Turbulent kinetic energy budgets in wall bounded flows with pressure gradients and separation

Author(s)

Schiavo, Luiz A. C. A. ^[1] ; Wolf, William Roberto ^[1] ; Azevedo, Joao Luiz F. ^[2]

Affiliation

^[1] Univ Estadual Campinas, Sch Mech Engn, Dept Energy, BR-13083860 Campinas, SP - Brazil

^[2] Inst Aeronaut Espaco, Aerodynam Div, BR-12228904 Sao Jose Dos Campos, SP - Brazil

• Document type: Journal article
• Source: Physics of Fluids; v. 29, n. 11 NOV 2017.
• Web of Science Citations: 7

Abstract

Numerical simulations are employed to investigate the turbulent kinetic energy (TKE) budgets in turbulent channel flows with pressure gradients and separation. Incompressible, highly resolved large eddy simulations are performed for Re-tau = 170 and 615 to investigate the flow developing along a convergent-divergent channel. The aim of this work is to analyze the TKE budgets both in physical and Fourier spaces to characterize the important scales in the individual processes in such turbulent flows. The study is performed for different positions along the channel where favorable and adverse pressure gradients are present. Proper orthogonal decomposition is employed to understand the role of the most energetic structures in the TKE budgets. Results indicate that such structures account for most of the turbulent effects present in the flow, except for the transport term. A spectral TKE equation in Fourier space is developed for flows with one homogeneous direction to characterize the turbulent processes as a function of the wavelength in the channel spanwise direction. The results show that viscous effects occur at the same range of wavelengths for which production is found and that TKE is transported to the near-wall region, being dissipated by large spanwise scale motion. They also show that favorable pressure gradients change the distribution of processes along the spanwise wavelengths. In the adverse pressure gradient region, TKE is transported both toward the wall and toward the center of the channel, where it is balanced by the advection term. Published by AIP Publishing. (AU)

• FAPESP's process: 13/07375-0 - CeMEAI - Center for Mathematical Sciences Applied to Industry
• Grantee: Francisco Louzada Neto
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC
• FAPESP's process: 13/03413-4 - Investigation of noise generation and propagation by aerodynamic configurations using computational aeroacoustics
• Grantee: William Roberto Wolf
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 16/03985-6 - Numerical Investigation of Compressibility Effects in Turbulent Boundary Layers
• Grantee: Luiz Augusto Camargo Aranha Schiavo
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 14/07623-6 - Numerical study of the effect of a geometric disturbance in turbulent flows
• Grantee: Luiz Augusto Camargo Aranha Schiavo
• Support Opportunities: Scholarships in Brazil - Doctorate