Turbulent channel flow perturbed by triangular ripples

Autor(es)

Cunez, Fernando David ^[1] ; Gomes de Oliveira, Gabriel Victor ^[1] ; Franklin, Erick de Moraes ^[1]

Afiliação do(s) autor(es)

^[1] Univ Campinas UNICAMP, Sch Mech Engn, Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of the Brazilian Society of Mechanical Sciences and Engineering; v. 40, n. 3 MAR 2018.
• Citações Web of Science: 2

Resumo

This paper presents an experimental investigation of the perturbation of a turbulent closed-conduit flow by two-dimensional triangular ripples. Two ripple configurations were employed: one single asymmetric triangular ripple, and two consecutive asymmetric triangular ripples, all of them with the same geometry. Different water flows were imposed over either one or two ripples fixed to the bottom wall of a closed conduit, and the flow field was measured by particle image velocimetry (PIV). Reynolds numbers based on the channel height were moderate, varying between 27500 and 34700. The regime was hydraulically smooth, and the blockage ratio was significant. Experimental data for this specific case remain scarce, and the physics involved has yet to be fully elucidated. Using the instantaneous flow fields, the mean velocities and fluctuations were computed, and the shear stresses over the ripples were determined. The velocities and stresses obtained in this way for the single ripple and for the pair of ripples are compared, and the surface shear stress is discussed in terms of bed stability. Our results show that for the single and upstream ripples, the shear stress increases at the leading edge and decreases toward the crest, while for the downstream ripple it decreases monotonically between the reattachment point and the crest. The stress distribution over the downstream ripple, which is different from both the upstream and single ripples, is shown to sustain existing ripples over loose beds. (AU)

• Processo FAPESP: 15/15001-8 - Determinação experimental da camada limite turbulenta perturbada por uma ruga
• Beneficiário: Gabriel Victor Gomes de Oliveira
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 16/18189-0 - Leito fluidizado em meio líquido em tubos finos: dinâmica e instabilidades
• Beneficiário: Fernando David Cúñez Benalcázar
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 12/19562-6 - Transporte de grãos por leito móvel e instabilidades associadas
• Beneficiário: Erick de Moraes Franklin
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 16/13474-9 - Instabilidades em escoamentos granulares densos
• Beneficiário: Erick de Moraes Franklin
• Modalidade de apoio: Auxílio à Pesquisa - Regular