Experimental Evidence on the Structure and Evolution of the penta-Hepta Defect in Hexagonal Lattices due to BéNard-Marangoni convection

Evidence is provided to show that the penta–hepta defect in a Benard convective hexagonal lattice arises as a result of the attraction of two dislocations having opposite topological charges and belonging to different modes. The dislocations approach each other along a corridor connecting those topological charges. Fields of long–living penta–hepta defects have been analyzed. The comparison of experimental results with recent numerical calculations and solutions obtained analytically shows good qualitative agreement.

[1]  Structure of dislocations in the hexagonal pattern , 1993 .

[2]  Experimental studies of defect dynamics and interaction in electrohydrodynamic convection. , 1990, Physical review. A, Atomic, molecular, and optical physics.

[3]  Ahlers,et al.  Transitions between patterns in thermal convection. , 1991, Physical review letters.

[4]  E. Koschmieder,et al.  Bénard cells and Taylor vortices , 1993 .

[5]  R. D. Vigil,et al.  Turing patterns in a simple gel reactor , 1992 .

[6]  M. Cross,et al.  Pattern formation outside of equilibrium , 1993 .

[7]  Tsimring,et al.  Dynamics of dislocations in hexagonal patterns. , 1994, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[8]  Ciliberto,et al.  Defects in roll-hexagon competition. , 1990, Physical review letters.

[9]  Ciliberto,et al.  Competition between different symmetries in convective patterns. , 1988, Physical review letters.

[10]  Jean Bragard,et al.  Bénard–Marangoni convection: planforms and related theoretical predictions , 1998, Journal of Fluid Mechanics.

[11]  G. Ahlers,et al.  Non-Boussinesq and penetrative convection in a cylindrical cell , 1981, Journal of Fluid Mechanics.

[12]  Perez-Garcia,et al.  Wavelength selection in Bénard-Marangoni convection. , 1987, Physical review. A, General physics.