We carried out direct numerical simulations of turbulent Rayleigh-Benard convection(RBC)with accounting for both the roughness and the external vibration over the Rayleigh number range 10^(7)≤Ra≤10^(11) and the vibr...We carried out direct numerical simulations of turbulent Rayleigh-Benard convection(RBC)with accounting for both the roughness and the external vibration over the Rayleigh number range 10^(7)≤Ra≤10^(11) and the vibration frequency range 0<ω<1400.The triangular rough elements are uniformly distributed over the top and bottom surfaces,and the vibration is applied in the horizontal direction.It is shown that under the combined action of roughness and horizontal vibration,with increasing the vibration frequency ω,the heat transfer is initially decreased a little and then greatly enhanced after ω exceeds the critical value.The physical reason for massive heat-transfer-enhancement is that high frequency vibration destabilizes thermal boundary layers(BL)over rough surfaces,triggers abundant emissions of thermal plumes,and strengthens the motion of large-scale circulation(LSC),which consequently thins the thickness of thermal BL and heightens the convective transport.In addition,it is shown that vibration-induced heat-transfer-enhancement can obviously affect the scaling behavior between the heat flux and the Rayleigh number,and the scaling exponent increases with increasing ω,whereas the influence of vibration on the scaling behavior between the intensity of LSC and Ra is very weak.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11988102,92052201,91852202,H825204,and 11972220)the Program of Shanghai Academic Research Leader(Grant No.19XD1421400)+1 种基金Shanghai Science and Technology Program(Grant Nos.19JC1412802 and 20ZR14I9800)China Postdoctoral Science Foundation(Grant No.2020M681259).
文摘We carried out direct numerical simulations of turbulent Rayleigh-Benard convection(RBC)with accounting for both the roughness and the external vibration over the Rayleigh number range 10^(7)≤Ra≤10^(11) and the vibration frequency range 0<ω<1400.The triangular rough elements are uniformly distributed over the top and bottom surfaces,and the vibration is applied in the horizontal direction.It is shown that under the combined action of roughness and horizontal vibration,with increasing the vibration frequency ω,the heat transfer is initially decreased a little and then greatly enhanced after ω exceeds the critical value.The physical reason for massive heat-transfer-enhancement is that high frequency vibration destabilizes thermal boundary layers(BL)over rough surfaces,triggers abundant emissions of thermal plumes,and strengthens the motion of large-scale circulation(LSC),which consequently thins the thickness of thermal BL and heightens the convective transport.In addition,it is shown that vibration-induced heat-transfer-enhancement can obviously affect the scaling behavior between the heat flux and the Rayleigh number,and the scaling exponent increases with increasing ω,whereas the influence of vibration on the scaling behavior between the intensity of LSC and Ra is very weak.
