Stability of triple diffusive convection in a viscoelastic fluid-saturated porous layer  

作　　者：K.R.RAGHUNATHA I.S.SHIVAKUMARA 

机构地区：[1]Department of Mathematics, Bangalore University

出　　处：《Applied Mathematics and Mechanics(English Edition)》2018年第10期1385-1410,共26页应用数学和力学（英文版）

基　　金：supported by the Innovation in Science Pursuit for the Inspired Research(INSPIRE)Program(No.DST/INSPIRE Fellowship/[IF 150253])

摘　　要：The triple diffusive convection in an Oldroyd-B fluid-saturated porous layer is investigated by performing linear and weakly nonlinear stability analyses. The condition for the onset of stationary and oscillatory is derived analytically. Contrary to the observed phenomenon in Newtonian fluids, the presence of viscoelasticity of the fluid is to degenerate the quasiperiodic bifurcation from the steady quiescent state. Under certain conditions, it is found that disconnected closed convex oscillatory neutral curves occur, indicating the requirement of three critical values of the thermal Darcy-Rayleigh number to identify the linear instability criteria instead of the usual single value, which is a novel result enunciated from the present study for an Oldroyd-B fluid saturating a porous medium. The similarities and differences of linear instability characteristics of Oldroyd-B, Maxwell, and Newtonian fluids are also highlighted. The stability of oscillatory finite amplitude convection is discussed by deriving a cubic Landau equation,and the convective heat and mass transfer are analyzed for different values of physical parameters.The triple diffusive convection in an Oldroyd-B fluid-saturated porous layer is investigated by performing linear and weakly nonlinear stability analyses. The condition for the onset of stationary and oscillatory is derived analytically. Contrary to the observed phenomenon in Newtonian fluids, the presence of viscoelasticity of the fluid is to degenerate the quasiperiodic bifurcation from the steady quiescent state. Under certain conditions, it is found that disconnected closed convex oscillatory neutral curves occur, indicating the requirement of three critical values of the thermal Darcy-Rayleigh number to identify the linear instability criteria instead of the usual single value, which is a novel result enunciated from the present study for an Oldroyd-B fluid saturating a porous medium. The similarities and differences of linear instability characteristics of Oldroyd-B, Maxwell, and Newtonian fluids are also highlighted. The stability of oscillatory finite amplitude convection is discussed by deriving a cubic Landau equation,and the convective heat and mass transfer are analyzed for different values of physical parameters.

关 键 词：Oldroyd-B fluid BIFURCATION INSTABILITY perturbation method nonlinear stability heat and mass transfer 

分 类 号：O357.3[理学—流体力学] O175.8[理学—力学]