Unconditionally Stable Calculation of Transonic Potential Flow Through Cascades Using an Adaptive Mesh for Shock Capture

1983 ◽  
Vol 105 (3) ◽  
pp. 504-513 ◽  
Author(s):  
J. R. Caspar
Keyword(s):  
Physical Space ◽  
Adaptive Mesh ◽  
Control Area ◽  
Problem Analysis ◽  
Full Potential ◽  
Unconditionally Stable ◽  
Potential Flows ◽  
Flow Through ◽  
Iterative Procedures ◽  
Coarse Meshes

This paper describes an unconditionally stable procedure for calculating practical transonic potential flows through two-dimensional cascades. The full potential equation is cast in conservation form and approximated in physical space with centered control area techniques. Discrete analogs of nonphysical weak solutions are eliminated by the introduction of artificial viscosity in supersonic regions using artificial compressibility in which the density is evaluated a certain distance upstream from where it is to be applied. An explicit treatment of the density causes standard iterative procedures to diverge, except on relatively coarse meshes on which shocks are poorly captured. Instead, the insight of a model problem analysis is used to treat the density partially and implicitly.

Unconditionally Stable Calculation of Transonic Potential Flow Through Cascades Using an Adaptive Mesh for Shock Capture

1982 ◽  
Author(s):  
J. R. Caspar
Keyword(s):  
Physical Space ◽  
Adaptive Mesh ◽  
Control Area ◽  
Problem Analysis ◽  
Full Potential ◽  
Unconditionally Stable ◽  
Potential Flows ◽  
Flow Through ◽  
Iterative Procedures ◽  
Coarse Meshes

This paper describes an unconditionally stable procedure for calculating practical transonic potential flows through two-dimensional cascades. The full potential equation is cast in conservation form and approximated in physical space with centered control area techniques. Discrete analogs of nonphysical weak solutions are eliminated by the introduction of artificial viscosity in supersonic regions using artificial compressibility in which the density is evaluated a certain distance upstream from where it is to be applied. An explicit treatment of the density causes standard iterative procedures to diverge except on relatively coarse meshes on which shocks are poorly captured. Instead, the insight of a model problem analysis is used to treat the density partially and implicitly.

Mach Number Influence on Reduced-Order Models of Inviscid Potential Flows in Turbomachinery

2002 ◽  
Vol 124 (4) ◽  
pp. 977-987 ◽  
Author(s):  
Bogdan I. Epureanu ◽  
Earl H. Dowell ◽  
Kenneth C. Hall
Keyword(s):  
Mach Number ◽  
Steady Flow ◽  
Inviscid Flow ◽  
Reduced Order Models ◽  
Reduced Order ◽  
Spatial Gradients ◽  
Potential Flows ◽  
Proper Orthogonal Decomposition Technique ◽  
Flow Through ◽  
Phase Angles

An unsteady inviscid flow through a cascade of oscillating airfoils is investigated. An inviscid nonlinear subsonic and transonic model is used to compute the steady flow solution. Then a small amplitude motion of the airfoils about their steady flow configuration is considered. The unsteady flow is linearized about the nonlinear steady response based on the observation that in many practical cases the unsteadiness in the flow has a substantially smaller magnitude than the steady component. Several reduced-order modal models are constructed in the frequency domain using the proper orthogonal decomposition technique. The dependency of the required number of aerodynamic modes in a reduced-order model on the far-field upstream Mach number is investigated. It is shown that the transonic reduced-order models require a larger number of modes than the subsonic models for a similar geometry, range of reduced frequencies and interblade phase angles. The increased number of modes may be due to the increased Mach number per se, or the presence of the strong spatial gradients in the region of the shock. These two possible causes are investigated. Also, the geometry of the cascade is shown to influence strongly the shape of the aerodynamic modes, but only weakly the required dimension of the reduced-order models.

Meshless numerical simulation of (full) potential flows in a nozzle by genetic algorithms

2003 ◽  
Vol 43 (10-11) ◽  
pp. 1167-1176 ◽  
Author(s):  
G. Winter ◽  
J. C. Abderramán ◽  
J. A. Jiménez ◽  
B. González ◽  
E. Benitez ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Genetic Algorithms ◽  
Full Potential ◽  
Potential Flows

Hacking Together Globally

2017 ◽  
Vol 3 (1) ◽  
pp. 95-108 ◽  
Author(s):  
Jeremy Hunsinger
Keyword(s):  
Real Time ◽  
Video Analysis ◽  
Physical Space ◽  
Creative Activity ◽  
Video Streams ◽  
The People ◽  
Flow Through ◽  
Global Movements ◽  
Digital Spaces

Abstract This paper examines events that occur synchronously around the globe at hackerspaces: during Global Synchronous Hackathons, participants use video streams to share experiences, work and interact in real time. This paper analyses synchronous hackathons through video repositories of these events. It aims at discerning what norms are enacted in presented hacking experiences and how those norms are communicated across the video streams. Hacking in these cases should be thought of as the creative activity of using technology to build something that solves a problem or challenge. Hackerspaces are social workshops and communities renting a physical space and usually interacting in digital spaces. In these environments, individuals are involved in hacking as combined social as well as solitary activities which, to some extent, embody certain norms. Individuals also create the “technological drama”; that is they create the discourse around the objects that inform their use and embed them in cultures. These cultures and their discourses possess norms which flow through them and exist around the objects. Members of hackerspaces commonly participate in the aforementioned “Synchronous Hackathons.” By comparing videos of these hackathons, I stress the relevance of norms which are not usually listed in reflections on hacker ethics such as those of Steven Levy or Pekka Himmanen: the awareness of the global other or the awareness of what might be termed “the cosmopolitical.” These norms seek to care for and attend to the people who exist at a distance. This transformation of local to global “hacker ethics” demonstrates the growth of the recognition, at least internally, that hackerspaces embody more than their local concerns: they are part of global movements with global interests and globalising norms. The video analysis is used to demonstrate the globalising norms of these communities as the norms surrounding cosmopolitics become more prevalent in their discourses.

scholarly journals Adaptive Mesh Refinement Strategies for a Novel Modelof Immiscible Fluid Flow in Fractures

2021 ◽  
Author(s):  
Sobhan Hatami ◽  
Stuart Walsh
Keyword(s):  
Adaptive Mesh Refinement ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Uniform Grid ◽  
Immiscible Fluid ◽  
Multiphase Model ◽  
Front Tracking Method ◽  
Lattice Boltzmann Simulations ◽  
Refined Meshes ◽  
Flow Through

In this paper, we consider two Adaptive Mesh Refinement (AMR) methods to simulate flow through fractures using a novel multiphase model. The approach represents the fluid using a two-dimensional parallel-plate model that employs techniques adapted from lattice-Boltzmann simulations to track the fluid interface. Here, we discuss different mesh refinement strategies for the model and compare their performance to that of a uniform grid. Results from the simulations are demonstrated showing excellent agreement between the model and analytical solutions for both unrefined and refined meshes. We also present results from the study that illustrate the behavior of the AMR front-tracking method. The AMR model is able to accurately track the interfacial properties in cases where uniform fine meshes would significantly increase the simulation cost.The ability of the model to dynamically refine the domain is demonstrated by presenting the results from an example with evolving interfaces.

Shock fitting in conical supersonic full potential flows

1985 ◽  
Vol 13 (3) ◽  
pp. 319-335 ◽  
Author(s):  
M.J. Siclari ◽  
M. Visich
Keyword(s):  
Full Potential ◽  
Potential Flows ◽  
Fitting In ◽  
Shock Fitting

scholarly journals Fragmented Narratives: Exploring Storytelling approaches for Animation in Spatial Context

2021 ◽  
Vol 6 (2) ◽  
pp. 7-27
Author(s):  
Lea Vidakovic ◽  
Keyword(s):  
Flat Surface ◽  
State Of The Art ◽  
Physical Space ◽  
Full Potential ◽  
Moving Image ◽  
Narrative Structures ◽  
Narrative Device ◽  
Narrative Forms ◽  
The Relationship ◽  
New Strategies

Animation is considered a prevalent medium in contemporary moving image culture, which increasingly appears across non-conventional surfaces and spaces. And while storytelling in animation films has been extensively theorized, narrative forms that employ physical space as part of storytelling have been less explored. This paper will examine the narrative aspect of animation works which are screened outside the traditional cinematic venues. It will look at how these animation works tell stories differently - using the full potential of the space, as a narrative device, a tool, and a stage where the narratives unfold. This paper will look at the historical perspective and the state of the art in animation installation today, exploring the relationship between the space and narrative in pre-cinematic, cinematic and post-cinematic conditions. It will examine how narrative structures in animation have changed over time, on their way from the black box of the cinema to the white cube of the gallery and even further, where they became part of any space or architecture. Through case studies of works by Tabaimo, Rose Bond, William Kentridge and other relevant artists, the interdependency of the narrative and the space where it appears will be explored, in order to identify new strategies for storytelling in animation. The aim of this paper is to emphasize the storytelling novelty that animation installations offer, which goes beyond the narrative structures that we are used to see on a single flat surface.

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