Hakan Akyildiz

NONLINEAR MODELING OF LIQUID SLOSHING IN A MOVING RECTANGULAR TANK

Abstract A nonlinear liquid sloshing inside a partially filled rectangular tank has been investigated. The fluid is assumed to be homogeneous, isotropic, viscous, Newtonian and exhibit only limited compressibility. The tank is forced to move harmonically along a vertical curve with rolling motion to simulate the actual tank excitation. The volume of fluid technique is used to track the free surface. The model solves the complete Navier–Stokes equations in primitive variables by use of the finite difference approximations. At each time step, a donor–acceptor method is used to transport the volume of fluid function and hence the locations of the free surface. In order to assess the accuracy of the method used, computations are verified through convergence tests and compared with the theoretical solutions and experimental results.

Experimental investigation of pressure distribution on a cylinder due to the wave diffraction in a finite water depth

The experimental investigations on the pressure distribution around a large vertical cylinder fixed on a wave channel, piercing the free surface and subjected to regular waves have been carried out. Recently, considerable advances have been made in the development of analytical techniques for studying non-linear wave loading phenomena on large structures. However, there is a lack of high quality experimental data that may be used for validating the analytical and numerical solutions obtained. This paper describes the design and execution of an experiment conducted at the Hydraulics Laboratory in the Civil Engineering Department of the Istanbul Technical University. Experimental measurements of pressures at different locations are presented including comparisons with the computational results. This study showed that the experimental and computational results generally exhibited better correlation, however, the measured pressure values diverged from the computational results while approaching the free surface.

Formal Safety Assessment of Cargo Ships at Coasts and Open Seas of Turkey

This paper presents an evaluation of Formal Safety Assessment framework for cargo ships at coasts and open seas of Turkey. Based on Turkish Under secretariat of Maritime Affairs casualty reports, this study identifies risk factors that have significant, independent effects upon the likelihood of ship and offshore operations. A case study is carried out to determine the most common causes of unintentional damages on cargo ships using FSA. It is obvious that shortage of skilled crew and crew training become very important for safety. This would require a compulsory course related to the human functions such as knowledge of regulations and use of equipment. Finally, some conclusions and suggestions are drawn concerning the needs to reduce the risks and to improve certain safety measures at coasts and open seas of Turkey.Copyright