The flow and heat transfer characteristics over solid wavy surface and flexible wavy surface are investigated with large eddy simulation.For the solid wavy surface

it is found that smaller wave amplitude of wavy surface does not form the recirculation in the valley.When a/λ is increased to 0.03

the flow separation appears in the valley

and the range of recirculation area becomes broader as the amplitude increases.The spindle-shaped spots with higher Nusselt number value are observed in the up-slope of the wavy surface.As the value of a/λ varies from 0.01 to 0.04

the local time-averaged Nusselt number is enhanced about 63.5% and comprehensive coefficient is increased by 0.5112.For the flexible wavy surface

the results indicate that periodic fluctuation of the wavy surface induces a periodic variation of pressure.It is also found that the spindle-shaped spots with higher Nusselt number value appear in the up-slope part of the wavy surface.When the value of a/λ varies from 0.01 to 0.04

the time-averaged local Nusselt number and comprehensive coefficient are increased by 173.1% and 1.1232

respectively. Compared with the solid wavy surface

the flexible wavy wall will remarkably enhance the heat transfer in the same amplitude and consumption of fluid pumping power.