The concept of nonlinear thermal convection is taking place for the process of cooling/heating in some thermal industries like solar collectors, combustion, and reactor safety. The significance of linear and nonlinear thermal convection is implemented in the present mathematical modeling to handle nonlinear density-temperature caused by viscous dissipation and flow through a porous medium. Further, the inclined magnetic field is implemented to analyze the flow characteristic at various inclination angles which will be helpful in glass manufacturing, geophysics, crude oil purification, and paper production. Furthermore, entropy generation analysis is made for the stagnation point flow of viscous fluid over a shrinking Riga sheet. Using boundary layer assumptions, the present model made up of fluid motion and energy equations is formed and converted to a system of nonlinear differential equations. Numerical results are collected using the MATLAB bvp4c solver and these results were utilized to study important parameters on the entropy generation and heat transport of fluid flow. The presence of nonlinear thermal convection will intensify the impact of major parameters and the least entropy generated for the inclination angle of the magnetic field. Also, entropy enhanced significantly with the Eckert number and modified Hartmann number. In addition, the surface drag is enhanced by 12%-18 % and the thermal transmission rate is diminished by 4%-7% in the case of nonlinear thermal convection compared to the linear case. The findings of this study are more important to optimize heat transfer and irreversibility in the applications of the automotive industry, ceramics, paints, food packaging, fabrics, pharmaceuticals, and cancer treatment.

中文翻译：

---

沿收缩里加片磁化耗散流非线性热对流与熵产生的比较研究

非线性热对流的概念正在应用于太阳能集热器、燃烧和反应堆安全等一些热工业的冷却/加热过程中。线性和非线性热对流的重要性在当前的数学模型中得到实现，以处理由粘性耗散和流经多孔介质引起的非线性密度-温度。此外，还利用倾斜磁场来分析不同倾斜角度下的流动特性，这将有助于玻璃制造、地球物理、原油净化和造纸等领域。此外，对收缩的里加片上粘性流体的驻点流进行了熵产生分析。使用边界层假设，形成由流体运动和能量方程组成的当前模型，并将其转换为非线性微分方程组。使用 MATLAB bvp4c 求解器收集数值结果，并利用这些结果来研究流体流动的熵产生和传热的重要参数。非线性热对流的存在会加剧主要参数和磁场倾角产生的最小熵的影响。此外，埃克特数和修正哈特曼数的熵显着增强。此外，与线性情况相比，非线性热对流情况下的表面阻力增加了12%-18%，热传导率减少了4%-7%。这项研究的结果对于优化汽车工业、陶瓷、油漆、食品包装、织物、药品和癌症治疗应用中的传热和不可逆性更为重要。