Simulation of fluid dynamics around complex urban geometries

Cybyk, Bohdan; Boris, J. P.; Young, T. R.; Emery, Mark H.; Cheatham, Sally

doi:10.2514/6.2001-803

Cited by 17 publications

(3 citation statements)

References 5 publications

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“…Comparison of the horizontal velocity profile for natural convection with Re = 1000..... or biological agents into urban environments, either purposely or accidentally, there is increasing interest in the role CFD can play in optimizing responses to such events [1][2][3][4][5]. It is valuable to be able to predict where and how a potentially toxic contaminant might spread once released into a city environment in order to provide first responders the means to perform focused disaster mitigation.…”

Section: 7mentioning

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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Section: 7mentioning

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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“…In addition to uid dynamics to compute the plasma ow, the simulation of the solar eruption includes descriptions of the behavior of the electric and magnetic elds needed to compute the reconnecting magnetic eld lines. The thermonuclear supernova involves a gravitational eld that varies from zero gravity at the center (0 cm) to about 5 £ 10 6 times Earth gravity at the outer edge (10 8 cm) of the star, and a complex series of nuclear interactions that transforms 12 C and 16 O into a series of heavier elements such as neon, magnesium, silicon, and up to nickel.…”

Section: Physical Complexitymentioning

confidence: 99%

Matchsticks, Scramjets, and Black Holes: Numerical Simulation Faces Reality

Oran

2002

AIAA Journal

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The evolution of the science and art of numerical simulation of complex, complicated uid ows has made enormous strides in the past 40 years. We have progressed from relatively simpli ed one-dimensional steady-state results to fully three-dimensional, time-dependent simulations including very complex physics. These advances have been driven by new computational hardware, new algorithms for solving the equations, and the real need for this technology. The broad range of applications that are possible are emphasized and some of what we can now do, what we have learned, and where we might go with this exciting technology in the future is described.

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“…The FAST3D-CT three-dimensional flow simulation model [1,17,18] is based on the scalable, low dissipation Flux-Corrected Transport (FCT) convection algorithm [19,20]. FCT is a high-order, monotone, positivity-preserving method for solving generalized continuity equations with source terms.…”

Section: Miles For Urban Scale Simulationsmentioning

confidence: 99%

Large Scale Urban Simulations with FCT

Patnaik¹,

Boris²,

Grinstein³

et al.

Flux-Corrected Transport

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Summary. Airborne contaminant transport in cities presents challenging new requirements for CFD. The unsteady flow physics is complicated by very complex geometry, multi-phase particle and droplet effects, radiation, latent, and sensible heating effects, and buoyancy effects. Turbulence is one of the most important of these phenomena and yet the overall problem is sufficiently difficult that the turbulence must be included efficiently with an absolute minimum of extra memory and computing time. This paper describes the Monotone Integrated Large Eddy Simulation (MILES) methodology used in NRL's FAST3D-CT simulation model for urban contaminant transport (CT) (see [1] and references therein). We also describe important extensions of the underlying Flux-Corrected Transport (FCT) convection algorithms to further reduce numerical dissipation in narrow channels (streets).

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Simulation of fluid dynamics around complex urban geometries

Cited by 17 publications

References 5 publications

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

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

Matchsticks, Scramjets, and Black Holes: Numerical Simulation Faces Reality

Large Scale Urban Simulations with FCT

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