Browsing by Author "AKAY, Hasan"
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Item A phenomenological study of instructors’ experiences on an open source learning management system(Procedia - Social and Behavioral Sciences, 2011-08-08) ÇİĞDEMOĞLU, Ceyhan; ARSLAN, Harika Özge; AKAY, HasanThis paper focuses on instructors’ experiences on usage of an open-source Learning Management System (LMS), Moodle in their courses. The study was conducted in a private university in Ankara, Turkey where the widespread use of the Moodle has only recently started. The phenomenological design has been utilized as qualitative research method for this paper. The Participants comprised in structures from different faculties who are new users of the Moodle. Open-ended interviews were carried out, and the data was transcribed into codes and themes. The research findings indicate that instructors have different impressions from the system in terms of their effort and expectation.Item SOLUTION OF STORE SEPARATION PROBLEMS USING OPENFOAM(2022-03-12) ABUHANIEH, Saleh; AKAY, HasanIn this thesis, the ability of OpenFOAM to solve the store separating from an air ve hicle (store separation problem) using a dynamic mesh (Overset/Chimera) technique for an industry-class (transonic/supersonic and generic) benchmark test case has been evaluated and improved. The major limitations of the standard libraries have been determined. To tackle these challenges, a new strategy has been proposed and imple mented using only open-source libraries and tools. The strategy combines porting, modifying and adapting an overset library from the OpenFOAM fork platform (foam extend) to the standard OpenFOAM platform (ESI). Furthermore, in order to over come the well-known weakness of the standard OpenFOAM compressible solvers, the newly adapted overset library was integrated with an open source, density-based and coupled solver (HiSA: High Speed Aerodynamic), which uses the OpenFOAM technology. HiSA solver has been used after the necessary validation process for steady-state, transient and overset simulations. For steady-state validation, the DLR F6, the steady-state Eglin and the steady-state SDM results have been used. Whereas, for transient and overset validations, the pitching airfoil case has been used. These validation results are presented in this thesis. Additionally, a new force restrained model was developed to consider the externally applied forces on the store by the store ejectors. The results of the developed strategy have been compared with the wind tunnel tests of the Eglin case and with the solutions of two well-known com mercial codes, showing good agreements with them. While the study has focused on simulations with inviscid Euler equations (typical of the test case considered here), the viscosity effect on the solution has also been studied with Navier-Stokes equa tions and compared with other results in the literature, showing minor differences. Additionally, mesh and time step independence studies have been conducted using the same test case (Eglin). Furthermore, the Eglin test case at supersonic regime has been solved too using the developed strategy in this work. The obtained results were in good agreement with the experiment and other results in literature. To the best of our knowledge, this is the first work which studies and validates the store separation problem in transonic and supersonic regimes with OpenFOAM.