol. 10, 1998, pp. 400–416) Troolin Exp. 48, 2010, 409–420). show that flow is dominated interaction two main structures: primary...