Numerical investigation of free surface and pipe flow problems by smoothed particle hydrodynamics


Thesis Type: Doctorate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Civil Engineering, Turkey

Approval Date: 2017

Student: ALİ ERSİN DİNÇER

Supervisor: ZAFER BOZKUŞ

Abstract:

In the present study, a two-dimensional (2D) computer code for free surface and pipe flows is developed by using Smoothed Particle Hydrodynamics (SPH) approach. For free surface flow problem, idealized dam break problems are investigated numerically. The results of three recently published experimental studies are used to validate the numerical solutions. In addition to mesh-free particle method, SPH with a novel boundary treatment model proposed in the present study, mesh-based methods with turbulence and laminar modelling are used to simulate the dam break problem. It is confirmed that SPH can be used to predict the behavior of dam-break induced flows. In addition, the computational time of SPH decreases with the proposed boundary model which is seminal for fluid-structure interaction problems with SPH. Liquid slug flow driven by pressurized air in inclined and horizontal pipes with a downstream elbow is investigated numerically for the application of SPH in pipe flows. As the liquid slug hits the elbow, the impact pressure and the associated force generated at the elbow may damage pipe supports as well as the pipe itself. The slug arrival velocity and slug length (i.e. mass) at the elbow directly affect that pressure. In order to calculate these slug parameters just before the impact an improved one-dimensional (1D) model proposed in the literature is used. At the elbow, pressure variation with respect to time is calculated with SPH. The obtained numerical data are validated with previously published experimental results. For both short and long slugs, calculated peak pressures and pressure variations show great agreement with those of measured peak pressures and pressure variations.