Dynamics of extensible pipes conveying fluid: an approach via Analytical Mechanics

Abstract

The dynamic behavior introduced by internal flow in flexible pipe is an essential problem of Fluid-Structure Interactions (FSI). It characterizes an open system, in which Mechanical formulations must include terms related to material transport so that a precise mathematical modeling can be executed. In the master's thesis, the candidate worked with bidimensional nonlinear models of extensible pipes conveying fluid, in which the fundamental conditions of mass conservation are respected. It was possible to demonstrate, in an unprecedented way, the influence of transport of kinetic energy term on the pipe dynamics, which was identically null in inextensible formulations under the assumption of plug flow. Furthermore, a set of models was derived using the Modular Modeling Methodology, which algebraically simplifies the deduction of equations of motion. The present research proposes to extend the extensible models to three dimensions, the incorporation of aspiration regimes and the consideration of complementary effects associated with the external flow. The modeling will also be guided by experimental results obtained by the Offshore Mechanics Laboratory team. The aim is to elaborate a parametric study on the influence of extensibility, making it possible to identify scenarios in which this hypothesis significantly affects the dynamics of the system. In addition to the original theoretical-conceptual development, such models make it possible to advance studies in the area of offshore oil exploration, in the global dynamics of Seawater Intake Risers and in the simulation of excavation hoses in salt caverns, using the strong instability of ejection regimes.