A numerical study of the side-wall effects on turbulent bands in channel flow at transitional Reynolds numbers

• Published in: Computers & fluids 2022-05, Vol.240, p.105420, Article 105420
• Main Authors: Wu, Haoyang, Song, Baofang
• Format: Article
• Language: English
• Subjects: Aspect ratio; Channel flow; Collision; Decay; Direct numerical simulation; Fluid dynamics; Fluid flow; Side wall; Source code; Transitional Reynolds number; Turbulence; Turbulent band; Turbulent flow; Wall effects
• ISSN: 0045-7930; 1879-0747
• DOI: 10.1016/j.compfluid.2022.105420

We investigated the side-wall effects on turbulent bands in channel flow at transitional Reynolds numbers by direct numerical simulations using the open source spectral-element code Nektar++. The width-to-height aspect ratio of 50:1 is considered for this study. Our study shows that turbulent bands can survive the collision with the side wall above bulk Reynolds number of Re≃1000 but decay below Re≃975, i.e. the critical Reynolds number should be approximately between the two Reynolds numbers. We also discussed about the underlying mechanism for the decay of the band at low Reynolds numbers and potential effects of larger spanwise channel widths than that considered in our study. The results are informative for experimental studies of channel flow turbulence at transitional Reynolds numbers. •The collision between turbulent bands and channel side wall was studied.•A forcing technique for generating turbulent bands was implemented in Nektar++.•Results show that turbulent bands cannot survive the collision at Re≲975.•Turbulence can survive the collision above Re≃1000.•We proposed a mechanism for the decay of turbulent bands at low Reynolds numbers.•The side-wall effects should be taken care of at low Reynolds numbers in experiments.