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Influence of temperature dependent viscosity and internal heating on the onset of convection in porous enclosures saturated with viscoelastic fluid
Asia-Pacific Journal of Chemical Engineering ( IF 1.8 ) Pub Date : 2020-05-26 , DOI: 10.1002/apj.2514
Dhananjay Yadav 1 , Manal Maqhusi 1
Affiliation  

The combined influence of temperature dependent viscosity and internal heat source on the onset of convection in porous enclosures saturated by a viscoelastic fluid is studied using linear and weak nonlinear stability theories. The enclosures are taken to be rectangular, square, and slender. For the viscoelastic fluid, the Oldroyd‐B type model is used, whereas the Darcy's model is taken for porous medium. The linear theory based on normal mode technique is used to find the criteria for the onset of marginal and oscillatory convections, and weakly nonlinear analysis based on minimal representation of truncated Fourier series is considered to discuss the convective heat transport in the system. It is observed that the beginning of convection will be oscillatory only if the strain retardation parameter is not greater than the stress relaxation parameter. The influence of raising the viscosity variation parameter, the internal heating parameter, and the stress relaxation parameter is to fast the onset of convection and also boost the heat transmission through the porous enclosures, but an opposite tendency is identified by raising the strain retardation parameter and the heat capacity ratio. The heat transmission decreases with the aspect ratio for rectangular enclosure, whereas this outcome is revered for the slender enclosure.

中文翻译:

温度依赖性粘度和内部加热对粘弹性流体饱和的多孔罩中对流开始的影响

利用线性和弱非线性稳定性理论研究了温度依赖性粘度和内部热源对被粘弹性流体饱和的多孔围护结构中对流开始的综合影响。外壳取为矩形,正方形和细长形。对于粘弹性流体,使用Oldroyd-B型模型,而对于多孔介质则采用Darcy模型。利用基于正态模式技术的线性理论来寻找边缘对流和振荡对流的发生准则,并考虑基于截短傅立叶级数最小表示的弱非线性分析来讨论系统中的对流传热。可以看出,仅当应变延迟参数不大于应力松弛参数时,对流的开始才是振荡的。升高粘度变化参数,内部加热参数和应力松弛参数的影响是加快对流的开始并促进通过多孔外壳的传热,但通过增加应变延迟参数和降低应变率可以确定相反的趋势。热容比。对于矩形外壳,传热会随着长宽比的增加而降低,而对于细长的外壳,这种结果得到了认可。应力松弛参数是为了加快对流的开始并增加通过多孔外壳的热传递,但是通过提高应变延迟参数和热容比可以发现相反的趋势。对于矩形外壳,传热会随着长宽比的增加而降低,而对于细长的外壳,这种结果得到了认可。应力松弛参数是为了加快对流的开始并增加通过多孔外壳的热传递,但是通过提高应变延迟参数和热容比可以发现相反的趋势。对于矩形外壳,传热会随着长宽比的增加而降低,而对于细长的外壳,这种结果得到了认可。
更新日期:2020-05-26
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