Load balance and parallel I/O: Optimising COSA for large simulations

Jackson, Adrian; Campobasso, M. Sergio; Drofelnik, Jernej

doi:10.1016/j.compfluid.2018.03.007

Cited by 7 publications

(7 citation statements)

References 11 publications

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“…The code also features an efficient harmonic balance solver for the rapid solution of wind turbine unsteady periodic flows, which has been shown to reduce by up to 50 times the runtime for the NS CFD analysis of fixedbottom HAWT rotors with respect to the conventional time-domain NS method [6,19,28]. COSA has a highly efficient parallelization of both its computing and IO sections [29], and distributed-memory (MPI) simulations have been efficiently…”

Section: Space Discretization and Numerical Integrationmentioning

confidence: 99%

Computational Fluid Dynamics Analysis of Floating Offshore Wind Turbines in Severe Pitching Conditions

Ortolani

Persico

Drofelnik

et al. 2020

Journal of Engineering for Gas Turbines and Power

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The unsteady aerodynamics of floating offshore wind turbines is more complex than that of fixed--bottom turbines, and the uncertainty of low-fidelity predictions is higher for floating turbines. Navier--Stokes CFD can improve the understanding of rotor and wake aerodynamics of floating turbines, and help improving lower-fidelity models. Here, blade--resolved simulations of the compressible CFD COSA code and the incompressible CFD FLUENT code are used to investigate the unsteady flow of the NREL 5 MW rotor subjected to prescribed harmonic pitching past the tower base. CFD results are compared to predictions of the FAST wind turbine code, which uses blade element momentum theory. The rotor power and loads in fixed--tower mode predicted by both CFD codes and FAST are in very good agreement. For the floating turbine, all predicted periodic profiles of rotor power and thrust are qualitatively similar, but the power peaks of both CFD predictions are significantly higher than those of FAST. Cross--comparisons of the COSA and FLUENT CFD profiles of blade static pressure also highlights significant compressible flow effects on rotor power and loads. The CFD analyses of the downstream rotor flow field reveals wake features unique to pitching turbines, primarily the space- and time--dependence of the wake generation, highlighted by the intermittency of the tip vortex shedding. The FLUENT pitching rotor analyses use a novel user--defined function, enforcing an additional rigid body motion of the grid conformal to the tower motion, providing new functionalities for floating turbine analyses.

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Section: Space Discretization and Numerical Integrationmentioning

confidence: 99%

Computational Fluid Dynamics Analysis of Floating Offshore Wind Turbines in Severe Pitching Conditions

Ortolani

Persico

Drofelnik

et al. 2020

Journal of Engineering for Gas Turbines and Power

Self Cite

View full text Add to dashboard Cite

show abstract

“…The code also features an efficient harmonic balance solver for the rapid solution of wind turbine unsteady periodic flows, which has been shown to reduce by up to 50 times the runtime for the NS CFD analysis of fixed-bottom HAWT rotors with respect to the conventional time-domain NS method [6,19,28]. COSA has a highly efficient parallelization of both its computing and IO sections [29], and distributed-memory (MPI) simulations have been efficiently run with up to 16,000 cluster cores [25].…”

Section: Compressible Cfd Solver Space Discretization and Numerical Integrationmentioning

confidence: 99%

High-Fidelity Calculation of Floating Offshore Wind Turbines Under Pitching Motion

Ortolani

Persico

Drofelnik

et al. 2020

Volume 12: Wind Energy

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The unsteady aerodynamics of floating offshore wind turbine (FOWT) rotors is more complex than that of fixed–bottom turbine rotors, and the uncertainty of low-fidelity aerodynamic predictions, such as those of the blade element momentum theory (BEMT) codes, is higher for the former rotors. Navier-Stokes CFD can improve the understanding of FOWT rotor and wake aerodynamics, and help improve lower-fidelity models. To highlight this potential, blade–resolved analyses of the in-house compressible CFD COSA code and the commercial incompressible CFD code FLUENT were used to investigate the unsteady flow of the NREL 5 MW rotor subjected to prescribed harmonic pitching past the tower base. CFD results were compared to the predictions of the FAST wind turbine code, using BEMT for rotor aerodynamics. Improved tuning of the COSA numerical set-up enabled close matching of the FAST rotor power and loads in fixed–tower mode, and high resolution of the near field wake dynamics; similar agreement levels were obtained with the FLUENT simulations. A novel user-defined function approach, enforcing an additional rigid body motion of the rotor grid conformal to the tower motion, enabled the FLUENT FOWT rotor simulations of this study, and provided new general-purpose FLUENT functionalities for FOWT analyses. All predicted periodic patterns of rotor power and thrust were found to be qualitatively similar, but the power peaks of both CFD predictions were significantly higher than those of FAST. Inspection of the CFD profiles of blade static pressure highlighted and quantified significant compressible flow effects on FOWT rotor power and loads. The blade–resolved analyses of the rotor downstream flow field revealed wake features unique to pitching turbine rotors, primarily the space- and time–dependence of the wake generation, highlighted by the intermittency of the tip vortex shedding.

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“…COSA has been shown to exhibit good parallel scaling to large numbers of MPI processes with a sufficiently large test case [14]. running the simulation, meaning it is not possible to run using a single process or node from the test systems we had access to.…”

Section: Hpcgmentioning

confidence: 99%

Evaluating the Arm Ecosystem for High Performance Computing

Jackson

Turner

Weiland

et al. 2019

Proceedings of the Platform for Advanced Scientific Computing Conference

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In recent years, Arm-based processors have arrived on the HPC scene, offering an alternative the existing status quo, which was largely dominated by x86 processors. In this paper, we evaluate the Arm ecosystem, both the hardware offering and the software stack that is available to users, by benchmarking a production HPC platform that uses Marvell's ThunderX2 processors. We investigate the performance of complex scientific applications across multiple nodes, and we also assess the maturity of the software stack and the ease of use from a users' perspective. This papers finds that the performance across our benchmarking applications is generally as good as, or better, than that of well-established platforms, and we can conclude from our experience that there are no major hurdles that might hinder wider adoption of this ecosystem within the HPC community.

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Load balance and parallel I/O: Optimising COSA for large simulations

Cited by 7 publications

References 11 publications

Computational Fluid Dynamics Analysis of Floating Offshore Wind Turbines in Severe Pitching Conditions

Computational Fluid Dynamics Analysis of Floating Offshore Wind Turbines in Severe Pitching Conditions

High-Fidelity Calculation of Floating Offshore Wind Turbines Under Pitching Motion

Evaluating the Arm Ecosystem for High Performance Computing

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