The influence of sharp meanders on thermally stratified open channel flow

Abstract

In this study, direct numerical simulation (DNS) results for turbulent stratified open channel flow through an idealized meander with an internal heat source that models radiative heating from above are used to investigate the effect of bends on the degree of stratification and the mechanism by which the turbulence kinetic energy is produced and redistributed along the channel centreline. The pronounced local increase of TKE gains strength in the area entering halfway in the bend where a local extremum of TKE is found near the outer bank. The curve is sharp with the ratio of minimum radius of curvature to depth Rmin=B=1:67, the maximum deviation angle of q0 =110 degrees with the ratio of width over depth B/H = 10, the meander wavelength to depth l/H = 11, and the friction Reynolds number Ret = 180. We find that there is an explosion of turbulence at the location of 35% of the distance along the channel centreline which gradually weakens in the downstream part of the bend. Possible causes of this feature are discussed.