A high-order LES code for spatially developing turbulent flow simulations

Author(s)

Patrícia Sartori

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Matemáticas e de Computação (ICMC/SB)
• Defense date: 2016-08-05

Examining board members

Leandro Franco de Souza; José Alberto Cuminato; Luben Cabezas Gómez; Fernando Akira Kurokawa; Oscar Mauricio Hernandez Rodriguez

• Advisor: Leandro Franco de Souza

Abstract

LES methodology is a viable alternative for the numerical solution of practical interest flows due to the computational limitations imposed by the direct resolution of all scales presented in turbulent flow. However, the detailed understanding of the turbulence phenomenon is still a challenging task as a result of its non-linear behavior and high sensitivity to initial and boundary conditions. Thus, the success of LES simulations is associated with the use of an efficient computational code, wherein the subgrid scale modeling accurately represents the flow dynamics, together with the specification of realistic inicial boundary conditions. In this context, this study aims to develop a high-order LES code combined with a method for generating velocity fluctuations to compute turbulent boundary layer flows over a flat plate. The vorticity-velocity formulation was adopted. The numerical scheme is based on the finite difference method in collocated grid, where the derivatives in the streamwise and wall-normal are approximated using high order compact finite difference schemes. We also assume periodicity in spanwise direction therefore it is adopted a spectral method in this direction. The method chosen for the temporal evolution is the 4th order Runge-Kutta method and the solution of Poisson equation solution is accessed via a multigrid algorithm. For subgrid modelling it is adopted the Wall-Adapting Local Eddy-viscosity (WALE) model. The RFG (Random Flow Generation) method was responsible for the generation of unsteady turbulent velocity signal. The results obtained were in good agreement with DNS (Direct Numerical Simulation) and LES from the literature. (AU)

• FAPESP's process: 11/00647-9 - Numerical Study of coastal cilff influence in the wind energy generation
• Grantee: Patrícia Sartori
• Support Opportunities: Scholarships in Brazil - Doctorate