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ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
COMPARATIVE ANALYSIS OF STEADY-STATE GENERATION METHODS APPLIED TO THE FLOW OVER A BACKWARDS-FACING STEP
Submission Author:
Juan Carlos Assis da Silva , RJ
Co-Authors:
Juan Carlos Assis da Silva, Leonardo Santos de Brito Alves, Rômulo Bessi Freitas, Farney Moreira
Presenter: Juan Carlos Assis da Silva
doi://10.26678/ABCM.ENCIT2022.CIT22-0065
Abstract
The laminar-turbulent transition over a flat plate is an important aerodynamics engineering problem. Transition delay can significantly reduce the viscous drag, since the laminar boundary layer has a lower skin friction than both transitional and turbulent ones. This is relevant as it leads to fuel use reduction. However, aerodynamic surfaces are usually not perfectly flat, due to the presence of things such as steps, junction gaps, contamination from dirt particles, and so on. Hence, it is often important to know how these roughness elements affect boundary layer transition. In order to do so, linear stability analysis is often used. One must first, however, obtain an accurate steady-state, so the governing equations of motion can be linearized around it to provide the linear disturbance equations. This can be a quite complicated task when the spatial discretization of the non-linear advection term requires specific techniques to reduce numerical oscillations due to strong gradients or discontinuities. The same is true when the flow is physically unstable, since the time integration also requires special techniques to numerically stabilize the physically unstable modes. The present work compares implicit multi-step schemes to obtain steady-states for the flow over a backward-facing step (BFS), namely the implicit Euler scheme and multi-step MGM schemes. Spatial discretization is done using a fifth-order weighted essentially non-oscillatory scheme for the inviscid fluxes and a fourth-order central-difference scheme for the viscous fluxes. This comparative analysis is performed using the number of interactions required to reach the imposed residue tolerances for each scheme.
Keywords
Backward Facing Step, steady state, direct numerical simulation
