  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 around 1000
but decay below Re around 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.
