Numerical simulation of internal fluidisation and cavity evolution due to a leaking pipe using the coupled DEM-LBM technique

Cui, Xilin (2013). Numerical simulation of internal fluidisation and cavity evolution due to a leaking pipe using the coupled DEM-LBM technique. University of Birmingham. Ph.D.

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Abstract

Motivated by internal fluidisation due to a leaking pipe, this thesis aims to achieve a deeper understanding of the leakage-soil interaction by numerical simulations. The coupled DEM (Discrete Element Method) – LBM (Lattice Boltzmann Method) technique has been regarded as a promising tool to efficiently provide detailed description of fluid-particle systems, especially with intensive fluid-particle interactions. Therefore, FPS-BHAM, a 2D DEM-LBM computer code is developed for this thesis. In this code, DEM models the soil as an assembly of circular particles, and LBM is employed for fluid flow simulations. The Immersed Moving Boundary (IMB) scheme is adopted for the treatment of fluid-particle interaction.

Numerical results are validated against existing experimental findings. Different regimes of bed behaviour are demonstrated under various flow rates. The onset of fluidisation is studied by analytically deriving for the flow equation and fluidising pressure, which are compared with numerical solutions. Moreover, deeper insights are made into the post-fluidisation phenomenon. The mechanism underlying a stable cavity is explored, and how a cavity evolves with different factors is also investigated through parametric studies.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):