Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
Study of Compressible Direct Numerical Simulations of Wave Packets Interacting with Bumps
Submission Author:
Ana Elisa Basilio , DF
Co-Authors:
Ana Elisa Basilio, Fernando H T Himeno, Marlon Sproesser Mathias, Marcello Augusto Faraco de Medeiros
Presenter: Marcello Augusto Faraco de Medeiros
doi://10.26678/ABCM.ENCIT2022.CIT22-0594
Abstract
Through Direct Numerical Simulations (DNS), this work investigates the boundary layer stability of two-dimensional wave packets over a smooth plate with a two-dimensional isolated bump immersed in a compressible laminar boundary layer flow. In the aeronautical industry, structures similar to bumps or an isolated roughness are commonly present on aircraft surfaces, and can influence the drag coefficient if there is transition to the turbulent regime in the boundary layer. Even with a relatively small influence, preventing multiple sources like these is an interesting study that can be beneficial in saving fuel costs. Thus, the objective of the current work is to develop a suitable two-dimensional mesh with the DNS code for hydrodynamic instability analysis on different Mach numbers. The numerical simulations were performed by a high order DNS for the compressible Navier-Stokes equations, developed by the Group of Aeroacoustics, Transition and Turbulence (GATT) of the Department of Aeronautical Engineering of the São Carlos School of Engineering, University of São Paulo (EESC-USP). The equations were defined in the two-dimensional domain, time, density, the velocity components, and internal energy. Their values are non-dimensional, by the characteristic velocity at the outer edge of the boundary layer, the boundary layer displacement thickness at the roughness position and initial density. A rectangular roughness is positioned on a smooth plate. Five different bumps were defined by their height, proportional to the boundary layer displacement thickness at the position of the center of the roughness on the smooth plate, that is, 0.05, 0.1, 0.2, 0.3 and 0.4. Upstream from the roughness, there is a region capable of generating disturbances that travel downstream, interacting with the roughness. The mesh used is Cartesian and initially uniform, which can be stretched in certain regions, increasing the density of nodes as needed. For each height, a different base flow was generated, as well as for each Mach number on the subsonic and transonic regimes, 0.1, 0.3, 0.6 and 0.9. For each base flow, a wave packet type of disturbance was introduced into the boundary layer through an acoustic source, which is composed by a band of Fourier modes, presenting a narrow range of frequencies exited at different amplification rates.
Keywords
direct numerical simulation, boundary layer stability, Wave packets, bumps
