Xcompact3D: An open-source framework for solving turbulence problems on a Cartesian mesh

Bartholomew, Paul; Deskos, Georgios; Frantz, Ricardo André Schuh; Schuch, Felipe Nornberg; Lamballais, Éric; Laizet, Sylvain

doi:10.1016/j.softx.2020.100550

Cited by 56 publications

(34 citation statements)

References 50 publications

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“…Turbulence-resolving simulations of a single three-bladed scale turbine are carried out using the wind farm simulator WInc3D [6] which is part of the open-source framework of flow solvers XCompact3D [7].The simulations are based on the incompressible Navier-Stokes and temperature scalar transport equations, coupled through a gravitational term. These equations are solved with sixth-order finite-difference schemes on a Cartesian mesh while a conventional actuator line method is used to model the turbine via a forcing term added to the momentum equation.…”

Section: Methodsmentioning

confidence: 99%

Do ambient shear and thermal stratification impact wind turbine tip-vortex breakdown?

Hodgkin

Laizet

Deskos

2022

J. Phys.: Conf. Ser.

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Modern wind turbines experience uneven inflow conditions across the rotor, due to the ambient flow’s shear and thermal stratification. Such conditions alter the shape and length of turbine wakes and thus impact the loads and power generation of downstream turbines. To this end, understanding the spatial evolution of the individual wakes under different atmospheric conditions is key to controlling and optimising turbine arrays. With this numerical study we aim to obtain a better understanding of the fundamental physics governing the near-wake dynamics of wind turbines under shear and thermal stability, by examining their tip-vortex breakup mechanisms. Our approach considers scale-resolving simulations of a single turbine wake under a linear shear profile as well as the application of harmonic tip perturbations to trigger flow instabilities. For the subsequent analysis we use the proper orthogonal decomposition (POD) method to extract coherent structures from the flow, and we also calculate mean kinetic energy fluxes to quantify each coherent structure’s contribution to wake recovery. The wake’s helical spiral is found to hinder wake recovery for all studied ambient flow conditions, whereas the mutual inductance instability has positive MKE flux leading to an enhanced wake recovery. Finally, the ambient shear has the largest impact on the local MKE flux with respect to downstream location by changing the shape of the curve and location of extrema, whereas thermal stratification has only a minimal impact on the magnitude of the near-wake local MKE flux distribution.

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Section: Methodsmentioning

confidence: 99%

Do ambient shear and thermal stratification impact wind turbine tip-vortex breakdown?

Hodgkin

Laizet

Deskos

2022

J. Phys.: Conf. Ser.

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“…For time integration explicit third order Runge-Kutta and second order implicit Crank-Nicolson is used. Details regarding numerical schemes in Xcompact3d are given in [8].…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, it was extended by Forooghi et al [6] with the IBM based on the approach introduced by Goldstein [7] to allow for more complex geometries. Xcompact3d (Bartholomew et al [8]) is a DNS code based on high-order compact finite differences scheme, which approach the accuracy of spectral methods. The code features an IBM based on the polynomial reconstruction approach introduced by Gautier et al [9].…”

Section: Introductionmentioning

confidence: 99%

Comparison of Different Solvers and Geometry Representation Strategies for Dns of Rough Wall Channel Flow

Theobald¹,

Schäfer²,

Yang³

et al. 2021

14th WCCM-ECCOMAS Congress

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In the present study we investigate an incompressible turbulent channel flow with heat transfer at Re τ = 180 with a deterministic surface topography consisting of truncated cones. Two solvers for each of the two boundary handling strategies are considered. With Nek5000 and OpenFOAM the influence of the roughness elements is directly accounted for by an unstructured body fitted mesh, whereas Xcompact3d and SIMSON utilize the immersed boundary method (IBM) to deal with the 3D geometry. The main focus of this work is on an evaluation of the usability of the IBM and a comparison of the parallel performance of the different solvers. Since usability is an ambiguous definition, various quantities are compared: global statistics like Nusselt number and friction coefficient, one-dimensional wall-normal profiles for first and second order statistics, as well as three-dimensional averages over roughness sections. In addition, the computational effort for each method is documented.

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“…The simulations in this study are carried out within the open-source, turbulence simulation framework Xcompact3D 1 , designed for DNS and LES of incompressible and low-Mach number flows using a Cartesian mesh and high-order finite-difference schemes (Laizet and Lamballais, 2009;Laizet and Li, 2011;Bartholomew et al, 2020). The incompressible flow solver within Xcompact3D is called Incompact3d and is based on sixthorder compact finite-difference schemes (Laizet and Lamballais, 2009) for the spatialdiscretisation and a fractional-step method using a third-order explicit Adams-Bashforth method for the temporal integration (other time schemes are available, depending on the flow configuration).…”

Section: Flow Solvermentioning

confidence: 99%

High-fidelity simulations of gravity currents using a high-order finite-difference spectral vanishing viscosity approach

et al. 2021

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This numerical work investigates the potential of a high-order finite-difference spectral vanishing viscosity approach to simulate gravity currents at high Reynolds numbers. The method introduces targeted numerical dissipation at small scales through altering the discretisation of the second derivatives of the viscous terms in the incompressible Navier-Stokes equations to mimic the spectral vanishing viscosity (SVV) operator, originally designed for the regularisation of spectral element method (SEM) solutions of pure advection problems. Using a sixth-order accurate finite-difference scheme, the adoption of the SVV method is straightforward and comes with a negligible additional computational cost. In order to assess the ability of this high-order finite-difference spectral vanishing viscosity approach, we performed large-eddy simulations (LES) of a gravity current in a channelised lock-exchange set-up with our SVV model and with the well-known explicit static and dynamic Smagorinsky sub-grid scale (SGS) models. The obtained data are compared with a direct numerical simulation (DNS) based on more than 800 million mesh nodes, and with experimental measurements. A framework for the energy budget is introduced to investigate the behaviour of the gravity current. First, it is found that the DNS is in good agreement with the experimental data for the evolution of the front location and velocity field as well as for the stirring and mixing inside the gravity current. Secondly, the LES performed with less than 0.4% of the total number of mesh nodes compared to the DNS, can reproduce the main features of the gravity currents, with the SVV model yielding slightly more accurate results. It is also found that the dynamic Smagorinsky model performs better than its static version. For the present study, the static and dynamic Smagorinsky models are 1.8 and 2.5 times more expensive than the SVV model, because the latter does not require the calculation of explicit SGS terms in the Navier-Stokes equations nor spatial filtering operations.

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Xcompact3D: An open-source framework for solving turbulence problems on a Cartesian mesh

Cited by 56 publications

References 50 publications

Do ambient shear and thermal stratification impact wind turbine tip-vortex breakdown?

Do ambient shear and thermal stratification impact wind turbine tip-vortex breakdown?

Comparison of Different Solvers and Geometry Representation Strategies for Dns of Rough Wall Channel Flow

High-fidelity simulations of gravity currents using a high-order finite-difference spectral vanishing viscosity approach

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