Now showing items 1-20 of 22

  • A framework for water and carbon footprint analysis of national electricity production scenarios 

    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. ...

  • A Numerical Study of Shallow Mixing Development over Flat Surface and Dunes 

    Authors:Kirkil, Gökhan; Constantinescu, George
    Publisher and Date:(TSINGHUA UNIV, 2013)
    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 ...

  • A numerical study of the laminar necklace vortex system and its effect on the wake for a circular cylinder 

    Authors:Kirkil, Gökhan; Constantinescu, George
    Publisher and Date:(Amer Inst Physics, 2012)
    Large 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. ...

  • A Comparative Study of Energy Models for Turkish Electricity Market Using LEAP 

    Authors:Massaga, Daniel Julius; Kirkil, Gökhan; Çelebi, Emre
    Publisher and Date:(IEEE, 2019)
    Fossil fuel thermal power plants constitute a large part of the Turkish electricity generation capacity. Turkish government has been developing several energy policy documents to evaluate how various renewable energy sources of the country can be utilized optimally in the generation of electricity within the next 30 years. This study considers three scenarios in the transition to renewable energy for Turkey; the business as usual (BAU), energy conservation (EC) and renewable energy (REN) scenarios. ...

  • A Comparative Study of Energy Models for Turkish Electricity Market Using LEAP 

    Fossil fuel thermal power plants constitute a large part of the Turkish electricity generation capacity. Turkish government has been developing several energy policy documents to evaluate how various renewable energy sources of the country can be utilized optimally in the generation of electricity within the next 30 years. This study considers three scenarios in the transition to renewable energy for Turkey; the business as usual (BAU), energy conservation (EC) and renewable energy (REN) scenarios. ...

  • Detached eddy simulation of shallow mixing layer development between parallel streams 

    Authors:Kirkil, Gökhan
    Publisher and Date:(Elsevier Science Bv, 2015)
    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 medium size 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 ...

  • Development of a parallel 3D navier–stokes solver for sediment transport calculations in channels 

    Authors:Kirkil, Gökhan
    Publisher and Date:(MDPI AG, 2020)
    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 ...

  • Effects of cylinder Reynolds number on the turbulent horseshoe vortex system and near wake of a surface-mounted circular cylinder 

    Authors:Kirkil, Gökhan; Constantinescu, George
    Publisher and Date:(Amer Inst Physics, 2015)
    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 ...

  • Electricty demand and supply scenario analysis for nigeria using long range energy alternatives planning 

    Authors:İbrahim, Hanif Auwal
    Publisher and Date:(Kadir Has University, 2017)
    Electricity demand and supply forecasts are very important tools for determining solutions to the problems in the electricity sector such as power outages. The Long Range Energy Alternatives Planning (LEAP) energy model was used for this study because of its low data requirements. The forecast for electricity demand and supply for Nigeria was carried out from 2010-2040. Three scenarios were generated which include Business as Usual (BAU) Energy Conservation (EC) and Renewable Energy (REN). The ...

  • Energy transition scenario analysis for Turkey using long range energy alternatives planning (LEAP) 

    Authors:Massaga, Daniel Julius
    Publisher and Date:(Kadir Has University, 2019)
    Fossil fuel thermal power plants constitute a large part of the Turkish electricity generation capacity. The Turkish government has been developing several energy policy documents to evaluate how various renewable energy sources of the country can be utilized optimally in the generation of electricity for the next 30 years. The study considers three scenarios in the transition to renewable energy for Turkey; the business as usual (BAU), energy conservation (EE) and renewable energy (REN) scenarios ...

  • Flow and Turbulence Structure Around an In-Stream Rectangular Cylinder with Scour Hole 

    Authors:Kirkil, Gökhan; Constantinescu, George
    Publisher and Date:(TSINGHUA UNIV, 2013)
    An eddy resolving technique is used to reveal the unsteady dynamics of the coherent structures present in the flow field around an in-stream vertical cylinder with a scour hole at a channel Reynolds number of 240000. Such an investigation is important as most of the erosion around obstacles present in alluvial streams takes place after a scour hole of sufficiently large dimensions to stabilize the large-scale oscillations of the horseshoe vortex (HV) system has formed. The cylinder has a rectangular ...

  • Flow Structure in a Mixing Layer Developing Over Flat Bed at High Reynolds Numbers 

    Authors:Kirkil, Gökhan
    Publisher and Date:(CRC Press/Balkema, 2016)
    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 = 160000). 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 ...

  • Flow Structure in a Mixing Layer Developing Over Flat Bed at High Reynolds Numbers 

    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= 160000). 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. ...

  • Flow Structure in a Shallow Mixing Layer Developing over 2-D Dunes 

    Authors:Kirkil, Gökhan
    Publisher and Date:(EDP Sciences, 2018)
    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 over two-dimensional (2D) dunes. The study discusses the vertical non-uniformity in the mixing layer and provides a quantitative characterization of the growth of the large-scale quasi 2D coherent structures with the distance from the splitter plate. The presence of large-scale roughness elements in the form of an array of ...

  • Flow Structure in a Shallow Mixing Layer Developing over 2-D Dunes 

    Authors:Kirkil, Gökhan
    Publisher and Date:(E D P Sciences, 2018)
    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 over two-dimensional (2D) dunes. The study discusses the vertical non-uniformity in the mixing layer and provides a quantitative characterization of the growth of the large-scale quasi 2D coherent structures with the distance from the splitter plate. The presence of large-scale roughness elements in the form of an array of ...

  • Importance of LNG in Turkish natural gas supply security / LNG'nin Türkiye doğalgaz arz güvenliğindeki önemi 

    Authors:Alkan, Mehmet Batuhan
    Publisher and Date:(Kadir Has University, 2019)
    The Natural Gas has been increasing its share of usage day by day due to the technologic developments, low carbon emission, increasing natural gas reserve in the fossil-based energy market. Nowadays, the share of natural gas in the total energy mix is 24%. Hence, the natural gas has been seen as a transaction source because the countries are in the aim of zero carbon emission. LNG is the most increasing product in the natural gas market these days due to shale gas production areas are far away to ...

  • Large Eddy Simulation of Wind Flow over A Realistic Urban Area 

    Authors:Kirkil, Gökhan; Lin, Ching-Long
    Publisher and Date:(MDPI, 2020)
    A high-resolution large eddy simulation (LES) of wind flow over the Oklahoma City downtown area was performed to explain the effect of the building height on wind flow over the city. Wind flow over cities is vital for pedestrian and traffic comfort as well as urban heat effects. The average southerly wind speed of eight meters per second was used in the inflow section. It was found that heights and distribution of the buildings have the greatest impact on the wind flow patterns. The complexity of ...

  • Modeling of Wind Effects on Stratified Flows in Open Channels: A Model for the Istanbul Strait (Bosphorus) 

    Stratified flows in open channels arise as a result of density or surface level differences. If the channel is connected to a basin at one or both ends, strong winds originating from the basin cause the "wind setup" effect that increases the water level at the entrance of the channel. On the other hand, along the channel, persistent winds in the upper layer flow direction lead to an increase of the drift velocity and to a decrease in upper layer flow depth. The Istanbul Strait (Bosphorus) connecting ...

  • The renewable energy transition in Turkey 

    Authors:Yılmaz, Mesut Can
    Publisher and Date:(Kadir Has University, 2019)
    Energy is an integral part of human life. The energy demand has been increasing for many years. The primary energy source differed over time. Fossil fuels dominated the energy market since 19th century. Overuse of fossil fuels has created serious problems such as climate change. In order to tackle these problems renewable energy source (RES) utilization gained importance in the recent years. With the help of economic and technological improvements, the transition from fossil fuels to renewables ...

  • Resolved turbulence characteristics in large-eddy simulations nested within mesoscale simulations using the weather research and forecasting model 

    Authors:Mirocha, Jeff; Kosovic, Branko; Kirkil, Gökhan
    Publisher and Date:(2014)
    One-way concurrent nesting within the Weather Research and Forecasting Model (WRF) is examined for conducting large-eddy simulations (LES) nested within mesoscale simulations. Wind speed spectra and resolved turbulent stresses and turbulence kinetic energy from the nested LES are compared with data from nonnested simulations using periodic lateral boundary conditions. Six different subfilter-scale (SFS) stress models are evaluated using two different nesting strategies under geostrophically forced ...