Simulation of the askervein flow. Part 2: Large-eddy simulations

• Tipo: Artigo em Revista Científica Internacional
• Data: 2007

Autores

A. Silva Lopes (Autor) Outra; José Laginha Palma (Autor) FEUP; Castro, FA (Autor) Outra

Revista

Título: Boundary-Layer Meteorology

Vol. 125 Nº 1

Páginas: 85-108

ISSN: 0006-8314

Editora: Springer Nature

Indexação

ISI Web of Knowledge - 51 Citações

Scopus - 74 Citações

Outras Informações

ID Authenticus: P-004-6XN

DOI: 10.1007/s10546-007-9195-4

Abstract (EN): Large- eddy simulations of the neutrally stratified flow over the Askervein Hill were performed, to improve the knowledge of the flow obtained from fieldmeasurements and numerical simulations with Reynolds averaged Navier- Stokes ( RANS) methods. A Lagrangian dynamic subgrid model was used but, to avoid the underdissipative character near the ground, it was merged with a damped Smagorinsky model. Simulations of a flat boundarylayer flow with this subgrid model showed that the turbulent vertical motions and shear stress were better resolved using grids with a stream to spanwise aspect ratio Delta x/ Delta y = 2 than with an aspect ratio Delta x/ Delta y = 1. Regarding the flow over the Askervein Hill, it was found that large- eddy simulations provide an acceptable solution for the mean- velocity field and better predictions of the turbulent kinetic energy in the upstream side of the hill than the k - epsilon model. However, as with the k - e model, grid convergence was not achieved in the lee side and the size of the zone with reversed flow increased with the grid refinement. Nevertheless, the existence of the intermittent separation predicted with unsteady RANS in part one of this work seems unquestionable, due to the deceleration of the flow. In our opinion, a better modelling of the decelerating boundary layer in the lee side is required to improve the results obtained using equilibrium assumptions and achieve grid convergence.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 24