Gökhan Kirkil

Kirkil, Gökhan

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

Job Title

Doç. Dr.

Email Address

gokhan.kirkil@khas.edu.tr

ORCID ID

0000-0001-9213-007X

Scopus Author ID

12039334900

Full item page

Scholarly Output

31

Articles

12

Citation Count

358

Supervised Theses

8 Scholarly Output Search Results

Now showing 1 - 10 of 30

Potential and status of renewable energy development in energy import-dependent countries Turkey and Pakistan
(Kadir Has Üniversitesi, 2021) Kirkil, Gökhan; Ediger, Şevket Volkan; Kirkil, Gökhan
Human 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 fuel
Citation Count: 0
Development of a parallel 3D navier–stokes solver for sediment transport calculations in channels
(MDPI AG, 2020) Kirkil, Gökhan
We 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.
Citation Count: 29
Turkish public preferences for energy
(Elsevier Science, 2018) Kirkil, Gökhan; Ediger, Şevket Volkan; Ucal, Meltem; Ucal, Meltem Şengün; Kentmen-Cin, Çiğdem
Public 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.
Citation Count: 0
A Numerical Study of Shallow Mixing Development over Flat Surface and Dunes
(TSINGHUA UNIV, 2013) Kirkil, Gökhan; Constantinescu, George
Results 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.
Decarbonization potentials in the Turkish energy intensive industries
(Kadir Has Üniversitesi, 2021) Kirkil, Gökhan; Kirkil, Gökhan
Biyoçeşitlilik 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.
Citation Count: 0
Flow structure in a mixing layer developing over flat bed at high Reynolds numbers
(Crc Press-balkema, 2016) Kirkil, Gökhan
Results 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 (Re-D = 160,000). The influence of Reynolds number on the development of the mixing layer as well as the vertical non-uniformity in the mixing layer structure is discussed. The numerical results show that as Reynolds number increases, the mixing layer grows rapidly but also stabilizes more quickly. The shift of the centerline of the mixing layer is toward the low-speed side is less for high Reynolds number simulation than low Reynolds number simulation. Mixing layer growth rate and its change in the vertical direction are compared with experiments and a simulation at Re-D = 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.
Citation Count: 0
FLOW STRUCTURE IN A MIXING LAYER DEVELOPING OVER FLAT BED AT HIGH REYNOLDS NUMBERS
(Iahr-int Assoc Hydro-environment Engineering Research, 2015) Kirkil, Gökhan
Results 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.
Citation Count: 0
GENeSYS-MOD Turkey: Quantitative Scenarios for Low Carbon Futures of the Turkish Energy System
(IEEE Computer Society, 2022) 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.
Citation Count: 80
Effects of cylinder Reynolds number on the turbulent horseshoe vortex system and near wake of a surface-mounted circular cylinder
(Amer Inst Physics, 2015) Kirkil, Gökhan; Constantinescu, George
The turbulent horseshoe vortex (HV) system and the near-wake flow past a circular cylinder mounted on a flat bed in an open channel are investigated based on the results of eddy-resolving simulations and supporting flow visualizations. Of particular interest are the changes in the mean flow and turbulence statistics within the HV region as the necklace vortices wrap around the cylinder's base and the variation of the mean flow and turbulence statistics in the near wake in between the channel bed and the free surface. While it is well known that the drag crisis induces important changes in the flow past infinitely long circular cylinders the changes are less understood and more complex for the case of flow past a surface-mounted cylinder. This is because even at very high cylinder Reynolds numbers Re-D the flow regime remains subcritical in the vicinity of the bed surface due to the reduction of the incoming flow velocity within the bottom boundary layer. The paper provides a detailed discussion of the changes in the flow physics between cylinder Reynolds numbers at which the flow in the upstream part of the separated shear layers (SSLs) is laminar (Re-D = 16 000 subcritical flow regime) and Reynolds numbers at which the transition occurs inside the attached boundary layers away from the bed and the flow within the SSLs is turbulent (Re-D = 5 * 10(5) supercritical flow regime). The changes between the two regimes in the dynamics and level of coherence of the large-scale coherent structures (necklace vortices vortex tubes shed in the SSLs and roller vortices shed in the wake) and their capacity to induce high-magnitude bed friction velocities in the mean and instantaneous flow fields and to amplify the near-bed turbulence are analyzed. Being able to quantitatively and qualitatively describe these changes is critical to understand Reynolds-number-induced scale effects on sediment erosion mechanisms around cylinders mounted on a loose bed which is a problem of great practical relevance (e.g. for pier scour studies). (C) 2015 AIP Publishing LLC.
Citation Count: 42
A framework for water and carbon footprint analysis of national electricity production scenarios
(Pergamon-Elsevier Science Ltd, 2017) Kirkil, Gökhan; Küçükvar, Murat; Onat, Nuri Cihat; Kirkil, Gökhan
While carbon footprint reduction potential and energy security aspects of renewable and non-renewable resources are widely considered in energy policy their effects on water resources are mostly overlooked. This research aims to develop a framework for water and carbon footprint analysis to estimate the current and future trends of water consumption and withdrawal by electricity production sectors for national energy development plans - alongside carbon emissions from various electricity sources. With this motivation the Turkish electric power industry is selected as a case study and a decision support tool is developed to determine the water consumption withdrawal and carbon emissions from energy mixes under three different scenarios namely Business-As-Usual (BAU) Official Governmental Plan (OGP) and Renewable Energy-Focused Development Plan (REFDP). The results indicate that water is used substantially even by renewable resources such as hydroelectricity and biomass which are generally considered to be more environmental friendly than other energy sources. The average water consumption of the OGP energy mix in 2030 is estimated to be about 8.1% and 9.6% less than that of the BAU and REFDP scenarios respectively. On the other hand it is found that the water withdrawal of the energy mix in 2030 under the REFDP scenario is about 46.3% and 16.9% less than that of BAU and OGP scenarios. Carbon emissions from BAU are projected to be 24% higher than OGP and 39% higher than REFDP in 2030. Carbon emissions and water usage are strongly correlated in BAU scenario as compared with OGP and REFDP thus carbon friendly energy sources will result in fewer water consumptions and withdrawals particularly under REFDP. (C) 2017 Elsevier Ltd. All rights reserved.