特殊条件下矩形封闭空腔内自然对流数值研究

在封闭腔侧壁均匀加热且同时顶壁均匀冷却的特殊条件下 ,应用新的近壁面网格加密法 ,针对一个系列的瑞利数和纵横比 ,进行了详细的稳态自然对流换热问题的数值模拟 .通过分析诸多工况对流动形式和能量传递的影响 ,发现当纵横比较大时 (at>1) ,瑞利数对传热的影响比较明显 ;而当纵横比较小 (at<1)和瑞利数较大时 ,纵横比的影响比较明显 .对数值结果进行了回归 ,得到了Nu和Ra的关联式 ,其精度较以前的近似拟合公式要高

Natural convection in rectangular enclosures heated from one side and cooled from ceiling

The numerical simulations were undertaken for steady natural convection of air in a two dimensional enclosure isothermally heated from one side and cooled from the ceiling. The conservation equations were solved for a series of Rayleigh numbers and for severd different aspect ratios. For the variation of physical characteristics of flow near the wall was violent, a new grid compression arithmetic near the wall was used. According to the result of simulations, the effect of Rayleigh numbers and aspect ratios on flow pattern and heat transfer were investigated. The effect of Rayleigh numbers on heat transfer was found to be more significant when the enclosure was shallow( a t>1), and the influence of aspect ratio was stronger when the enclosure was tall ( a t>1) and the Rayleigh number was high. The more precise correlations between average Nu and Ra were also presented.