Department of Physics, Faculty of Sciences, University of Tabuk, Tabuk, Saudi Arabia.
Renewable Energy & Environmental Technologies Research Center, University of Tabuk, Tabuk, Saudi Arabia.
PLoS One. 2024 Jun 20;19(6):e0304685. doi: 10.1371/journal.pone.0304685. eCollection 2024.
The nonlinear effects of thermal radiation on the free convection flow of certain nanofluids along a heated wall are studied numerically using an original finite-difference method. Nanofluids are used to improve the performance of flat and curved integrated photovoltaic modules. The partial differential equations governing the flow are difficult to solve due to the strong non-linearity of the radiative term. In contrast to previous studies, the problem is solved directly without linearization by Rosseland's nonlinear approximation. The proposed numerical method is validated with results from the literature. The effects of nonlinearity and various physical parameters such as time, volume fraction and radiation parameter on the velocity, temperature, Nusselt number and skin friction coefficient of the CuO-water nanofluid are analyzed and presented graphically. A comparative study between the solutions given by the linear and non-linear problems reveals that Rosseland's linear approximation is no longer valid when the effect of thermal radiation is significant. On the other hand, the non-linear model better reflects the physical phenomena involved in the cooling process. Finally, a comparison of the performance of five nanofluids (CuO, Ag, Al2O3, Cu and TiO2 in water) shows that the Cu-water nanofluid performs best, with a high heat transfer rate and low shear stresses.
采用原始有限差分法数值研究了热辐射对沿加热壁的某些纳米流体自由对流流动的非线性影响。纳米流体被用于提高平板和曲面集成光伏模块的性能。由于辐射项的强非线性，控制流动的偏微分方程难以求解。与先前的研究不同，该问题通过罗塞尔非线性逼近直接求解而无需线性化。所提出的数值方法通过文献中的结果进行了验证。分析了非线性和各种物理参数（如时间、体积分数和辐射参数）对 CuO-水纳米流体的速度、温度、努塞尔数和壁面摩擦系数的影响，并以图形方式表示。线性和非线性问题给出的解之间的比较研究表明，当热辐射的影响显著时，罗塞尔的线性近似不再有效。另一方面，非线性模型更好地反映了冷却过程中涉及的物理现象。最后，对五种纳米流体（CuO、Ag、Al2O3、Cu 和 TiO2 在水中）的性能进行了比较，结果表明 Cu-水纳米流体的性能最佳，具有较高的传热率和较低的剪切应力。
