Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
A PURELY LAGRANGIAN METHOD FOR SIMULATING SURFACE ROUGHNESS EFFECTS ON FLOW PAST A SOLID BODY
Submission Author:
Fabio Carvalho , SP
Co-Authors:
Fabio Carvalho, Marcos André de Oliveira, Luiz Antonio Alcântara Pereira, Alex Bimbato
Presenter: Fabio Carvalho
doi://10.26678/ABCM.ENCIT2022.CIT22-0094
Abstract
Roughness is a key parameter in fluid-structure interaction problems. Several studies link roughness with variations in aerodynamic loads, turbulence transition, and in heat transfer. Despite the importance of roughness in fluid-structure interaction analysis and the presence of well-documented experimental works, investigating roughness effects on flow hydrodynamics is still a challenging task. The roughness’s small dimensions imply discretization constraints for computational simulations and the large number of roughness topographies demand a high cost for experimental analysis. Recent studies have applied a Lagrangian vortex method associated with Large Eddy Simulation (LES) to examine the roughness influence on bluff body aerodynamics. In these works, the body surface is discretized through the panel method, in which the solid boundary is approximated to panels, over which singularities are distributed. The common type of singularity applied in these studies is the source distribution of constant density. The present paper examines the possibility of using vortex distributions of linear density as the singularity of the panel method. The discretization through flat panels with vortex distribution differs from source distribution making it possible to simulate slender bodies in addition to bluff bodies. Furthermore, the vortex distribution of linear density is of a higher order than the constant-density source distributions. In the present work, turbulence is modeled by a LES simulation adapted to Lagrangian vortex method to simulate the two-dimensional turbulent flow past a circular cylinder that is disturbed by surface roughness effects. The roughness effects are considered by injecting momentum into the body boundary layer. Three different simulations are conducted at upper-subcritical Reynolds number flows of Re = 1.0 × 10^5: first, laminar flow past a smooth circular cylinder is analyzed; after, turbulent flow is simulated past a smooth circular cylinder; and lastly, the turbulent flow around a rough circular cylinder is simulated. The rough cylinder has a relative roughness size of ε*/d* = 0.007 (ε* is the average roughness and d* is the outer cylinder diameter). The results between the laminar simulation and the turbulent, measured by the aerodynamics loads, are very similar. When the roughness is considered, the simulations were able to correctly represent the delay in the boundary layer separation and the non-zero lift force due to the roughness effect. The results indicate that the use of vortex distribution of linear density in the panel method can capture important turbulent flow characteristics and, as consequence, it can be used to simulate airfoils with roughness surfaces.
Keywords
Lagrangian Vortex method, Roughness model, aerodynamic, panel method
