The turbulent flow and heat transfer characteristics of rectangular channel with groove bottom surface are investigated by use of large eddy simulation.To validate the accuracy and reliability of the simulation method

the simulation results for plate channel are compared with the direct numerical simulation results of reference. The heat transfer surface Nusselt number is compared to that calculated by Dittus-Boelter equation.The differences are less than 5%.From the simulation results for rectangular channel with groove bottom surface

it is found that the groove structure of the channel bottom surface changes the flow structure near the groove surface.Groove heights and lengths influence the flow resistance and heat transfer effect.Compared with the plate rectangular channel with specific geometric parameters

the time-averaged Nusselt number of groove surface is increased nearly by 50.5%

and the time-averaged friction drag coefficient decreases by 35.17%

and the comprehensive coefficient is increased by 73.89%.The flow structure in the channel shows that there is a region near the groove surface

in which the flow is perpendicular to the wall.The fluid flows forward and backward in the vertical flow region.Since the friction drag coefficient does not increase significantly and the Nusselt number is obviously enhanced

the comprehensive flow characteristic is the best.