Author(s): Alexandre Soares; Iago Q. Silva; Joel R. G. Vasco
Linked Author(s): Alexandre Soares
Keywords: Hydraulic transients; MOC; SPH; Meshfree methods; Artificial viscosity; Sensitivity analysis
Abstract: Hydraulic transients are phenomena that occur when the conditions of a flow, such as pressure and velocity, change with time. This regime is governed by hyperbolic partial differential equations (PDEs), for which there is no explicit solution. Therefore, it is necessary to use numerical methods, amongst which the method of characteristics (MOC) stands out. The MOC uses a characteristic grid to transform the PDEs into ordinary differential equations (ODEs) and, after that, into explicit equations. However, methods that use grids may present some problems, especially when there are complex geometries and deformable contours. To solve these problems, there are methods that don’t use grids (meshfree), amongst which the smoothed particle hydrodynamics (SPH) stands out. This method was initially conceived in the seventies to solve astrophysical problems and, briefly, it allows that a function and its derivatives may be represented by an approximation. To apply it to a hydraulic transient, it is necessary to make an adaption by considering a term known as artificial viscosity, besides using a temporal integration method. In this paper, in order to verify the efficiency of methods with or without grids, a hydraulic transient was simulated using MOC and a modified version of SPH, known as corrective smoothed particle method (CSPM). The results showed that CSPM produces values that are compatible with MOC, although there are little divergences as the simulation runs. Besides, a sensitivity analysis showed that simulations with higher number of particles provide more accurate results in CSPM.
Year: 2025