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Rao, P.V. (author), Dwight, R.P. (author), Singh, D. (author), Maruhashi, J. (author), Dedoussi, I.C. (author), Grewe, V. (author), Frömming, Christine (author)While efforts have been made to curb CO2 emissions from aviation, the more uncertain non-CO2 effects that contribute about two-thirds to the warming in terms of radiative forcing (RF), still require attention. The most important non-CO2 effects include persistent line-shaped contrails, contrail-induced cirrus clouds and nitrogen oxide (NOx)...conference paper 2023
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Grabe, Cornelia (author), Jäckel, Florian (author), Khurana, Parv (author), Dwight, R.P. (author)Purpose: This paper aims to improve Reynolds-averaged Navier Stokes (RANS) turbulence models using a data-driven approach based on machine learning (ML). A special focus is put on determining the optimal input features used for the ML model. Design/methodology/approach: The field inversion and machine learning (FIML) approach is applied to...journal article 2023
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- Singh, D. (author), Dwight, R.P. (author), Viré, A.C. (author) poster 2022
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Singh, D. (author), Dwight, R.P. (author), Laugesen, Kasper (author), Beaudet, Laurent (author), Viré, A.C. (author)Heteroscedastic Gaussian process regression, based on the concept of chained Gaussian processes, is used to build surrogates to predict site-specific loads on an offshore wind turbine. Stochasticity in the inflow turbulence and irregular waves results in load responses that are best represented as random variables rather than deterministic...journal article 2022
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Steiner, J. (author), Dwight, R.P. (author), Viré, A.C. (author)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...journal article 2022
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Xu, R. (author), Zhou, Xu Hui (author), Han, Jiequn (author), Dwight, R.P. (author), Xiao, Heng (author)In fluid dynamics, constitutive models are often used to describe the unresolved turbulence and to close the Reynolds averaged Navier–Stokes (RANS) equations. Traditional PDE-based constitutive models are usually too rigid to calibrate with a large set of high-fidelity data. Moreover, commonly used turbulence models are based on the weak...journal article 2022
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Steiner, J. (author), Viré, A.C. (author), Dwight, R.P. (author)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...journal article 2022
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Huijing, Jasper P. (author), Dwight, R.P. (author), Schmelzer, M. (author)In this short note we apply the recently proposed data-driven RANS closure modelling framework of Schmelzer et al.(2020) to fully three-dimensional, high Reynolds number flows: namely wall-mounted cubes and cuboids at Re=40,000, and a cylinder at Re=140,000. For each flow, a new RANS closure is generated using sparse symbolic regression based...journal article 2021
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Zhang, Yu (author), Dwight, R.P. (author), Schmelzer, M. (author), Gómez, Javier F. (author), Han, Zhong hua (author), Hickel, S. (author)Multi-fidelity optimization methods promise a high-fidelity optimum at a cost only slightly greater than a low-fidelity optimization. This promise is seldom achieved in practice, due to the requirement that low- and high-fidelity models correlate well. In this article, we propose an efficient bi-fidelity shape optimization method for...journal article 2021
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Steiner, J. (author), Dwight, R.P. (author), Viré, A.C. (author)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...journal article 2020
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Luan, Yuyang (author), Dwight, R.P. (author)Simulating wind-turbines in Reynolds-averaged Navier-Stokes (RANS) codes is highly challenging, at least partly due to the importance of turbulence anisotropy in the evolution of the wake. We present a preliminary investigation into the role of anisotropy in RANS simulations of vertical-axis turbines, by comparison with LES. Firstly an LES...journal article 2020
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Kaandorp, Mikael L.A. (author), Dwight, R.P. (author)A novel machine learning algorithm is presented, serving as a data-driven turbulence modeling tool for Reynolds Averaged Navier-Stokes (RANS) simulations. This machine learning algorithm, called the Tensor Basis Random Forest (TBRF), is used to predict the Reynolds-stress anisotropy tensor, while guaranteeing Galilean invariance by making use...journal article 2020
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Sarma, R. (author), Dwight, R.P. (author), Viré, A.C. (author)Downwind wind turbine blades are subjected to tower wake forcing at every rotation, which can lead to structural fatigue. Accurate characterisation of the unsteady aeroelastic forces in the blade design phase requires detailed representation of the aerodynamics, leading to computationally expensive simulation codes, which lead to intractable...journal article 2020
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Schmelzer, M. (author), Dwight, R.P. (author), Cinnella, Paola (author)In this work recent advancements are presented in utilising deterministic symbolic regression to infer algebraic models for turbulent stress-strain relation with sparsity-promoting regression techniques. The goal is to build a functional expression from a set of candidate functions in order to represent the target data most accurately....conference paper 2020
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Steiner, J. (author), Viré, A.C. (author), Benetti, F. (author), Timmer, W.A. (author), Dwight, R.P. (author)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...journal article 2020
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Belligoli, Z. (author), Dwight, R.P. (author), Eitelberg, G. (author), Raghunathan Srikumar, S.K. (author), Engler Faleiros, D. (author), van Nesselrooij, M. (author), van Campenhout, O.W.G. (author)An anti-fairing is a concave deformation of the wall around a wing-body junction that can decrease the aerodynamic drag through the activation of a propulsive force generated by the interaction of the curved concave shape and the high-pressure region in proximity of the wing leading-edge. Although this mechanism is well understood, the...conference paper 2020
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Schmelzer, M. (author), Dwight, R.P. (author), Cinnella, Paola (author)A novel deterministic symbolic regression method SpaRTA (Sparse Regression of Turbulent Stress Anisotropy) is introduced to infer algebraic stress models for the closure of RANS equations directly from high-fidelity LES or DNS data. The models are written as tensor polynomials and are built from a library of candidate functions. The machine...journal article 2019
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Belligoli, Z. (author), Dwight, R.P. (author), Eitelberg, G. (author)Despite a steady decrease in the overall usage of wind tunnels due to the increasing reliability and speed of computational fluid dynamics (CFD), ground testing remains a fundamental part of the development of an air vehicle. In this context, one of the new trends is represented by data assimilation (DA), whereby experimental and numerical...conference paper 2019
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Schwarz, Alexander (author), Dwight, R.P. (author)We investigate theoretically and numerically the use of the least-squares finite-element method (LSFEM) to approach data-assimilation problems for the steady-state, incompressible Navier-Stokes equations. Our LSFEM discretization is based on a stress-velocity-pressure (S-V-P) first-order formulation, using discrete counterparts of the Sobolev...journal article 2018
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Belligoli, Z. (author), Dwight, R.P. (author), Kok, G. J.P. (author), Lucas, P. (author)This paper presents an approach for updating the epistemic uncertainty of ultrasonic flow meter measurements under non-ideal flow conditions. Instead of re-calibrating the instrument to correct its behavior in these difficult working conditions, a Bayesian calibration of a computer model of the real process is used. The numerical model is...journal article 2017