Dynamical transition and bifurcation of hydromagnetic convection in a rotating fluid layer

We study the stability and dynamic transition of a rotating electrically conducting fluid layer in the presence of an external magnetic field based on the Boussinesq approximation. By analyzing the spectrum of the linear part of the model and verifying the validity of the principle of exchange of stability, we take a hybrid approach combining theoretical analysis with numerical computation to study the transition from a simple real eigenvalue, a pair of complex conjugate eigenvalues and a real eigenvalue of multiplicity two, respectively. The center manifold reduction theory is applied to reduce the infinite dimensional system to the corresponding finite dimensional one together with several non-dimensional transition numbers that determine the dynamic transition types. Careful numerical computations are performed to determine these transition numbers as well as related flow patterns. Our results indicate that both continuous and jump transitions can occur at certain parameter region.