倾斜方腔内混合纳米流体自然对流问题

Natural Convection of Hybrid Nanofluids in an Inclined Square Cavity

【目的】研究方腔倾斜角度和Ra数对混合纳米流体流动与传热的影响机理。【方法】首先时间上采用Adams-Bashforth和向后差分结合的二阶半隐格式进行离散,其次采用改进的投影算法对速度和压力进行耦合处理,最后采用配置点谱方法求解所有的无量纲控制方程。【结果】经数值验证之后,通过改变方腔倾斜角度(0≤θ≤π/4)和Ra数(104≤Ra≤106),来分析对流场、温度场和Nu数的影响。发现随着方腔倾斜角度的增大,Nu数先增大后变小;随着Ra数的增大,流动与传热都增大。【结论】方腔倾斜角度为π/6和Ra数为10^(6)时,传热效果最佳。

[Purposes]The influence mechanisms of the tilt angle of a square cavity and Ra number on hy⁃brid nanoflow and heat transfer are studied.[Methods]Firstly,the combination of Adams-Bashforth and backward differentiation formula schemes,which is second-order-accurate and semi-implicit,is ad⁃opted to treat the temporal discretization.Secondly,the coupling of the velocity and the pressure is treated by using the improved projection scheme.Finally,all the governing equations are solved by using the collocation spectral method.[Findings]After the validation of numerical results,streamlines,iso⁃therms,and Nusselt number are analyzed for the effect of various parameters,for example,the inclination angle of the cavity(0≤θ≤π/4),and Rayleigh number(104≤Ra≤106).With the increasing of the inclination angle of the cavity,Nusselt number first increases and then drops.The fluid flow and heat transfer in⁃creases with the increasing of Rayleigh number.[Conclusions]The heat transfer is best when the inclina⁃tion angle of the cavity is equal toπ/6,and Rayleigh number is equal to 10^(6).