Browsing by Author "Atak, Kaan"

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Open Access
Comparison of iterative solvers in isogeometric boundary element formulation for heat transfer problems with non-linear boundary conditions
(Springer, 2024-09-10) Atak, Kaan; Gümüş, Özgür Can; Çetin, Barbaros
Boundary element method is a widely used numerical technique to solve partial differential equations (PDEs). Although the solution of linear PDEs with linear boundary conditions is straightforward, the presence of non-linearities requires additional steps which is the case for many heat transfer problems. In this study, a basis for heat transfer problems with non-linear boundary conditions is constructed by employing the isogeometric boundary element method, which leverages parametric functions used for geometry modeling to represent the field variables. The heat transfer problem with radiative and convective boundary conditions is solved with a non-linear solver in which different linear solvers are utilized. The performances of direct and iterative solvers are assessed. Preconditioners are employed to increase the convergence rate of iterative solvers. The accuracy of the proposed method is assessed by comparing the results with the analytical solution and the performance of each solver is determined by the elapsed time required for the convergence.
Restricted
Gülper İnanç üzerinden 1974-1996 yılları arasında: Türkiye'de kadın radyo ve televizyon spikeri olmak
(Bilkent University, 2020) Töngür, Deniz Vadi; Hazır, Ege Beren; Atak, Kaan; Erdoğan, Saray Edanur; Bodur, Zübeyir
1974-1996 yılları arasında Türkiye'de köklü siyasal ve toplumsal değişiklikler yaşanmıştır. Teknolojinin hızla gelişmesi, darbe sonrası baskıcı ortam gibi siyasi etkenler, Türkiye'nin sosyal yapısı ve dönemin medyası üzerinde etkilere neden olmuştur. Yapılan araştırmalardan yola çıkarak, 1974-1996 yılları arasında Türkiye'nin siyasi ve sosyal yapısı, Türk kadının iş ve toplum hayatındaki yeri, eğitim durumu ve medyası hakkında bir çalışma yürütülmüştür. Araştırma 1974 - 1996 yılları arasında TRT'de spikerlik yapmış olan Gülper İnanç ve onun hayatını kapsamaktadır. İnanç'ın aile yapısı, eğitimi ve bahsedilen dönemde Türkiye'de kadın haber ve televizyon spikeri olması ve 1974-1996 yıllarındaki TRT'nin işleyiş biçiminden bahsedilmiştir.
Embargo
Isogeometric boundary element formulation for cathodic protection of amphibious vehicles
(Elsevier Ltd., 2024-01) Gümüş, Özgür Can; Atak, Kaan; Çetin, Barış; Baranoğlu, Besim; Çetin, Barbaros
In this study, we propose an isogeometric boundary element formulation for the cathodic protection (CP) modeling for amphibious vehicles which includes the treatment of non-linear boundary conditions. Half-space Green’s functions are utilized which leads to the discretization of the hull surface only. Non-Uniform Rational B-splines (NURBS) are employed to represent both geometry and field variables to obtain higher accuracy where discontinuous collocation points are utilized to make multi-patch implementation easier. Variable condensation technique is applied to manipulate system matrices in a such way that the solution is iterated only on the surfaces where non-linear boundary conditions are assigned which results in reduced computational cost. The computational performance of the formulation is assessed with different solvers for a representative hull geometry.