Kirkil, Gökhan
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Name Variants
K.,Gokhan
G. Kirkil
Kirkil,Gokhan
Kirkil,G.
GÖKHAN KIRKIL
Kirkil, Gokhan
K., Gokhan
Kirkil, G.
Gökhan KIRKIL
Kirkil G.
Gökhan Kirkil
Gokhan, Kirkil
KIRKIL, Gökhan
K., Gökhan
KIRKIL, GÖKHAN
Kirkil, GÖKHAN
Kirkil, Gökhan
Kirkil, Gökhan
Kirkil, Gökhan
G. Kirkil
Kirkil,Gokhan
Kirkil,G.
GÖKHAN KIRKIL
Kirkil, Gokhan
K., Gokhan
Kirkil, G.
Gökhan KIRKIL
Kirkil G.
Gökhan Kirkil
Gokhan, Kirkil
KIRKIL, Gökhan
K., Gökhan
KIRKIL, GÖKHAN
Kirkil, GÖKHAN
Kirkil, Gökhan
Kirkil, Gökhan
Kirkil, Gökhan
Job Title
Doç. Dr.
Email Address
gokhan.kirkil@khas.edu.tr
Main Affiliation
Civil Engineering
Status
Website
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Scholarly Output
32
Articles
13
Citation Count
358
Supervised Theses
8
31 results
Scholarly Output Search Results
Now showing 1 - 10 of 31
Conference Object Citation - WoS: 0A Numerical Study of Shallow Mixing Development Over Flat Surface and Dunes(TSINGHUA UNIV, 2013) Kirkil, Gökhan; Kirkil, Gökhan; Constantinescu, GeorgeResults of a high resolution Detached Eddy Simulation (DES) are used to characterize the evolution of a shallow mixing layer developing between two parallel streams in a long open channel with a smooth flat bed and dunes. The study discusses the vertical non-uniformity in the mixing layer structure and provides a quantitative characterization of the growth of the large-scale quasi two-dimensional (2D) coherent structures with the distance from the splitter plate. Results show that in streamwise sections situated between 75D (D is the channel depth) and 150D from the splitter plate the width of the mixing layer close to the free surface is 20-30% more than the width in the near-bed region in the case in which the channel bed is flat. This is mostly because of the tilting of the mixing layer interface on the low-speed side toward the low speed stream as the free surface is approached. Power spectra of the horizontal velocity components show the presence of a -3 subrange at streamwise locations situated more than 10D from the splitter plate consistent with the presence of large-scale quasi 2D horizontal eddies and the transfer of energy (inverse energy cascade) from the smaller scales toward these eddies. Consistent with visualizations of the mass transport of a passive scalar within the mixing layer close to the free surface the estimated streamwise length of the quasi 2D mixing layer eddies is about 2.5 to 3.0 times larger than the local width of the mixing layer. The presence of large-scale roughness elements in the form of an array of two-dimensional dunes with a maximum height of 0.25D (D is the channel depth) induces a much more rapid and larger shift of the centerline of the mixing layer due to the increased influence of the bottom roughness.Master Thesis Decarbonization Potentials in the Turkish Energy Intensive Industries(Kadir Has Üniversitesi, 2021) Ünlü, Begüm; Kirkil, Gökhan; Kirkil, GökhanBiyoçeşitlilik ve iklim krizi ile mücadelede uluslararası kuruluşların önderliğinde küresel ısınmayı minimumda tutmak üzere bir dizi önlem alınmaktadır. Önlemlerden biri olan sera gazı emisyonlarının azaltılması için öncelikle enerji sektöründe yoğun karbonlu kaynaklardan düşük karbonlulara geçiş sağlanmaktadır. Lakin sadece enerji geçişinin emisyonları azaltmak için yeterli olmadığı bilinmektedir. Bu nedenle küresel emisyon salınımında enerjiden sonra ikinci sırada gelen sanayi sektöründe karbonsuzlaştırma yöntemlerine ağırlık verilmektedir. Çoğu gelişmiş ülkenin çalışmalarında Enerji Yoğun Endüstri olarak sınıflandırılan, üretim sürecinde yoğun enerji harcayan ve yoğun emisyona sebep olan alt sektörlere özel karbonsuzlaştırma önerileri kapsamlı bir şekilde ele alınmaktadır. Türkiye Sanayisi ise teknolojik araştırma ve geliştirmeleri enerji verimliliğine odaklanarak gerçekleştirmektedir. Karbonsuzlaştırma seçenekleri enerji verimliliğini de içine alan geniş bir yelpaze sunduğu için Türk Sanayisi tarafından da benimsenmelidir. Bu çalışma Türkiye'de üretim yapan enerji yoğun endüstrilerde karbonsuzlaştırma potansiyelini sunmayı amaçlamıştır. Çalışmada öncelikle karbonsuzlaştırma kavramı ve iklim krizi ile mücadalede ön saflarda yer alan uluslarası kuruluşların karbonsuzlaştırmaya bakış açısı incelenmiştir. Ardından küresel çapta uygulanan karbonsuzlaştırma seçenekleri araştırılıp enerji yoğun endüstrilere özel çözümler saptanmıştır. Daha sonra Türkiye'de enerji yoğun endüstriler alt sektör bazında incelenmiş ve uygun olan karbonsuzlaştırma önerileri sunulmuştur. Bu önerilerin hayata geçmesi için hükümetin, kuruluş ve sanayicilerin iklim krizi ile mücadelede küresel hedeflere uygun, ortak bir yaklaşım benimsemesi gerekmektedir. Ancak bu sayede sanayide karbonsuzlaştırma seçeneklerinin değerlendirilmesi mümkün olabilecektir.Conference Object Citation - Scopus: 1Genesys-Mod Turkey: Quantitative Scenarios for Low Carbon Futures of the Turkish Energy System(IEEE Computer Society, 2022) Hasturk, I.S.; Kirkil, Gökhan; Celebi, E.; Yucekaya, A.D.; Kirkil, G.This paper examines the quantitative scenarios for low-carbon futures of the Turkish energy system at aggregated (country level) and regionally disaggregated (NUTS-1 level) levels. We have employed four different storylines for the future European energy system. They are quantified and implemented for the European energy system (30 regions, mostly single countries, including Turkey) using the open-source global energy system model, GENeSYS-MOD v3.0. We have compared the results of all scenarios at aggregated and disaggregated levels and found that there are significant differences among them. Specifically, the hydrogen production (and its use) has increased considerably in the disaggregated model when compared to the aggregated level results. The major reason for these differences is found to be the better estimation of regional renewable capacity factors (wind and solar) in the disaggregated level compared to aggregated level. © 2022 IEEE.Article Citation - WoS: 30Citation - Scopus: 37Turkish Public Preferences for Energy(Elsevier Science, 2018) Ediger, Volkan S.; Kirkil, Gökhan; Kirkil, Gökhan; Ediger, Şevket Volkan; Çelebi, Emre; Ucal, Meltem; Ucal, Meltem Şengün; Kentmen-Cin, ÇiğdemPublic concern over energy supplies prices sustainability and efficiency has emerged as a major issue around the world. Yet most of what we know regarding public opinion on energy comes from North America and Europe. This paper presents the results from the 2016 Turkish Public Preferences for Energy Survey which included 1204 respondents and examined Turkish residents' household energy consumption energy policy preferences and environmental concerns. The main findings were that Turkish citizens consider natural gas and electricity highly expensive view dependence on imported energy as Turkey's most pressing energy challenge and recognize the problem of climate change. This lends public support for wind and solar power but at the same time energy issues and the environment policies of political parties do not affect voting choices and political preferences.Conference Object Citation - WoS: 0Flow Structure in a Mixing Layer Developing Over Flat Bed at High Reynolds Numbers(Iahr-int Assoc Hydro-environment Engineering Research, 2015) Kirkil, Gokhan; Kirkil, GökhanResults of a high resolution Detached Eddy Simulation (DES) are used to characterize the evolution of a shallow mixing layer developing between two parallel streams in a long open channel with a flat bed at a high Reynolds number (ReD= 160,000). The influence of Reynolds number on the development of the mixing layer as well as the vertical nonuniformity in the mixing layer structure is discussed. The numerical results show that as Reynolds number increases, the mixing layer development ceases earlier. Mixing layer growth rate and its change in the vertical direction at ReD= 160,000 are compared with experiments and a simulation at ReD= 16,000. Passive scalar is introduced at the tip of the splitter plate close to the free surface to estimate the size of the mixing structures based on mass transport. The effect of the Reynolds number on the shift of the centerline of the mixing layer is quantified.Article Citation - WoS: 0Citation - Scopus: 0The Role of Hydrogen in the Energy Mix: a Scenario Analysis for Turkey Using Osemosys(Mdpi, 2024) Kirkil, Gökhan; Kirkil, GokhanThe urgent need to tackle climate change drives the research on new technologies to help the transition of energy systems. Hydrogen is under significant consideration by many countries as a means to reach zero-carbon goals. Turkey has also started to develop hydrogen projects. In this study, the role of hydrogen in Turkey's energy system is assessed through energy modeling using the cost optimization analytical tool, Open Source Energy Modelling System (OSeMOSYS). The potential effects of hydrogen blending into the natural gas network in the Turkish energy system have been displayed by scenario development. The hydrogen is produced via electrolysis using renewable electricity. As a result, by using hydrogen, a significant reduction in carbon dioxide emissions was observed; however, the accumulated capital investment value increased. Furthermore, it was shown that hydrogen has the potential to reduce Turkey's energy import dependency by decreasing natural gas demand.Article Citation - WoS: 0Citation - Scopus: 0Development of a Parallel 3d Navier–stokes Solver for Sediment Transport Calculations in Channels(MDPI AG, 2020) Kirkil, Gökhan; Kirkil, GökhanWe propose a method to parallelize a 3D incompressible Navier–Stokes solver that uses a fully implicit fractional-step method to simulate sediment transport in prismatic channels. The governing equations are transformed into generalized curvilinear coordinates on a non-staggered grid. To develop a parallel version of the code that can run on various platforms, in particular on PC clusters, it was decided to parallelize the code using Message Passing Interface (MPI) which is one of the most flexible parallel programming libraries. Code parallelization is accomplished by “message passing” whereby the computer explicitly uses library calls to accomplish communication between the individual processors of the machine (e.g., PC cluster). As a part of the parallelization effort, besides the Navier–Stokes solver, the deformable bed module used in simulations with loose beds are also parallelized. The flow, sediment transport, and bathymetry at equilibrium conditions were computed with the parallel and serial versions of the code for the case of a 140-degree curved channel bend of rectangular section. The parallel simulation conducted on eight processors gives exactly the same results as the serial solver. The parallel version of the solver showed good scalability.Master Thesis Potential and Status of Renewable Energy Development in Energy Import-Dependent Countries Turkey and Pakistan(Kadir Has Üniversitesi, 2021) Majeed, Mohsina; Kirkil, Gökhan; Ediger, Şevket Volkan; Kirkil, GökhanHuman life cannot be imagined without the use of energy. Demand for energy, meanwhile, is increasing daily across the globe, while the uses and sources of energy have changed over time. Fossil fuels have dominated other energy sources since the 19th century but began causing problems such as climate change. In order to address these problems, renewable energy sources (RES) were accepted as an alternative energy sources in recent years and technical and economic developments make possible the energy transition from fossil fuels to renewables at an accelerated rate. Turkey and Pakistan are both developing countries with large populations and high levels of energy-import dependency, 77% and 80%, respectively. At the same time, Turkey and Pakistan both have enormous potential for RE such as solar, wind, hydro, biomass and geothermal, according to the validated RE-potential maps of these countries. Turkey and Pakistan are realizing renewable energy transition and seeking to shape their current energy structure in the favor of RES. The factors affecting RED in Turkey and Pakistan are enormous RE potential, supportive RE policies by government and energy security issues. There are some political, economic, technical and social problems for RED in Turkey and Pakistan that include lack of proper RE policies, extended and time-consuming governmental procedures, the lack of domestic production of goods, and other financing problems for RE projects. If proper policy support and efficient investment become available, RES can provide enough power to fulfill the country's energy demand and bring prosperity and sustainability to both countries. Current RED in these countries is not sufficient for complete energy transition from fossil fuels to renewables. However, RE potential in these countries is enough for complete energy transition. According to SWOT analysis Pakistan's RE sector has various investment opportunities for Turkish investors. It has a validated RE source mapping system and untapped highly potential solar and windy areas. Mini-hydro plants is also a successful RE business model in Pakistan. The government of Pakistan is also offering various incentives for RE investors. Keywords: Renewable energy transition, sustainability, solar, wind, fossil fuelArticle Citation - Scopus: 58Transition and Equilibration of Neutral Atmospheric Boundary Layer Flow in One-Way Nested Large-Eddy Simulations Using the Weather Research and Forecasting Model(2013) Mirocha, Jeffrey D.; Kirkil, Gökhan; Kirkil, Gökhan; Bou-Zeid, Elie; Chow, Fotini Katopodes; Kosovic, BrankoThe Weather Research and Forecasting Model permits finescale large-eddy simulations (LES) to be nested within coarser simulations an approach that can generatemore accurate turbulence statistics and improve other aspects of simulated flows.However errors are introduced into the finer domain fromthe nestingmethodology. Comparing nested domain flat-terrain simulations of the neutral atmospheric boundary layer with singledomain simulations using the same mesh but instead using periodic lateral boundary conditions reveals the errors contributed to the nested solution from the parent domain and nest interfaces. Comparison of velocity spectra shows good agreement among higher frequencies but greater power predicted on the nested domain at lower frequencies. Profiles of meanwind speed show significant near-surface deficits near the inflowboundaries but equilibrate to improved values with distance. Profiles of the vertical flux of x momentum show significant underprediction by the nested domain close to the surface and near the inlet boundaries. While these underpredictions of the stresses which cause the near-surface velocity deficits attenuate with distance within the nested domains significant errors remain throughout. Profiles of the resolved turbulence kinetic energy show considerable deviations from their single-domain values throughout the nested domains. The authors examine the accuracy of these parameters and their sensitivities to the turbulence subfilter stress model mesh resolution and grid aspect ratio and provide guidance to practitioners of nested LES. © 2013 American Meteorological Society.Article Citation - WoS: 44Citation - Scopus: 54A Numerical Study of the Laminar Necklace Vortex System and Its Effect on the Wake for a Circular Cylinder(Amer Inst Physics, 2012) Kirkil, Gökhan; Kirkil, Gökhan; Constantinescu, GeorgeLarge eddy simulation (LES) is used to investigate the structure of the laminar horseshoe vortex (HV) system and the dynamics of the necklace vortices as they fold around the base of a circular cylinder mounted on the flat bed of an open channel for Reynolds numbers defined with the cylinder diameter D smaller than 4460. The study concentrates on the analysis of the structure of the HV system in the periodic breakaway sub-regime which is characterized by the formation of three main necklace vortices. Over one oscillation cycle of the previously observed breakaway sub-regime the corner vortex and the primary vortex merge (amalgamate) and a developing vortex separates from the incoming laminar boundary layer (BL) to become the new primary vortex. Results show that while the classical breakaway sub-regime in which one amalgamation event occurs per oscillation cycle is present when the nondimensional displacement thickness of the incoming BL at the location of the cylinder is relatively large (delta*/D > 0.1) a new type of breakaway sub-regime is present for low values of delta*/D. This sub-regime which we call the double-breakaway sub-regime is characterized by the occurrence of two amalgamation events over one full oscillation cycle. LES results show that when the HV system is in one of the breakaway sub-regimes the interactions between the highly coherent necklace vortices and the eddies shed inside the separated shear layers (SSLs) are very strong. For the relatively shallow flow conditions considered in this study (H/D congruent to 1 H is the channel depth) at times the disturbances induced by the legs of the necklace vortices do not allow the SSLs on the two sides of the cylinder to interact in a way that allows the vorticity redistribution mechanism to lead to the formation of a new wake roller. As a result the shedding of large-scale rollers in the turbulent wake is suppressed for relatively large periods of time. Simulation results show that the wake structure changes randomly between time intervals when large-scale rollers are forming and are convected in the wake (von Karman regime) and time intervals when the rollers do not form. When the wake is in the von Karman regime the shedding frequency of the rollers is close to that observed for flow past infinitely long cylinders.
