Hasan Umur,  Akay

Akay, Hasan Umur

Profile URL

https://hdl.handle.net/20.500.14411/6751

Name Variants

Akay, Hasan
Hasan, Akay
Akay,Hasan
Hasan Akay
A.,Hasan
H., Akay
A., Hasan
Akay,H.
Akay H.
H.,Akay
Akay, Hasan U.
Akay, H. U.
Akay, Hasan U. U.

Job Title

Profesör Doktor

Email Address

hasan.akay@atilim.edu.tr

Main Affiliation

Automotive Engineering

Sustainable Development Goals

2

ZERO HUNGER

0

Research Products

11

SUSTAINABLE CITIES AND COMMUNITIES

0

Research Products

14

LIFE BELOW WATER

1

Research Products

6

CLEAN WATER AND SANITATION

0

Research Products

1

NO POVERTY

0

Research Products

5

GENDER EQUALITY

0

Research Products

9

INDUSTRY, INNOVATION AND INFRASTRUCTURE

0

Research Products

16

PEACE, JUSTICE AND STRONG INSTITUTIONS

0

Research Products

17

PARTNERSHIPS FOR THE GOALS

0

Research Products

15

LIFE ON LAND

0

Research Products

10

REDUCED INEQUALITIES

0

Research Products

7

AFFORDABLE AND CLEAN ENERGY

0

Research Products

8

DECENT WORK AND ECONOMIC GROWTH

0

Research Products

4

QUALITY EDUCATION

0

Research Products

12

RESPONSIBLE CONSUMPTION AND PRODUCTION

0

Research Products

3

GOOD HEALTH AND WELL-BEING

0

Research Products

13

CLIMATE ACTION

0

Research Products

Documents

131

Citations

1286

h-index

18

Go to Scopus profile

Documents

71

Citations

705

Go to WoS profile

Scholarly Output

15

Articles

9

Views / Downloads

82/278

Supervised MSc Theses

0

Supervised PhD Theses

1

WoS Citation Count

85

Scopus Citation Count

109

WoS h-index

4

Scopus h-index

5

Patents

0

Projects

0

WoS Citations per Publication

5.67

Scopus Citations per Publication

7.27

Open Access Source

3

Supervised Theses

1

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Journal	Count
8th International Conference on Education and New Learning Technologies (EDULEARN) -- JUL 04-06, 2016 -- Barcelona, SPAIN	2
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering	2
International Journal of Computational Fluid Dynamics	2
ARPN Journal of Engineering and Applied Sciences	1
Computers & Fluids	1

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Scholarly Output Search Results

Now showing 1 - 9 of 9

Citation - WoS: 7
Citation - Scopus: 7
A New Strategy for Solving Store Separation Problems Using Openfoam
(Sage Publications Ltd, 2022) Abuhanieh, Saleh; Akay, Hasan U.; Bicer, Baris
The ability of OpenFOAM to solve the problem of a store separating from an air vehicle (store separation problem) has been evaluated using a dynamic mesh (Overset/Chimera) technique for an industry-class (transonic and generic) benchmark test case. The major limitations of the standard libraries have been determined. To tackle these challenges, a new strategy has been proposed and implemented 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 overcome 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), which uses the OpenFOAM technology. Additionally, a force restrained model was developed to consider the externally applied forces on the store by the store ejectors. The accuracy of the developed strategy has been compared with wind tunnel tests and the solutions of two well-known commercial 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 equations and compared with other results in the literature, showing minor differences. To the best of the authors' knowledge, this is the first work which studies and validates the store separation problem in transonic regime with OpenFOAM.
A Phenomenological Study of Instructors’ Experiences on an Open Source Learning Management System
(Procedia - Social and Behavioral Sciences, 2011) Çiğdemoğlu, Ceyhan; Arslan, Harika Özge; Akay, Hasan
This 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.
Citation - Scopus: 1
Improved Parallel Preconditioners for Multidisciplinary Topology Optimisations
(Taylor & Francis Ltd, 2016) Akay, H. U.; Oktay, E.; Manguoglu, M.; Sivas, A. A.
Two commonly used preconditioners were evaluated for parallel solution of linear systems of equations with high condition numbers. The test cases were derived from topology optimisation applications in multiple disciplines, where the material distribution finite element methods were used. Because in this optimisation method, the equations rapidly become ill-conditioned due to disappearance of large number of elements from the design space as the optimisations progresses, it is shown that the choice for a suitable preconditioner becomes very crucial. In an earlier work the conjugate gradient (CG) method with a Block-Jacobi preconditioner was used, in which the number of CG iterations increased rapidly with the increasing number processors. Consequently, the parallel scalability of the method deteriorated fast due to the increasing loss of interprocessor information among the increased number of processors. By replacing the Block-Jacobi preconditioner with a sparse approximate inverse preconditioner, it is shown that the number of iterations to converge became independent of the number of processors. Therefore, the parallel scalability is improved.
A Gradient Enhanced Efficient Global Optimization-Driven Aerodynamic Shape Optimization Framework
(MDPI, 2025) Senol, Niyazi; Akay, Hasan U.; Yigit, Sahin
The aerodynamic optimization of airfoil shapes remains a critical research area for enhancing aircraft performance under various flight conditions. In this study, the RAE 2822 airfoil was selected as a benchmark case to investigate and compare the effectiveness of surrogate-based methods under an Efficient Global Optimization (EGO) framework and an adjoint-based approach in both single-point and multi-point optimization settings. Prior to optimization, the computational fluid dynamics (CFD) model was validated against experimental data to ensure accuracy. For the surrogate-based methods, Kriging (KRG), Kriging with Partial Least Squares (KPLS), Gradient-Enhanced Kriging (GEK), and Gradient-Enhanced Kriging with Partial Least Squares (GEKPLS) were employed. In the single-point optimization, the GEK method achieved the highest drag reduction, outperforming other approaches, while in the multi-point case, GEKPLS provided the best overall improvement. Detailed comparisons were made against existing literature results, with the proposed methods showing competitive and superior performance, particularly in viscous, transonic conditions. The results underline the importance of incorporating gradient information into surrogate models for achieving high-fidelity aerodynamic optimizations. The study demonstrates that surrogate-based methods, especially those enriched with gradient information, can effectively match or exceed the performance of gradient-based adjoint methods within reasonable computational costs.
Citation - Scopus: 1
Prediction of Ice Accretion Shapes on Aircraft Wings Using Open-Source Software
(Asian Research Publishing Network, 2021) Edeeb,S.; Akay,H.U.; Ozgen,S.
Ice accretion on aircraft components starts when an aircraft flies through atmospheric clouds containing supercooled liquid droplets, which have a temperature below freezing point but are still in a liquid state. Ice accretion occurs when water droplets impinge and freeze on the unprotected frontal regions of aircraft surfaces. The accumulated ice on aircraft components degrades the aircraft performance and causes serious flight problems. In this study, a computational fluid dynamics package is developed using open-source software. The created package is used to predict rime and glaze ice shapes on a wing airfoil for different icing condition cases. The results show a satisfactory agreement in ice shape prediction obtained using the OpenFOAM and Octave software with the corresponding data in the literature © 2006-2021 Asian Research Publishing Network (ARPN). All rights reserved.
Citation - WoS: 4
Citation - Scopus: 5
Numerical Investigation of Store Separation From Cavity Problems at High Speeds
(Sage Publications Ltd, 2023) Abuhanieh, Saleh; Akay, Hasan U.
In this work, the ability of open-source CFD tools to conduct store separation simulations from cavities is evaluated and validated using a generic test case from the literature. Firstly, the ability and accuracy of these tools for solving cavity flows at high speeds are evaluated. Secondly, their competence in predicting the trajectory of a generic store from a generic deep cavity is checked. Finally, and in order to reduce the associated computational costs, a release-time dependability factor from the recent literature is studied and evaluated. The obtained results using the selected open-source CFD tools matched quite well with the wind tunnel results. Furthermore, the results show that predicting the release-time dependability using a quantified index/factor can be a potential remedy for reducing the computational cost for this type of CFD simulations.
Improved Simulation of Cryogenic Fluid Mixing at Supercritical Pressures
(Public Library Science, 2023) Omair, Muhammad; Akay, Hasan U. U.
The combustion chamber pressure of rockets, gas turbines and diesel engines is known to be above the critical pressure of fuel and oxidizers. In the case of rocket engines the fuel and/or oxidizer is often injected at cryogenic temperatures. This elevated combustion chamber pressure and low temperature demands special treatment for numerical analysis of mixing. Thus a novel implementation of an improved equation of state has been proposed which provides better estimation of densities. Experimental and numerical data from literature has been used for validation of the analysis methodology.
Citation - WoS: 6
Flows Around Moving Bodies Using a Dynamic Unstructured Overset-Grid Method
(Taylor & Francis Ltd, 2010) Liu, Jingxin; Akay, Hasan U.; Ecer, Akin; Payli, Resat U.
In this article, a computational fluid dynamics algorithm is presented for simulations of complex unsteady flows around rigid moving bodies using an unstructured overset-grid method. For this purpose, a highly automated, three-dimensional, tetrahedral, unstructured overset-grid method is developed with one-cell-width overlapping zone in order to model the arbitrary geometries for steady and unsteady flow simulations. A method has been described to obtain the inter-grid boundaries of the one-cell-wide overlapping zone shared by a background grid and a minor grid. In the overset-grid methodology, vector intersection algorithm and bounding box techniques have been utilised. The mesh refinement and overset-scheme conservation studies proved the accuracy and efficiency of the method developed here. The applications of the developed algorithms were also performed through simulations that included complex internal flows around a flow-control butterfly valve as well as flows in an internal combustion engine with a moving piston. Lastly, validations with experimental data were conducted for both steady and unsteady flows around rigid bodies with relative motions.
Citation - WoS: 18
Citation - Scopus: 25
Three-Dimensional Structural Topology Optimization of Aerial Vehicles Under Aerodynamic Loads
(Pergamon-elsevier Science Ltd, 2014) Oktay, Erdal; Akay, Hasan Umur; Akay, Hasan U.; Sehitoglu, Onur T.; Akay, Hasan Umur; Automotive Engineering; Automotive Engineering
A previously developed density distribution-based structural topology optimization algorithm coupled with a Computational Fluid Dynamics (CFD) solver for aerodynamic force predictions is extended to solve large-scale problems to reveal inner structural details of a wing wholly rather than some specific regions. Resorting to an iterative conjugate gradient algorithm for the solution of the structural equilibrium equations needed at each step of the topology optimizations allowed the solution of larger size problems, which could not be handled previously with a direct equation solver. Both the topology optimization and CFD codes are parallelized to obtain faster solutions. Because of the complexity of the computed aerodynamic loads, a case study involving optimization of the inner structure of the wing of an unmanned aerial vehicle (UAV) led to topologies, which could not be obtained by intuition alone. Post-processing features specifically tailored for visualizing computed topologies proved to be good design tools in the hands of designers for identifying complex structural components. (C) 2013 Elsevier Ltd. All rights reserved.

Akay, Hasan Umur

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Sustainable Development Goals

2

ZERO HUNGER

0

Research Products

11

SUSTAINABLE CITIES AND COMMUNITIES

0

Research Products

14

LIFE BELOW WATER

1

Research Products

6

CLEAN WATER AND SANITATION

0

Research Products

1

NO POVERTY

0

Research Products

5

GENDER EQUALITY

0

Research Products

9

INDUSTRY, INNOVATION AND INFRASTRUCTURE

0

Research Products

16

PEACE, JUSTICE AND STRONG INSTITUTIONS

0

Research Products

17

PARTNERSHIPS FOR THE GOALS

0

Research Products

15

LIFE ON LAND

0

Research Products

10

REDUCED INEQUALITIES

0

Research Products

7

AFFORDABLE AND CLEAN ENERGY

0

Research Products

8

DECENT WORK AND ECONOMIC GROWTH

0

Research Products

4

QUALITY EDUCATION

0

Research Products

12

RESPONSIBLE CONSUMPTION AND PRODUCTION

0

Research Products

3

GOOD HEALTH AND WELL-BEING

0

Research Products

13

CLIMATE ACTION