Numerical simulation of the receptivity of Tollmien-Schlichting waves due to acoustic waves inciding on rectangular hump and gap in compressible flow

• Ano de defesa: 2022
• Autor(a) principal: Santos, Pedro Henrique Rosa dos
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: acoustic; acústica; bump; cavidade; cavity; DNS; receptividade; receptivity; ressalto; roughness; rugosidade
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/18/18161/tde-03052023-171934/

The acoustic receptivity of TS waves due to localized roughness (gaps and bumps) inside a compressible laminar boundary layer has been studied. The method utilized was Direct Numerical Simulation with high-order compact finite differences and body fitting mesh. The parameter space covered small rectangular positive or negative non uniformities, and an initial non-linear bump height, as well as different Mach numbers. A novel way to measure the receptivity was suggested. The comparison with the simulation data from the literature provided a validation and indicated that this procedure leads to more reliable values of receptivity. Experimental data from literature was taken for comparison, and the possible implications of the pressure gradient in the evolution of the TS wave in a wind tunnel were evaluated as a possible explanation for the differences encountered. The results showed in this paper also suggest that the non linearity of the receptivity of bumps starts to be significant at height greater about 12.6% of δ*b (undisturbed Blasius displacement thickness). Moreover, the receptivity of gaps seemed to be smaller than the receptivity of bump, which was not predicted by the linearised theories, such as the Finite Reynolds Number Theory of Choudhari and Streett (1992). At last, the results show that the receptivity decreases with the Mach number, and this trend appears to be in agreement with Raposo, Mughal and Ashworth (2019).