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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Homogenized Equations for Isothermal Gas in a Pipe with Periodically-Varying Cross-Section

Busaleh, Laila 08 1900 (has links)
Shocks form in the solutions of first-order nonlinear hyperbolic PDEs with constant co-efficients. Where solitary waves arise in the solutions of first-order nonlinear hyperbolic PDEs with variable coefficients, those solitary waves occur due to the coupling of nonlinearity and dispersive effects that comes from the medium’s heterogeneity. In this thesis, we study a fluid that propagates in a narrow pipe with periodically-varying cross-sectional area described by a system of first-order nonlinear hyperbolic PDEs. Multiple-scale perturbation theory is applied to derive homogenized effective equations, which take the form of a constant-coefficient system including higher-order dispersive terms. We investigate the behavior of the solution by deriving the linear dispersion relation of the homogenized system. The homogenized equations are solved using a psuedospectral discretization in space and explicit Runge-Kutta method in time. Lastly, we develop a Riemann solver in Clawpack to solve the variable coefficients system and compare the obtained solution with the homogenized equations solution.

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