Unsteady Friction Modeling Technique for Lagrangian Approaches in Transient Simulations

Abstract

This study investigates the simulation of celerity attenuation and head damping in transient flows using a Lagrangian approach rather than an Eulerian approach. Typically, the Lagrangian approach requires orders of magnitude fewer calculations, resulting in the rapid solution of very large systems. Additionally, it is based on a simple physical model. As the method is continuous in both time and space, it is less sensitive to the structure of the network and the length of the simulation process. Most recent studies, however, have focused on the development and improvement of computational routines for modeling in an Eulerian environment. This results in the development of adequate models that are suitable for Eulerian models but not applicable in Lagrangian-based models. As a result of this fixation, a bias was created towards using Eulerian approaches in transient simulations. It also diverts resources from further development of Lagrangian models. Consequently, it is necessary to develop a friction model that is more accurate and compatible with Lagrangian methods without compromising their performance. To the authors’ knowledge, such a model is yet to be published in the literature. This study presents a new friction modeling technique that compensates for both the local and convective acceleration terms for the Lagrangian transient modeling approach without compromising the computational time.