arXiv subjects

Thor Gjesdal

Publications and source records attributed to Thor Gjesdal.

3 recordsLinked to original sources

arXiv2006

Variational multiscale turbulence modelling in a high order spectral element method

One of the more promising recent approaches to turbulence modelling is the Variational Multiscale Large Eddy Simulation (VMS LES) method proposed by Hughes et al. [Comp. Visual. Sci., vol. 3, pp. 47-59, 2000]. This method avoids several conceptual issues of traditional filter-based LES by employing a priori scale partitioning in the discretization of the Navier-Stokes equations. Most applications of VMS LES reported to date have been based on hierarchical bases, in particular global spectral methods, in which scale partitioning is straightforward. In the present work we describe the implementation of the methodology in a three-dimensional high-order spectral element method with a nodal basis. We report results from coarse grid simulations of turbulent channel flow at different Reynolds numbers to assess the performance of the model. Key words: Large eddy simulation, variational multiscale method, spectral element method, incompressible flow 1991 MSC: 76F65, 65M60, 65M70 PACS: 47.27.Eq, 02.70.Hm, 02.70.Dh

physics.comp-ph↗

arXiv2003

Spectral element simulations of buoyancy-driven flow

This paper is divided in two parts. In the first part, a brief review of a spectral element method for the numerical solution of the incompressible Navier-Stokes equations is given. The method is then extended to compute buoyant flows described by the Boussinesq approximation. Free convection in closed two-dimensional cavities are computed and the results are in very good agreement with the available reference solutions.

physics.comp-ph↗

arXiv2003

Implicit-explicit methods based on strong stability preserving multistep time discretizations

In this note we propose and analyze novel implicit-explicit methods based on second order strong stability preserving multistep time discretizations. Several schemes are developed, and a linear stability analysis is performed to study their properties with respect to the implicit and explicit eigenvalues. One of the proposed schemesis found to have very good stability properties, with implicit A-stability for the entire explicit stability domain. The properties of the other proposed schemes are comparable to those of traditional methods found in the literature.

math.NA↗