Defect structures of Rayleigh-Benard travelling wave convection in binary fluid mixtures

Abstract

By using a twodimensional numerical simulation of the fully hydrodynamic equations, the dynamics of the traveling wave convection in binary fluid mixtures with defects was studied. For the separation ratio Ψ=-06, the system changes from localized traveling wave to traveling wave （TW） convection with the defects with increasing reduced Rayleigh number r. Then, the defects disappear and it changes to TW without defects with further increasing r. For different separation ratio Ψ, the periodicity of appearance of defects increases with reducing separation ratio and increasing r. The increase rate for a small negative separation ratio is larger than that for separation ratios. The range of existence of defects Δr remarkably decreases with the absolute value of Ψ. At Ψ=-011, the defects are annihilated and the TW with defects is not found. The system turns to the TW without defects from the TW with defects where r is larger than the upper limit of Δr. However, different values of Ψ correspond to different TW patterns when r is less than the lower limit of Δr. Therefore, it is obvious that the Ψ has influence on the pattern formation and on the transition between the patterns, and the transition between the patterns is also complex.