This work reports the effects of magnetic field on an electrically conducting fluid with low electrical conductivity flowing in a smooth expanded channel. The governing nonlinear magnetohydrodynamic （MHD） equations ...This work reports the effects of magnetic field on an electrically conducting fluid with low electrical conductivity flowing in a smooth expanded channel. The governing nonlinear magnetohydrodynamic （MHD） equations in induction- free situations are derived in the framework of MHD approximations and solved numerically using the finite-difference technique. The critical values of Reynolds number （based on upstream mean velocity and channel height） for symmetry breaking bifurcation for a sudden expansion channel （1：4） is about 36, whereas the value in the case of the smooth expansion geometry used in this work is obtained as 298, approximately （non-magnetic case）. The flow of an electrically conducting fluid in the presence of an externally applied constant magnetic field perpendicular to the plane of the flow is reduced significantly depending on the magnetic parameter （M）. It is expansion （1：4） is about 475 for the magnetic parameter M found that the critical value of Reynolds number for smooth = 2. The separating regions developed behind the smooth symmetric expansion are decreased in length for increasing values of the magnetic parameter. The bifurcation diagram is shown for a symmetric smoothly expanding channel. It is noted that the critical values of Reynolds number increase with increasing magnetic field strength.展开更多
The existence and stability ol periodic solutions for the two-dimensional system x' = f(x)+?g(x ,a), 0<ε<<1 ,a?R whose unperturbed systemis Hamiltonian can be decided by using the signs of Melnikov's...The existence and stability ol periodic solutions for the two-dimensional system x' = f(x)+?g(x ,a), 0<ε<<1 ,a?R whose unperturbed systemis Hamiltonian can be decided by using the signs of Melnikov's function. The results can be applied to the construction of phase portraits in the bifurcation set of codimension two bifurcations of flows with doublezero eigenvalues.展开更多
A linear stability analysis is performed for a plume flow inside a cylinder of aspect ratio 1. The configu- ration is identical to that used by Lopez and Marques （2013） for their direct numerical simulation study, I...A linear stability analysis is performed for a plume flow inside a cylinder of aspect ratio 1. The configu- ration is identical to that used by Lopez and Marques （2013） for their direct numerical simulation study, It is found that the first bifurcation, which leads to a periodic axisymmetric flow state, is accurately pre- dicted by linear analysis： both the critical Rayleigh number and the global frequency are consistent with the reported DNS results. It is further shown that pressure feedback drives the global mode, rather than absolute instability.展开更多
基金support by the UGC(SAP),DSA-I in the Mathematics Department,Burdwan University,India
文摘This work reports the effects of magnetic field on an electrically conducting fluid with low electrical conductivity flowing in a smooth expanded channel. The governing nonlinear magnetohydrodynamic （MHD） equations in induction- free situations are derived in the framework of MHD approximations and solved numerically using the finite-difference technique. The critical values of Reynolds number （based on upstream mean velocity and channel height） for symmetry breaking bifurcation for a sudden expansion channel （1：4） is about 36, whereas the value in the case of the smooth expansion geometry used in this work is obtained as 298, approximately （non-magnetic case）. The flow of an electrically conducting fluid in the presence of an externally applied constant magnetic field perpendicular to the plane of the flow is reduced significantly depending on the magnetic parameter （M）. It is expansion （1：4） is about 475 for the magnetic parameter M found that the critical value of Reynolds number for smooth = 2. The separating regions developed behind the smooth symmetric expansion are decreased in length for increasing values of the magnetic parameter. The bifurcation diagram is shown for a symmetric smoothly expanding channel. It is noted that the critical values of Reynolds number increase with increasing magnetic field strength.
基金The project is supported by the National Natural Science Foundation of China
文摘The existence and stability ol periodic solutions for the two-dimensional system x' = f(x)+?g(x ,a), 0<ε<<1 ,a?R whose unperturbed systemis Hamiltonian can be decided by using the signs of Melnikov's function. The results can be applied to the construction of phase portraits in the bifurcation set of codimension two bifurcations of flows with doublezero eigenvalues.
基金provided by the Agence Nationale de la Recherche under the "Cool Jazz" project
文摘A linear stability analysis is performed for a plume flow inside a cylinder of aspect ratio 1. The configu- ration is identical to that used by Lopez and Marques （2013） for their direct numerical simulation study, It is found that the first bifurcation, which leads to a periodic axisymmetric flow state, is accurately pre- dicted by linear analysis： both the critical Rayleigh number and the global frequency are consistent with the reported DNS results. It is further shown that pressure feedback drives the global mode, rather than absolute instability.
