论文标题
Ellis流体的雷利 - 贝纳德不稳定饱和多孔培养基
Rayleigh-Bénard instability of an Ellis fluid saturating a porous medium
论文作者
论文摘要
与幂律模型不同，埃利斯模型描述了剪切稀释的液体的明显粘度，在消失的小剪切应力的极限下没有奇异性。特别是，当剪切应力很小时，该模型与牛顿行为相匹配。当水平压力梯度在水平多孔层中开出了基本的遍布时，研究了雷利 - 贝纳德不稳定性的出现。该系统线性不稳定性的阈值条件在分析和数值上均可获得。在流速可忽略不计的情况下，对于在文献中报告的相同参数条件下，不稳定性的发作发生在纳入多孔培养基的牛顿流体中。另一方面，当考虑高流速时，在整个水平边界上施加的温度差异很小，足以触发对流的不稳定性。
Unlike the power-law model, the Ellis model describes the apparent viscosity of a shear-thinning fluid with no singularity in the limit of a vanishingly small shear stress. In particular, this model matches the Newtonian behaviour when the shear stresses are very small. The emergence of the Rayleigh-Bénard instability is studied when a horizontal pressure gradient, yielding a basic throughflow, is prescribed in a horizontal porous layer. The threshold conditions for the linear instability of this system are obtained both analytically and numerically. In the case of a negligible flow rate, the onset of the instability occurs for the same parametric conditions reported in the literature for a Newtonian fluid saturating a porous medium. On the other hand, when high flow rates are considered, a negligibly small temperature difference imposed across the horizontal boundaries is sufficient to trigger the convective instability.
