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87 ISSN 2086-5953 SMOOTHED PARTICLE HYDRODYNAMIC MODEL FOR DAM BREAK PROBLEM WITH OBSTACLE AND OBSTACLE-CLEARANCE Syamsuri 1 , Tungga Bhimadi 2 , Junaidillah Fadlil 3 1 Department of Mechanical Engineering National Taiwan University of Science and Technology 2 Department of Naval Engineering Sepuluh Nopember Institute of Technology 3 Department of Computer Science and Information Engineering National Taiwan University of Science and Technology Email: syam_sby2003yahoo.com 1 ABSTRACT Dam break flow has been the subject of intensive research for a long time. Dam break flow includes several features of existing problems in the area of fluid mechanics, environment protection, marine hydrodynamics, and coastal engineering. Dam break flow is widely used as a classical test case for numerical simulation of free surface and moving boundary. Solutions are accomplished with Smoothed Particle Hydrodynamics SPH technique using a pc cluster. For dam break flow impact against the obstacle, the flow impacts on the vertical wall at t = 0.8 sec, at time t = 1.2 sec an upward water jet is suddenly formed and over- turning wave with an adverse momentum is observed at t = 1.3 sec. Impact pressure flow on a wall of the obstacle is 2.39 Nm2 and velocity in y direction is 4.32 msec. Regarding dam break flow impact against obstacle-clearance, high velocity and shallow water depth flow are happened in x- direction at t = 0.35 sec. The two flow face each other and this two flow impact the vertical flow then simulate a splash. This happened at t = 1.1 sec. The established SPH model is able to capture over- turning wave phenomena and splash phenomena. Keywords: Dam Break, Smoothed Particle Hydrodynamics, Obstacle, Obstacle-clearance.  1 INTRODUCTION

1.1 Motivation

The dam break problem was approached mathematically by Stoker [10]. For studying green water loads on ships, this problem was investigated experimentally by Zhou et al. [12]. The dam break flow with the consequent wall impact is widely used to benchmark various numerical techniques that tend to simulate interfacial flows and impact problems see e.g. [2, 3]. This is due to the fact that this problem includes several features of existing problems in the area of marine hydrodynamics and coastal engineering. For example, in a shipping of water event, the problem includes: wave run-up on the ship bow; formation of a water height above the deck dam formation; high velocity shallow water flow dam break; and impact of the flow on deck mounted structures impact to the vertical wall [3]. Therefore, the impact flow on a wall resulting from a dam break problem has scientific and practical importance. As far we know, for a dam break with an obstacle in the middle and for a dam break with obstacle and clearance in the middle using SPH model have never been considered.

1.2 Problem Definition

Smoothed Particle Hydrodynamics SPH was developed and have been launched by various research teams e.q. SPH European Research Interest Community or SPHERIC in association with industry. SPH can simulate various phenomena including wave breaking, dam break, sliding objects, wave impact on a structure, etc. Many international journal paper regarding SPH results have been published [4, 5 11]. This paper presents a numerical method based on Smoothed Particle Hydrodynamics SPH method and offers the possibility among other applications to describe accurately the impact flow when water is facing an obstacle and when water are facing a clearance. The first case is a dam break with obstacle in the middle. The purpose of the case is to understand the detail phenomena of a fluid when the fluid across the obstacle. Depending on the special circumstances different characteristic features are ISSN 2086-5953 observed. The second case study, however, aims to show the clearance phenomena when the water enter the clearance of the obstacle. 2 METHOD VALIDATION

2.1 Methods of SPH