Multi-Block Hierarchical Unstructured Grid Generation With Adaptation

Karman, Steve L.

doi:10.2514/6.2014-0116

Cited by 3 publications

(3 citation statements)

References 12 publications

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“…Computational grids were constructed using the commercial software Pointwise® as well as the in‐house codes Viscous Layer Extrusion (VLE) and Voxelmesh . Appropriate surface meshes were generated in Pointwise on all the viscous surfaces (blades, hub, tower and tunnel walls).…”

Section: Methodsmentioning

confidence: 99%

Blade‐resolved simulations of a model wind turbine: effect of temporal convergence

et al. 2015

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Simulations of a model wind turbine at various tip-speed-ratios were carried out using Tenasi, a node-centered, finite volume unstructured flow solver. The simulations included the tunnel walls, tower, nacelle, hub and the blades. The effect of temporal convergence on the predicted thrust and power coefficients is evaluated and guidelines for best practices are established. The results presented here are for tip-speed-ratios of 3, 6 and 10, with 6 being the design point. All simulations were carried out at a freestream velocity of 10 m s À1 with an incoming boundary layer present and the wind turbine RPM was varied to achieve the desired tip-speed-ratio. The performance of three turbulence models is evaluated. The models include a one-equation model (Spalart-Allmaras), a two-equation model (Menter SST) and the DES version of the Menter SST. Turbine performance as well as wake data at various locations is compared to experiment. All the turbulence models performed well in terms of predicting power and thrust coefficients. The DES model was significantly better than the other two turbulence models for predicting the mean and fluctuating components of the velocity in the wake.

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Section: Methodsmentioning

confidence: 99%

Blade‐resolved simulations of a model wind turbine: effect of temporal convergence

et al. 2015

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“…Young et al [56] and Powell [57] were early contributors to tree style meshing. Karman implemented SPLITFLOW [58,59], HUGG [60], PHUGG [61], and VoxelMesh [62]. Burstedde et al created p4est [63], and Tu et al at Carnegie Mellon developed Octor [64].…”

Section: Motivationmentioning

confidence: 99%

An Automatic Parallel Octree Grid Generation Software with an Extensible Solver Framework and a Focus on Urban Simulation

Hereth

2017

55th AIAA Aerospace Sciences Meeting

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The development of an automatic, dynamic, parallel, Cartesian, linear forest-of-octree grid generator and partial differential equation (PDE) solver framework is presented. This research is bundled into an application programmed with C++ which uses MPI for distributed parallelism. The application is named paros which stands for PARallel Octree Solver. In its current implementation, the application provides a 'zeroth' order representation of the target geometry, and as such, no cutcell algorithm, projection method, or immersed boundary condition are implemented. In this case, 'zeroth' order means that no geometry is ever exactly represented in the final computational mesh: an octree element is either completely in the domain or entirely outside of it. Any element that contains or is intersected by a geometry facet is removed from the final mesh which results in a 'blocky' or 'stepped' geometry representation and simplifies boundary computations. The computational octree mesh creation is completely parallel and automated. The algorithm is dynamic in the sense that it is repartitioned dynamically throughout the grid generation process to maintain optimal load balancing during all phases of the mesh genesis. A linear octree data structure is used to store the octree mesh elements and is leveraged for optimal load balancing. An additional hierarchical octree is used to significantly improve algorithms that suffer from this linear storage paradigm. This work focuses on, but is not limited to, applications related to urban simulations and may be applied to plume/contaminant propagation. Within the PDE solution framework a cell-centered, incompressible, unsteady, Navier-Stokes solver with an energy term to account for thermal buoyancy iv is implemented and validated using canonical test cases. Turbulence closure is implemented in the form of the Smagorinski large eddy simulation (LES) model. The parallel grid generation and solution process is tested on a large scale cityscape geometry and shown to be robust and efficient.Additionally, an implementation of the compressible Navier-Stokes equations is coded within the framework. The framework is extensible such that adding other types of numerical PDE solvers should not be difficult. Other features including adaptive mesh refinement (AMR) and contaminant transport functionality are included. v DEDICATION This research and dissertation is dedicated to my amazing wife: Sarah Dawn Hereth, my two handsome sons: Gabriel Alan and Jude Isaiah, and my two beautiful daughters: Lael Sophia and Emery Dawn. Without their love and patience, I could never have completed this endeavor.I also wish to dedicate this work to my mother, Brenda Louise Hereth, who left us too early; she never doubted my ability and intelligence, and continually encouraged and pushed me to better myself and pursue knowledge. She would be beyond proud if she were with us today. I miss you Mom. vi ACKNOWLEDGEMENTSThis dissertation brings to fruition a long journey that began over nine years ago. Over these years I...

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“…The off-body region of the hybrid mesh was removed and replaced by an automated hierarchical unstructured meshing process termed voxel meshing. The hierarchical meshing process, described in work by Karman, runs in a transformed Cartesian space 8 . Voxel meshing requires minimal user input consisting of a Cartesian bounding box and the maximum voxel size.…”

Section: Hybrid Overset Generationmentioning

confidence: 99%

Mesh Generation for the NASA High Lift Common Research Model (HL-CRM)

Woeber

Gantt

Wyman

2017

55th AIAA Aerospace Sciences Meeting

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Four types of CFD meshes (multi-block structured, unstructured tetrahedral, unstructured hybrid, and hybrid overset) were generated for the NASA High Lift Common Research Model (HL-CRM). Lessons learned during this experience are documented herein, from geometry processing through generation of the final volume meshes. All meshes are provided as a baseline to build a mesh family for a mesh sensitivity study for the 3 rd AIAA High Lift Prediction Workshop and in the 1 st AIAA Geometry and Mesh Generation Workshop.

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Multi-Block Hierarchical Unstructured Grid Generation With Adaptation

Cited by 3 publications

References 12 publications

Blade‐resolved simulations of a model wind turbine: effect of temporal convergence

Blade‐resolved simulations of a model wind turbine: effect of temporal convergence

An Automatic Parallel Octree Grid Generation Software with an Extensible Solver Framework and a Focus on Urban Simulation

Mesh Generation for the NASA High Lift Common Research Model (HL-CRM)

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