# Testing of subgrid scale (SGS) models for large-eddy simulation (LES) of turbulent channel flow

Montecchia, Matteo (2015) Testing of subgrid scale (SGS) models for large-eddy simulation (LES) of turbulent channel flow. [Laurea magistrale], Università di Bologna, Corso di Studio in Ingegneria aerospaziale [LM-DM270] - Forli'
Documenti full-text disponibili:
 Anteprima
Documento PDF

## Abstract

Sub-grid scale (SGS) models are required in order to model the influence of the unresolved small scales on the resolved scales in large-eddy simulations (LES), the flow at the smallest scales of turbulence. In the following work two SGS models are presented and deeply analyzed in terms of accuracy through several LESs with different spatial resolutions, i.e. grid spacings. The first part of this thesis focuses on the basic theory of turbulence, the governing equations of fluid dynamics and their adaptation to LES. Furthermore, two important SGS models are presented: one is the Dynamic eddy-viscosity model (DEVM), developed by \cite{germano1991dynamic}, while the other is the Explicit Algebraic SGS model (EASSM), by \cite{marstorp2009explicit}. In addition, some details about the implementation of the EASSM in a Pseudo-Spectral Navier-Stokes code \cite{chevalier2007simson} are presented. The performance of the two aforementioned models will be investigated in the following chapters, by means of LES of a channel flow, with friction Reynolds numbers $Re_\tau=590$ up to $Re_\tau=5200$, with relatively coarse resolutions. Data from each simulation will be compared to baseline DNS data. Results have shown that, in contrast to the DEVM, the EASSM has promising potentials for flow predictions at high friction Reynolds numbers: the higher the friction Reynolds number is the better the EASSM will behave and the worse the performances of the DEVM will be. The better performance of the EASSM is contributed to the ability to capture flow anisotropy at the small scales through a correct formulation for the SGS stresses. Moreover, a considerable reduction in the required computational resources can be achieved using the EASSM compared to DEVM. Therefore, the EASSM combines accuracy and computational efficiency, implying that it has a clear potential for industrial CFD usage.

Abstract
Tipologia del documento
Tesi di laurea (Laurea magistrale)
Autore della tesi
Montecchia, Matteo
Relatore della tesi
Correlatore della tesi
Scuola
Corso di studio
Ordinamento Cds
DM270
Parole chiave
Computational fluid dynamics, turbulence modeling, turbolenza, aerodynamics, channel flow, large-eddy simulation, direct numerical simulation, LES, DNS, KTH
Data di discussione della Tesi
19 Marzo 2015
URI