变温壁驱动腔内热蠕流特性的离散统一气体动理学格式模拟  

Discrete unified gas kinetic simulation of characteristics of variable temperature wall driven thermal creep flow in cavity

作　　者：刘赞奇 罗源 翁万良 何清 陶实 LIU Zanqi;LUO Yuan;WENG Wanliang;HE Qing;TAO Shi(Guangdong Provincial Key Laboratory of Distributed Energy Systems,Dongguan University of Technology,Dongguan 523808,China)

机构地区：[1]东莞理工学院,广东省分布式能源系统重点实验室,东莞523808

出　　处：《物理学报》2025年第4期200-213,共14页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:52476148,51906044)资助的课题.

摘　　要：为考察壁面温度变化对受限空间内稀薄气体流动与传热特性的影响,采用离散统一气体动理学格式(DUGKS)模拟研究了方腔内的热蠕流动.腔体四周为静止漫反射恒温壁面,上、下壁温度则随时间周期性变化.模拟的参数范围如下:变温频率0.5≤S_(t)≤5.0、变温振幅0.1≤A_(h)≤0.8和克努森数0.01≤Kn≤10.数值结果表明:方腔内气体流动与传热特性呈现周期性变化,且不会出现反傅里叶热传递.变温频率、振幅和克努森数的提高均可增强腔内热蠕流动强度,且变温壁面附近速度滑移和温度跳跃增大.St和Kn的增大导致出现传热滞后现象,壁面换热能力减弱.特别地,当St=0.5较小时腔内观察到复杂涡流结构;St=5.0时气体由变温壁面向腔体水平中心线均匀流动,涡流消失的同时左、右壁面中点附近由吸热区转变为放热区.A_(h)增大时腔内温度场和速度场结构变化不大,而壁面传热强度减小.In order to examine the influence of wall temperature change on the flow and heat transfer properties of rarefied gas in restricted space,the discrete unified gas kinetic scheme(DUGKS)is used to simulate the thermal creep flows in a square cavity.All the boundaries of the cavity are stationary diffuse reflection walls.The temperature of left wall and right wall are lower,and the temperature of the upper wall and the lower wall are both subjected to periodic variation.The simulation parameters considered in the present work are set as follows:the Knudsen number Kn is in a range 0.01–10,temperature change frequency St in a range of 0.5–5,and temperature change amplitude A_(h)in a range of 0.1–0.8.The results indicate that the velocity field and temperature field in the cavity exhibit periodic variations.No inverse Fourier heat transfer phenomenon is observed within the parameter ranges studied.The intensity of the thermal creep flow can be increased by increasing the frequency,temperature,and the Knudsen number.This can also raise the temperature jump and velocity slip close to the temperature change walls.Heat transfer lag and a reduction in the heat transfer capability of the wall are caused by increasing St and Kn.When St is small,say,St=0.5,a complex vortex structure is seen in the cavity.As the value of St rises to 5,the vortex disappears,the gas travels from the variable temperature wall to the horizontal centerline of cavity,and the region close to the middle of the left wall and right wall changes from an endothermic zone to an exothermic zone.Furthermore,the temperature field and velocity field inside the cavity hardly change,but the degree of heat transfer on the wall decreases with the increase of A_(h).The main results are shown in the figure attached below.This work provides helpful recommendations for designing the MEMS devices by using pulsed heating.

关 键 词：热蠕流 离散统一气体动理学 变温壁面 漫反射边界 

分 类 号：G63[文化科学—教育学]