中文摘要：

对方腔一侧壁面温度随时间按正弦规律变化、充满CuO-水纳米流体的二维方腔内的非稳态自然对流换热进行了数值研究。在相关参数一定的条件下,研究了Ra数、纳米颗粒体积份额φ和纳米颗粒布朗运动对自然对流换热特性的影响。数值模拟结果表明：考虑布朗运动时壁面时均Nu数均大于不考虑布朗运动时的相应值;不考虑布朗运动时,时均Nu数均随φ的增大而增大;而考虑布朗运动时,当Ra数较小时,时均Nu数均随φ的增大而增大,而Ra数较大时,存在有最佳的φ值,可使时均Nu数达到最大值。

英文摘要：

Transient natural convection of CuO-water nanofluid in a square cavity submitted to a time-periodic temperature boundary is studied numerically.The effects of Rayleigh number,volume fraction of nanoparticles,and Brownian motion on the flow and temperature patterns as well as the heat transfer rate within the cavity are presented.It is found that the time-averaged heat transfer rate increases as particle volume fraction and Rayleigh number increase.It is further observed that when Brownian motion is considered,the time-averaged heat transfer rate is higher than the result of the analysis in which Brownian motion is neglected.