Numerical methods have been used extensively in modeling of free surface flows. These methods are generally classified into two categories; grid methods, and particles methods. In recent years, particle methods are gaining further attentions among numerical model developers for simulation of free surface flows. Computer simulation using particles has the capacity to analyze more complex geometry and physics than grid methods. Particularly, topological deformation of the fluid can be analyzed efficiently by particles, while it is hard and sometimes not possible to fit and move a grid continuously in such domains. Also, convection is directly calculated by the motion of particles without numerical diffusion. In addition, grid generation which recently seems to be used to analyze complex domains is not necessary, eliminating a significant portion of computational time. Although it is necessary to initialize configurations of particles in particle methods, this is much easier than grid generation as there is no need to set up topological relations among the particles. Problems with severe and sharp changes of free water surface can be simulated successfully with numerical methods based on the Lagrangian approach.
In this research the development of a numerical method based on the Lagrangian formulation to solve the Navier-Stokes equations is reported. Navier-Stokes equations are the governing equations of the fluids; a set of coupled partial differential equations that describe how the density, pressure, and velocity of a moving fluid are related. The Navier-Stokes equations are solved by the Moving Particle Semi Implicit (MPS) method, a mesh-free particle method. A fractional step method is applied which consists of splitting each time step in two steps. The fluid is represented with particles, and the motion of each particle is calculated based on the interactions with the neighboring particles covered by a kernel function.
In general, the contributions of this research can be categorized into three distinct parts: 1. Application of the MPS method is shown through the successful simulation of two sample complex free surface flows. Compared to the similar former studies focused on the application of this method, this research implements a newly-introduced kernel function. It is shown that by utilizing this new kernel function the stability of the simulations is significantly enhanced. 2. A multiphase MPS method is proposed for incompressible flows. The multiphase system is treated as a multi-density multi-viscosity fluid. A single set of governing equations is solved on the whole computational domain, and high-order accurate density and viscosity schemes are applied to stabilize the fluid pressure and shear stress fields. The proposed method is utilized for modeling of granular flows and sediment transport. 3. An algorithm is introduced to enhance the efficiency of the mesh-free particle methods. This algorithm enables the implementation of sets of particles with different sizes in one computational domain.
|Commitee:||Farhadi, Leila, Haque, Muhammad I., Manzari, Majid T., Riffat, Rumana|
|School:||The George Washington University|
|Department:||Civil and Environmental Engineering|
|School Location:||United States -- District of Columbia|
|Source:||MAI 55/02M(E), Masters Abstracts International|
|Subjects:||Mechanics, Civil engineering, Mechanical engineering|
|Keywords:||Computational efficiency, Free surface flow, Landslide, Mesh-free particle methods, Moving Particle Semi Implicit method, Multiphase flow|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be