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Full-Text Articles in Physics

An Undular Bore Solution For The Higher-Order Korteweg-De Vries Equation, Tim Marchant Dec 2005

An Undular Bore Solution For The Higher-Order Korteweg-De Vries Equation, Tim Marchant

Tim Marchant

Undular bores describe the evolution and smoothing out of an initial step in mean height and are frequently observed in both oceanographic and meteorological applications. The undular bore solution for the higher-order Korteweg-de Vries (KdV) equation is derived, using an asymptotic transformation which relates the KdV equation and its higher-order counterpart. The higher-order KdV equation considered includes all possible third-order correction terms (where the KdV equation retains second-order terms). The asymptotic transformation is then applied to the KdV undular bore solution to obtain the higher-order undular bore. Examples of higher-order undular bores, describing both surface and internal waves, are presented. …


Solitary Wave Interaction And Evolution For A Higher-Order Hirota Equation, Tim Marchant Dec 2005

Solitary Wave Interaction And Evolution For A Higher-Order Hirota Equation, Tim Marchant

Tim Marchant

Solitary wave interaction and evolution for a higher-order Hirota equation is examined. The higher-order Hirota equation is asymptotically transformed to a higher-order member of the NLS hierarchy of integrable equations, if the higher-order coefficients satisfy a certain algebraic relationship. The transformation is used to derive higher-order one- and two-soliton solutions. It is shown that the interaction is asymptotically elastic and the higher-order corrections to the coordinate and phase shifts are derived. For the higher-order Hirota equation resonance occurs between the solitary waves and linear radiation, so soliton perturbation theory is used to determine the details of the evolving wave and …


Modelling A Wool Scour Bowl, Tim Marchant Dec 2005

Modelling A Wool Scour Bowl, Tim Marchant

Tim Marchant

Wool scouring is the process of washing dirty wool after shearing. Our model simulates, using the advection-diffusion equation, the movement of contaminants within a scour bowl. The effects of varying the important parameters are investigated. Interesting, but simple, relationships are found which give insight into the dynamics of a scour bowl.