Abstract A mathematical model for mixed convection flow of a nanofluid along a vertical wavy surface has been studied. Numerical results reveal the effects of the volume fraction of nanoparticles, the axial distribution, the Richardson number, and the amplitude/wavelength ratio on the heat transfer of Al2O3-water nanofluid. By increasing the volume fraction of nanoparticles, the local Nusselt number and the thermal boundary layer increases significantly. In case of Ri = 1.0\mathrm{Ri}=1.0, the inclusion of 2 % and 5 % nanoparticles in the pure fluid augments the local Nusselt number, measured at the axial position 6.0, by 6.6 % and 16.3 % for a flat plate and by 5.9 % and 14.5 %, and 5.4 % and 13.3 % for the wavy surfaces with an amplitude/wavelength ratio of 0.1 and 0.2, respectively. However, when the Richardson number is increased, the local Nusselt number is found to increase but the thermal boundary layer decreases. For small values of the amplitude/wavelength ratio, the two harmonics pattern of the energy field cannot be detected by the local Nusselt number curve, however the isotherms clearly demonstrate this characteristic. The pressure leads to the first harmonic, and the buoyancy, diffusion, and inertia forces produce the second harmonic.

中文翻译：

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纳米流体对波纹表面混合对流增强传热的影响

摘要 研究了纳米流体沿垂直波浪面混合对流流动的数学模型。数值结果揭示了纳米颗粒的体积分数、轴向分布、理查森数和振幅/波长比对Al2O3-水纳米流体传热的影响。通过增加纳米粒子的体积分数，局部努塞尔数和热边界层显着增加。在 Ri = 1.0\mathrm{Ri}=1.0 的情况下，纯流体中包含 2 % 和 5 % 的纳米粒子会使在轴向位置 6.0 处测量的局部努塞尔数增加 6.6 % 和 16.3 %（对于平板）对于振幅/波长比分别为 0.1 和 0.2 的波状表面，分别为 5.9% 和 14.5%，以及 5.4% 和 13.3%。然而，当理查森数增加时，发现局部努塞尔数增加，但热边界层减少。对于较小的幅度/波长比值，局部努塞尔数曲线无法检测到能量场的二次谐波模式，但等温线清楚地证明了这一特性。压力导致一次谐波，浮力、扩散和惯性力产生二次谐波。