This paper presents the results of computational analysis of unsteady natural convection of a non-Newtonian fluid in an enclosure, taking into account the time sinusoidal dependence of the wall temperature. The analysis has been carried out to reveal the dependence of the emerging streamlines, isotherms, average Nusselt number and flow intensity on the controlling parameters such as Rayleigh number (Ra = 10⁴–10⁶), power-law index (n = 0.6–1.4), and side wall temperature oscillation frequency (f = 0.01π–0.05π). The problem has been worked out by the finite difference technique including the successive under-relaxation procedure, the locally one-dimensional Samarskii scheme, and the Thomas algorithm. The results show that a pseudoplastic fluid with high Rayleigh numbers and high oscillation frequencies is more suitable for intensifying the convective heat and mass transfer.

本文介绍了一个非牛顿流体在壳体中的非稳态自然对流的计算分析结果，同时考虑了壁温度对时间的正弦依赖性。已经进行了分析，揭示了新兴流线，等温线，平均努塞尔数和流动强度与控制参数（如瑞利数（Ra  = 10 ⁴ –10 ⁶），幂律指数（n  = 0.6- 1.4）和侧壁温度振荡频率（f = 0.01π–0.05π）。该问题已通过有限差分技术解决，包括连续欠松弛过程，局部一维Samarskii方案和Thomas算法。结果表明，具有较高瑞利数和较高振荡频率的假塑性流体更适合于增强对流换热和传质。