关键词: 热对流, 磁场, 双层系统, 黏弹性流体, Chebyshev配点法

Abstract: The author investigated the thermal convection flow of Oldroyd-B fluids in a fluid-porous medium two-layer system heated from below, and analyzed the effects of viscoelastic properties of the Oldroyd-B fluid on oscillatory instabilities and its dominant branches under a vertical magnetic field. It was assumed that the flow in the porous medium was controlled by a modified Darcy’s law, and the boundaries were subject to isothermal conditions. Linear stability analysis of the control equations was conducted, and neutral curves for different parameters were obtained by using the Chebyshev collocation method. The results show that the effects of the thickness ratio and Chandrasekhar number on convective stability are opposite, and increasing the thickness ratio can gradually diminish the bimodal characteristics of the neutral curve. Additionally, as the magnetic field intensity increases, the start time of oscillatory convection is delayed, and the convective dominant branch shifts from short-wave branch to long-wave branch. After the conversion, the effect of magnetic field intensity on thermal convection stability is relatively small.

Key words: thermal convection, magnetic field, two-layer system, viscoelastic fluid, Chebyshev collocation method