Sharif Digital Repository

A method for adaptive refinement of a triangular mesh for solution of the steady and unsteady Euler equations is presented. An upwind, finite volume based on Roe's flux difference splitting method is used to discretize the equations. By using advancing front method an initial regular Delaunay triangulation has been made. The adaptation procedures involve mesh enrichment and mesh coarsening to either add points in high gradient regions of the flow or remove points where they are not needed, respectively, to produce solutions of high spatial accuracy at minimal cost. Steady transonic results are shown to be of high spatial accuracy, primarily in that the shock waves are very sharply captured.... 

The main objective of this work is to develop a novel moving-mesh finite-volume method capable of solving the seepage problem in domains with arbitrary geometries. One major difficulty in analysing the seepage problem is the position of phreatic boundary which is unknown at the beginning of solution. In the current algorithm, we first choose an arbitrary solution domain with a hypothetical phreatic boundary and distribute the finite volumes therein. Then, we derive the conservative statement on a curvilinear co-ordinate system for each cell and implement the known boundary conditions all over the solution domain. Defining a consistency factor, the inconsistency between the hypothesis... 

Both the grid movement scheme and the moving grid solver are considered. A new grid movement scheme for large amplitude moving boundaries such as store separation has been developed. Some popular grid movement methods have been studied to analyse capabilities of this method. In fact, this scheme could be an optimal combination of the overset grids method and the local remeshing as it uses their advantages and avoids some of their disadvantages. To have valid solution in moving grids, two conservation laws, which preserve independences of solution from grid motions, have been considered. These constraints, which are called Geometric Conservation Laws (GCL), have been satisfied implicitly... 

The flow-induced oscillation (FIO) of bluff bodies is commonly encountered in the fluid structure interaction (FSI) problems. In this study, we use an unstructured moving grid strategy and simulate the FIO of two rigid plates, which are elastically hinged at the two ends of a fixed flat plate in a cross-flow. We use a hybrid finite-element-volume (FEV) method in an arbitrary Lagrangian–Eulerian (ALE) framework to study FIO of the two hinged plates. The current simulations are carried out for wide ranges of flow Reynolds number (50–175), spring stiffness coefficient, and the two hinged plates’ moment of inertia magnitudes. The influences of these parameters are investigated on the magnitudes... 

General purpose software is developed to simulate 6-DoF fluid-structure interaction in two-phase viscous flow. It is a VoF-fractional step solver based on the finite-volume discretization which uses a boundary-fitted body-attached hexahedral grid as the motion simulation strategy. As an application, a high-speed planing catamaran is simulated in steady forward motion as well as in turning maneuver. Results are compared with the available data and good qualitative and quantitative agreements are achieved. Numerical schemes and the solution algorithm of the software are consistent and show a good capability to model highly nonlinear ship motions. It can be further developed to represent a more...