THESIS
1999
x, 68 leaves : ill. ; 30 cm
Abstract
The coarsening dynamics for two-dimensional soap froth cellular network is studied experimentally by resistance measurements. The effective resistance of the froth changes as a result of changes in the cell boundaries. The changes due to the fast T1 processes are found to be much pronounced than the T2(3) processes. The change in resistance signal of a T1 process depends on the orientation of the T1 process with respect to the electrodes. Moreover, the relaxation time of T1 process is proportional to the coarsening time period and also depends on the wetness of the foam. Simple resistance network models are used to explain the experimental results. For the slow dynamics (diffusion mechanism), the resistance of two-dimensional soap froth cellular network is measured as the froth coarsens...[
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The coarsening dynamics for two-dimensional soap froth cellular network is studied experimentally by resistance measurements. The effective resistance of the froth changes as a result of changes in the cell boundaries. The changes due to the fast T1 processes are found to be much pronounced than the T2(3) processes. The change in resistance signal of a T1 process depends on the orientation of the T1 process with respect to the electrodes. Moreover, the relaxation time of T1 process is proportional to the coarsening time period and also depends on the wetness of the foam. Simple resistance network models are used to explain the experimental results. For the slow dynamics (diffusion mechanism), the resistance of two-dimensional soap froth cellular network is measured as the froth coarsens for different volume liquid fractions (wetness). The resistance is found to increase nonlinearly after a transient period. An iterative map using a substitution of simple resistor network is used to describe the experimental observation. The effective resistance of the resistor network is modeled using KirchhofI's current law on a scaled hexagonal network, where it is assumed that the mean area of bubbles is increasing linearly with time. The theoretical resistance as a function of time agrees well with the experimental results and the dependence of the resistance as a function of wetness can be understood within this simple model.
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