Insights into the particle-free and particle-laden turbulent flow statistics in sharply bent channels

Turbulence in canonical wall-bounded and particle-laden flows shows a wide range of

regimes due to considerable interaction between scales. Reynolds number is primarily used

to characterize the fluid dynamics and particle-laden fluid corresponding to single phase

and particle-laden channel flows. Nonetheless, different flow behaviour exists in curved

channels even at a fixed Reynolds number, as delineated by Geert Brethouwer (J. Fluid

Mech., vol. 931, 2022, pp. A21). In our study, we show the behavior of wall-bounded

turbulent flows with and without particles in sharply bent channels by exploring the time

averaged velocity profiles at various channel cross-section. The well-known logarithmic

behaviour of the time averaged normalized velocity profile is found to be retained, where

the von Kármán and the additive constants assume altered values depending on the bend

angle. An enhanced near-wall fluctuations at the bend is obtained owing to the diffusion of

counter rotating vortices that led to increased turbulent activity in case of particle-free as

well as in particle-laden turbulent channel flows. Turbulent kinetic energy (TKE) budget

for particle-free and particle-laden cases are elaborated for various bend inclinations at

different sections of the channel, which establish that TKE is modulated at the bend with

an overall attenuation on loading the channel with particles.