TY - JOUR

T1 - Large-eddy simulations of heat transfer in asymmetric rib-roughened ducts

T2 - Effects of rotation

AU - Salvagni, Alessandro

AU - Borello, Domenico

AU - Rispoli, Franco

AU - Hanjalić, Kemal

PY - 2017/12/1

Y1 - 2017/12/1

N2 - We report on large-eddy simulations (LES) of the effects of system rotation on heat transfer in a fully-developed flow in an asymmetrically-ribbed rectangular duct at Re=[Formula presented]=15000 where Dh is the hydraulic diameter and U0 the bulk flow velocity. The bottom duct wall, ribbed by flow-normal, equally-distanced square-sectioned ribs, was uniformly heated (except for the ribs) with an imposed constant heat flux. The duct was rotated with a spanwise angular velocity Ω corresponding to two rotation number Ro=[Formula presented]=±0.3, destabilising and stabilising respectively the ribbed-wall adjacent flow. The computational method and the treatment of heat transfer were verified and validated in prior simulations of generic well-documented reference configurations, rotating plane channel and non-ribbed duct flows. The well-resolved LES gave some new insight into the rotation effects on flow and heat transfer, providing information that are not easily accessible to experiments. An attempt is made to identify and distinguish the physical mechanisms of heat transfer enhancement and suppression by system rotation, rib-induced modifications of secondary motion, and the direct effects on the turbulence statistics, especially on the budgets of the turbulent kinetic energy, temperature variance and turbulent heat flux components.

AB - We report on large-eddy simulations (LES) of the effects of system rotation on heat transfer in a fully-developed flow in an asymmetrically-ribbed rectangular duct at Re=[Formula presented]=15000 where Dh is the hydraulic diameter and U0 the bulk flow velocity. The bottom duct wall, ribbed by flow-normal, equally-distanced square-sectioned ribs, was uniformly heated (except for the ribs) with an imposed constant heat flux. The duct was rotated with a spanwise angular velocity Ω corresponding to two rotation number Ro=[Formula presented]=±0.3, destabilising and stabilising respectively the ribbed-wall adjacent flow. The computational method and the treatment of heat transfer were verified and validated in prior simulations of generic well-documented reference configurations, rotating plane channel and non-ribbed duct flows. The well-resolved LES gave some new insight into the rotation effects on flow and heat transfer, providing information that are not easily accessible to experiments. An attempt is made to identify and distinguish the physical mechanisms of heat transfer enhancement and suppression by system rotation, rib-induced modifications of secondary motion, and the direct effects on the turbulence statistics, especially on the budgets of the turbulent kinetic energy, temperature variance and turbulent heat flux components.

KW - Channel

KW - Duct

KW - Energy equation

KW - Heat transfer

KW - LES

KW - Rib-roughened duct

KW - Rotation

KW - Turbulent heat flux

KW - CHANNEL FLOW

KW - CONVECTION

KW - TURBULENT

UR - http://www.scopus.com/inward/record.url?scp=85032748882&partnerID=8YFLogxK

U2 - 10.1016/j.ijheatfluidflow.2017.09.019

DO - 10.1016/j.ijheatfluidflow.2017.09.019

M3 - Article

AN - SCOPUS:85032748882

VL - 68

SP - 373

EP - 385

JO - International Journal of Heat and Fluid Flow

JF - International Journal of Heat and Fluid Flow

SN - 0142-727X

ER -