Showing papers by "William J. Rider published in 2002"
TL;DR: In this paper, the authors present a rationale for the success of nonoscillatory finite volume difference schemes in modeling turbulent flows without need of subgrid scale models, and demonstrate that these truncation terms have physical justification, representing the modifications to the governing equations that arise when one considers the motion of finite volumes of fluid over finite intervals of time.
Abstract: We present a rationale for the success of nonoscillatory finite volume (NFV) difference schemes in modeling turbulent flows without need of subgrid scale models. Our exposition focuses on certain truncation terms that appear in the modified equation of one particular NFV scheme, MPDATA. We demonstrate that these truncation terms have physical justification, representing the modifications to the governing equations that arise when one considers the motion of finite volumes of fluid over finite intervals of time.
216 citations
TL;DR: A simple modification of the Riemann solver's dissipation returns the method to stability and has a smaller truncation error than the corresponding method with an upwind flux for the RK2‐DG(1) method.
Abstract: While conducting a von Neumann stability analysis of discontinuous Galerkin methods we discovered that the classic Lax-Friedrichs Riemann solver is unstable for all time-step sizes. We describe a simple modification of the Riemann solver's dissipation returns the method to stability. Furthermore, the method has a smaller truncation error than the corresponding method with an upwind flux for the RK2-DG(1) method
21 citations
18 Jun 2002
TL;DR: In this article, the authors propose a method to solve the problem of "uniformity" and "uncertainty" in the context of health care, and propose a solution.
Abstract: 1
13 citations
01 Jan 2002
TL;DR: In this paper, an extension of the MILES concept introduced by Boris, where monotone numerical algorithms are used for large eddy simulation (LES), is presented. And the authors show that the implicit modeling includes elements of nonlinear eddy viscosity, scale-similarity and an effective dynamic model.
Abstract: Over the past decade there has been an increasing amount of evidence that high resolution numerical methods for hyperbolic partial differential equations have an embedded (or “implicit”) turbulence model. The present chapter describes this general class of methods and outlines the basic structure of high resolution methods as an effective turbulence model in the context of large eddy simulation (LES). This discussion is an extension of the MILES concept introduced by Boris, where monotone numerical algorithms are used for LES (MILES is an acronym for monotone integrated LES). We show that the implicit modeling includes elements of nonlinear eddy viscosity, scale-similarity and an effective dynamic model. In addition, we give examples of both success and failures with currently available methods and examine the effects of the embedded modeling in contrast to widely used subgrid scale (SGS) models.
6 citations