Michael Sprague
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View article: Modeling the effects of active wake mixing on wake behavior through large-scale coherent structures
Modeling the effects of active wake mixing on wake behavior through large-scale coherent structures Open
The use of active wake mixing (AWM) to mitigate downstream turbine wakes has created new opportunities for reducing power losses in wind farms. However, many current analytical or semi-empirical wake models do not capture the flow instabil…
View article: AMR‐Wind: A Performance‐Portable, High‐Fidelity Flow Solver for Wind Farm Simulations
AMR‐Wind: A Performance‐Portable, High‐Fidelity Flow Solver for Wind Farm Simulations Open
We present AMR‐Wind, a verified and validated high‐fidelity computational‐fluid‐dynamics code for wind farm flows. AMR‐Wind is a block‐structured, adaptive‐mesh, incompressible‐flow solver that enables predictive simulations of the atmosph…
View article: Improved pressure-gradient sensor for the prediction of separation onset in RANS models
Improved pressure-gradient sensor for the prediction of separation onset in RANS models Open
Here, we improve upon two key aspects of the Menter shear stress transport (SST) turbulence model: (1) We propose a more robust adverse pressure gradient sensor based on the strength of the pressure gradient in the direction of the local m…
View article: Pressure-Gradient-Based RANS Model for Predicting Separation in Transitional and Turbulent Flows
Pressure-Gradient-Based RANS Model for Predicting Separation in Transitional and Turbulent Flows Open
Predicting flow separation poses a significant challenge for RANS models, particularly in transitional flows over airfoils. We propose a novel improvement to RANS models to predict incipient separation in both transitional and fully turbul…
View article: Modeling Turbulence in the Atmospheric Boundary Layer with Spectral Element and Finite Volume Methods
Modeling Turbulence in the Atmospheric Boundary Layer with Spectral Element and Finite Volume Methods Open
We present large-eddy-simulation (LES) modeling approaches for the simulation of atmospheric boundary layer turbulence that are of direct relevance to wind energy production. In this paper, we study a GABLS benchmark problem using high-ord…
View article: Three-Dimensional Aerodynamics and Vortex-Shedding Characteristics of Wind Turbine Airfoils over 360-Degree Angles of Attack
Three-Dimensional Aerodynamics and Vortex-Shedding Characteristics of Wind Turbine Airfoils over 360-Degree Angles of Attack Open
In this work, we present the first three-dimensional (3D) computational investigation of wind turbine airfoils over 360° angles of attack to predict unsteady aerodynamic loads and vortex-shedding characteristics. To this end, static–airfoi…
View article: Towards exascale for wind energy simulations
Towards exascale for wind energy simulations Open
We examine large-eddy-simulation modeling approaches and computational performance of two open-source computational fluid dynamics codes for the simulation of atmospheric boundary layer flows that are of direct relevance to wind energy pro…
View article: Improved pressure-gradient sensor for the prediction of separation onset in RANS models
Improved pressure-gradient sensor for the prediction of separation onset in RANS models Open
We improve upon two key aspects of the Menter shear stress transport (SST) turbulence model: (1) We propose a more robust adverse pressure gradient sensor based on the strength of the pressure gradient in the direction of the local mean fl…
View article: ExaWind: Open‐source CFD for hybrid‐RANS/LES geometry‐resolved wind turbine simulations in atmospheric flows
ExaWind: Open‐source CFD for hybrid‐RANS/LES geometry‐resolved wind turbine simulations in atmospheric flows Open
Predictive high‐fidelity modeling of wind turbines with computational fluid dynamics, wherein turbine geometry is resolved in an atmospheric boundary layer, is important to understanding complex flow accounting for design strategies and op…
View article: ExaWind at NREL: Upping the Ante
ExaWind at NREL: Upping the Ante Open
The objective of the ExaWind component of the Exascale Computing Project is to deliver many-turbine blade-resolved simulations in complex terrain. These simulations bring new challenges to both compute and analysis of the resulting data. I…
View article: Advanced Turbulence Models for Large-Scale Atmospheric Boundary Layer Flows
Advanced Turbulence Models for Large-Scale Atmospheric Boundary Layer Flows Open
We present high-fidelity large-eddy-simulation (LES) modeling approaches for the turbulent atmospheric boundary layer (ABL) flows. Wind energy is a prime example of an application driven by ABL. Generation of electrical energy from farms o…
View article: Mesh and model requirements for capturing deep-stall aerodynamics in low-Mach-number flows
Mesh and model requirements for capturing deep-stall aerodynamics in low-Mach-number flows Open
Here, this work presents a comprehensive computational fluid dynamics investigation of the effects of grid resolution and turbulence-model choice for capturing the unsteady three-dimensional aerodynamic performance of NACA 0012 and 0021 ai…
View article: Investigations of Farm-to-Farm Interactions and Blockage Effects from AWAKEN Using Large-Scale Numerical Simulations
Investigations of Farm-to-Farm Interactions and Blockage Effects from AWAKEN Using Large-Scale Numerical Simulations Open
A large-scale numerical computation of five wind farms was performed as a part of the American WAKE experimeNt (AWAKEN). This high-fidelity computation used the ExaWind/AMR-Wind LES solver to simulate a 100 km × 100 km domain containing 54…
View article: Computational Requirements in Clean Energy and Manufacturing: Summary report of the virtual workshop held on June 28-29, 2021
Computational Requirements in Clean Energy and Manufacturing: Summary report of the virtual workshop held on June 28-29, 2021 Open
On June 28–29, 2021, the US Department of Energy’s (DOE’s) Advanced Scientific Computing Research (ASCR) program in the Office of Science convened a workshop with the Energy Efficiency and Renew able Energy (EERE) program offices to assess…
View article: ExaWind: Then and Now
ExaWind: Then and Now Open
The scientific goal of the ExaWind project is to advance our fundamental understanding of the flow physics governing whole wind plant performance, including wake formation, complex terrain impacts, and turbine-turbine-interaction effects. …
View article: exawind-driver [SWR-23-10]
exawind-driver [SWR-23-10] Open
Exawind-driver is a C++ code that is part of the ExaWind software stack. It was designed to couple and drive hybrid-solver computational fluid dynamics (CFD) simulations where NREL's AMR-Wind (SWR-20-85) software and NREL's Nalu-Wind (SWR-…
View article: AEflow (Autoencoder fluid flow compression network) [SWR-22-29]
AEflow (Autoencoder fluid flow compression network) [SWR-22-29] Open
As the size of turbulent flow simulations continues to grow, in situ data compression is becoming increasingly important for visualization, analysis, and restart checkpointing. For these applications, single-pass compression techniques wit…
View article: FY2022 Q4: Demonstrate multi-turbine simulation with hybrid-structured/unstructured-moving-grid software stack running primarily on GPUs and propose improvements for successful KPP-2 [Poster]
FY2022 Q4: Demonstrate multi-turbine simulation with hybrid-structured/unstructured-moving-grid software stack running primarily on GPUs and propose improvements for successful KPP-2 [Poster] Open
Milestone accomplishments staged the ExaWind team for successful completion of KPP-2 challenge problem in FY23, which requires the simulation on Frontier of at least four MW-scale turbines in an atmospheric boundary layer with at least 20B…
View article: CEED ECP Milestone Report: Improve performance and capabilities of CEED-enabled ECP applications on Frontier/Aurora EA
CEED ECP Milestone Report: Improve performance and capabilities of CEED-enabled ECP applications on Frontier/Aurora EA Open
ECP Milestone Report Improve performance and capabilities of CEED-enabled ECP applications on Frontier/Aurora EA WBS 2.2.6.06, Milestone CEED-MS39
View article: CEED ECP Milestone Report: Improve performance and capabilities of CEED-enabled ECP applications on Frontier/Aurora EA
CEED ECP Milestone Report: Improve performance and capabilities of CEED-enabled ECP applications on Frontier/Aurora EA Open
ECP Milestone Report Improve performance and capabilities of CEED-enabled ECP applications on Frontier/Aurora EA WBS 2.2.6.06, Milestone CEED-MS39
View article: Demonstrate multi-turbine simulation with hybrid-structured / unstructured-moving-grid software stack running primarily on GPUs and propose improvements for successful KPP-2
Demonstrate multi-turbine simulation with hybrid-structured / unstructured-moving-grid software stack running primarily on GPUs and propose improvements for successful KPP-2 Open
The goal of the ExaWind project is to enable predictive simulations of wind farms comprised of many megawatt-scale turbines situated in complex terrain. Predictive simulations will require computational fluid dynamics (CFD) simulations for…
View article: Towards Exascale for Wind Energy Simulations
Towards Exascale for Wind Energy Simulations Open
We examine large-eddy-simulation modeling approaches and computational performance of two open-source computational fluid dynamics codes for the simulation of atmospheric boundary layer (ABL) flows that are of direct relevance to wind ener…
View article: SST ..kappa..-..omega.. Simulations of the Atmospheric Boundary Layer Including the Coriolis Effect
SST ..kappa..-..omega.. Simulations of the Atmospheric Boundary Layer Including the Coriolis Effect Open
For large-scale structures in the atmospheric boundary layer (ABL), the Coriolis effect and near-wall behavior can have a meaningful impact. For example, both the Coriolis effect and blade boundary layer impact how muchpower wind farms pro…
View article: ExaWind: Opportunity for Discovery
ExaWind: Opportunity for Discovery Open
The predictive simulation of the dynamics of modern wind turbines and wind farms is a high-performance-computing (HPC) grand challenge. Modern wind turbines are the largest rotating machines in the world, with rotor diameters exceeding 200…