| The goal of this research is to understand domain coarsening behavior in anisotropic pattern forming systems. While uniform systems are widely studied theoretically and experimentally, coarsening dynamics in striped system is less understood. In this thesis, our focus is to study topological defect motions as a probe to understand domain growth in striped systems. Three experimental results are reported in this thesis.; Ch. 4 describes the impacts of wavenumbers in coarsening dynamics. A series of quenches with various modulated frequencies is applied to the travelling pattern. The resulting striped standing pattern is varied to have various values of the average wavenumber in the background. The results exhibit a complex dynamics of domain coarsening under an influence of modulated frequencies. Using total wall length, L as a scaling variable, the exponents were measured. The exponents range from 0.25 to 0.6. Experiments in shows complex dynamics of background average wavenumber and measurements of domain sizes.; In Ch. 5, N4 liquid crystals were used for electroconvection. The pattern has two oblique rolls, zig and zag. Two different types of domain walls are observed: a regular grain boundary and a wall consisting of dislocations. Regular grain boundaries form parallel to the direction of director. Walls of dislocations form perpendicular to director. We observe dislocation dynamics contributing to the domain coarsening dynamics. In the late time of coarsening, dislocations moving parallel to the direction of director annihilate with each other. This dynamics result in anisotropic coarsening behavior. This experiment motivated us to conduct further experiments for understanding of dislocation dynamics.; Ch. 6 is a report on the experimental results of outlining domain growth affected by two different quench depths. In Ch. 6, numbers of dislocations and the total domain walls were measured with two different quench values, &egr; = 0.02 and &egr; = 0.05. For a smaller quench value &egr; = 0.02, both numbers of dislocations and total domain walls decrease monotonically, though the images taken at the end of experiment does not show that the domains have coarsened to the maximum size. For a bigger quench depth &egr; = 0.05, numbers of dislocations and total domain walls do not decrease. Two measurements suggest the possible pinning effect in the striped system. Though further work is required, results reported in Ch. 6 agree with the simulation [1]. |
