Levent Yilmaz | Istanbul Technical University (original) (raw)

Papers by Levent Yilmaz

EGUGA, Apr 1, 2009

An analytical model is developed for free-surface flow over an erodible bed and is used to invest... more An analytical model is developed for free-surface flow over an erodible bed and is used to investigate the stability of the fluid-bed interface and the characteristics of the bed features by measuring the shear stress distribution with hot-film sensors. The model is based on the potential flow over a two-dimensional, moving, wavy bed with a sinusoidal profile of varying amplitude, and a sediment transport relation in which the transported rate is proportional to the power of the fluid velocity at the level of the meandering bed. The conflicting definition of the braided pattern raise the issues concerning (a) the difference between mid-channel bars and islands, (b) the precise nature of the interaction between flow stage and bars or islands and (c) the differences between the mechanisms of channel divergence that lead to river patterns termed as "braided" and those defined as "anastomosing". Consideration is given to the factors involved in determining the shear stress distribution at the flow boundary layer. The experimental results are presented in two parts. Experimental observations of meander evolution described qualitatively. The most important parameter is the shear stress distribution, because of the inhomogeneous distribution of boundary layer meander features. At the wavy boundary layer, the shear stress distribution, measured with WTG-50 hotfilm-anemometer is given graphically and theoretically.

Determining the hydroelectric power potential of ungauged or poorly gauged basins gains importanc... more Determining the hydroelectric power potential of ungauged or poorly gauged basins gains importance parallel with the increasing electricity consumption. This study presents some simple methods to predict flow to determine the hydroelectric power potential of poorly gauged basins, such as the precipitation–elevation, average precipitation, and average basin elevation methods. Results of these methods are compared with the available flow measurements. The poorly gauged Solaklı Basin, which is located in Trabzon, in the Eastern Black Sea Region of Turkey, is selected as the pilot area. The hydroelectric power potential of the planned small hydroelectric power plants in this area is estimated using different flow prediction methods.

WIT Transactions on the Built Environment, 1970

The maritime structures are subjected to the effects of nonbreaking, breaking and broken waves. Q... more The maritime structures are subjected to the effects of nonbreaking, breaking and broken waves. Quaywalls are designed by the hydrostatic pressures and dynamical forces of the wave motions; and Morison's forces to the legs are also taken into account if their combinations cause greater stresses. Members and fasteners of the quaywalls in harbour which are subjected to repeated variations and reversals of stresses shall be designed so that the maximum stress does not exceed the given allowable stresses, and the actual range of stress does not exceed the allowable fatigue stress range. The main objective of the paper is to present a procedure to calculate effective stress range for quaywall members under variable-amplitude randomsequence stress spectrums and to give analytical method for predicting fatigue life under variable amplitude stress spectrums from constant amplitude fatigue stress.

Su, dunyada insan hayatinin devami icin en onemli yasam gerekliliklerinin basinda gelen ancak oze... more Su, dunyada insan hayatinin devami icin en onemli yasam gerekliliklerinin basinda gelen ancak ozellikle son yillarda kuresel iklim degisikliginin etkisiyle tehlikeli bir bicimde azalmaya baslayan bir kaynaktir. Kuskusuz, suyu onemli kilan bir diger unsur da suyun ekonomik bir meta haline gelmesi, agir sanayi ve enerji uretiminde kullanilan temiz bir kaynak olmasidir. Dunyanin artan nufusu, uretim imkânlarinin artmasi gibi pek cok etken suya olan ihtiyaci surekli artirirken, kuresel iklim degisikligi ve cevreye verilen zarar ile birlikte su kaynaklari azaltmaya baslamis, bu durum da suyu her zamankinden daha onemli bir hale getirmistir. Calismada suyun onemine iliskin bilgilere yer verilmis, konu ile ilgili literatur incelenmis, ardindan da Turkiye acisindan Ortadogu bolgesindeki olasi riskler ele alinmistir.

Journal of Imaging Science and Technology, 2015

Simulation and modeling of turbulent flow, and of turbulent reacting flow in particular, involve ... more Simulation and modeling of turbulent flow, and of turbulent reacting flow in particular, involve solving for and analyzing time-dependent and spatially dense tensor quantities, such as turbulent stress tensors. The interactive visual exploration of these tensor quantities can effectively steer the computational modeling of combustion systems. In this article, the authors analyze the challenges in dense symmetric-tensor visualization as applied to turbulent combustion calculation; most notable among these challenges are the dataset size and density. They analyze, together with domain experts, the feasibility of using several established tensor visualization techniques in this application domain. They further examine and propose visual descriptors for volume rendering of the data. Of these novel descriptors, one is a density-gradient descriptor which results in Schlieren-style images, and another one is a classification descriptor inspired by machine-learning techniques. The result is a hybrid visual analysis tool to be utilized in the debugging, benchmarking and verification of models and solutions in turbulent combustion. The authors demonstrate this analysis tool on two example configurations, report feedback from combustion researchers, and summarize the design lessons learned.

Celal Bayar Üniversitesi Sosyal Bilimler Dergisi, 2014

hkmo.org.tr

Hidroloji ve su kaynakları çalışmalarında son yıllarda Uzaktan Algılama (UA) yöntemleri ile sağla... more Hidroloji ve su kaynakları çalışmalarında son yıllarda Uzaktan Algılama (UA) yöntemleri ile sağlanan uydu görüntüleri ve Coğrafi Bilgi Sistemleri (CBS) kullanılmaktadır. Uydu verileri ile yersel ölçümlere göre hızlı ve ekonomik çözümler elde edilebilmektedir. Bu çalışmada Solaklı Havzası için arazi kullanımının belirlenmesi amacıyla IRS P6, Sayısal Yükseklik Modeli (SYM)'nin oluşturulması amacı ile de stereo IRS P5 uydu verisi kullanılmıştır. SYM kullanılarak havzanın akış yönü ve yüzey akış haritaları oluşturulmuştur. Sonraki aşamada SYM, CBS yazılımda analiz edilerek havzanın sentetik drenaj ağı oluşturulmuştur. Bu drenaj ağı üzerinde, kolların kesişim noktaları üzerinde belirlenen istasyon noktalarını besleyen alt havzalar, CBS ortamında belirlenmiştir. Son aşamada alt havzalara ait topografik parametreler hesaplanmıştır. Havzada ve komşu havzalardaki meteoroloji istasyonlarının yağış verileri kriging yöntemi ile değerlendirilip havzaya ait eşyağış haritası oluşturulmuştur. Topografik parametreler ve eşyağış eğrilerinden elde edilen ortalama alansal yağış bilgileri çoklu regresyonla elde edilen akım denkleminde kullanılarak istasyon noktalarına ait akım değerleri hesaplanmıştır.

Sediment Transport, 2011

have limited widths and lengths. The flow and the hydraulic properties of the meandering river, t... more have limited widths and lengths. The flow and the hydraulic properties of the meandering river, the amount of sand moving along the bed, and the rate of bank erosion determine these limits. When a bend reaches this width, a chute forms and a new bend develops farther downstream. Distorted bends and natural cutoffs are caused by local changes in the character of bank materials. Several hypotheses have been brought forward to explain meandering. Meandering has been attributed to the earth's rotation; to the excessive slope and energy of a river (

Experiences: Aug. 1968 Apr. 1969 Engineer at State Water Supply Department, Trabzon. Apr. 1969 Se... more Experiences: Aug. 1968 Apr. 1969 Engineer at State Water Supply Department, Trabzon. Apr. 1969 Sept. 1970 Military Service, Ankara. Oct. 1970 July 1978 Graduate student and research fellow, İstanbul. July 1978 July 1979 Post-doctoral fellow at Colorado State Univ., USA. July 1979 July 1980 Post-doctoral fellow at Mississippi State Univ., USA. July 1980 Apr. 1982 Assistant Professor at Tech. Univ. of Istanbul. Apr. 1982 Nov. 1988 Associate Professor at Tech. Univ. of Istanbul. Nov. 1988 Jan. 1993 Professor at Technical Univ. of Istanbul. Jan. 1993 Sept. 1993 Dean of Engineering Faculty at Sakarya Univ. Sakarya. Sept. 1993 Feb. 1995 Professor at Tech. Univ. of Istanbul, İstanbul. Feb. 1995 Feb. 1996 Professor, Eastern Mediterranean Univ., Cyprus. Feb. 1996 – May 2003 Professor at Technical University of Istanbul; Istanbul. May 2003 – Oct. 2009 Head of Hydraulic Div. at Tech. Univ. of Istanbul; İstanbul. Mar. 2009 – Apr. 2014 Member of Board of Management at İSKİ, İstanbul Jan. 2015 – ...

This article provides an overview of the Sapanca Lake water capacity management program,including... more This article provides an overview of the Sapanca Lake water capacity management program,including a description of the hydrologic conditions in the region, an overview of the lake storage system, and its water use control capabilities, and a description of forecasting procedures and water-use control operating strategy. The development and implementation of water capacity management program, and its role in reducing water amount at the Sapanca valley are also presented. The article closes with a discussion of the role of water management advances on future operations. As a conclusion, withdrawn water differs with the months. Because Sapanca Lake interact with ground water in three basic ways: some receive ground water inflow throughout their entire bed, some have seepage loss to ground water throughout their entire bed, but Sapanca Lake receive ground water inflow through part of their bed from Sakarya River, which is situated 5 km away from the eastern part of the Sapanca District ...

Closed - form mathematical models are developed for the rate of development of secondary current,... more Closed - form mathematical models are developed for the rate of development of secondary current, and for bed topography in meandering, erodible-bed streams of arbitrary plan form. The formulations utilise conservation of flux-of-moment-of - momentum as the additional relation required to complete the formulation for the radial water-surface slope and radial bed- shear stress. The flow distribution is computed utilising the secondary-flow and bed topography. In this way, the secondary-flow velocity calculation is uncoupled from the calculation of the radial mass-shift velocity and streamwise velocity distributions, which were obtained from the depth-integrated equations expressing conservation of mass and streamwise momentum. The numerical model developed was tested using the hydraulic and sediment-transport characteristics of flume experiments. Generally good agreement was obtained between measured and computed distributions of flow depth and depth-averaged oscillatory shear stress...

Lateral vibration of underwater suspended pipeline was investigated for the case of pipeline osci... more Lateral vibration of underwater suspended pipeline was investigated for the case of pipeline oscillation due to vortex shedding. Firstly, tension force was defined at the connection legs on sea bottom. To define the dynamical equation the analogy of the Mathieu equation was applied, meanwhile Ince-Strutt diagram was used for its solution. As a numerical example we used the behavior of pipeline in a project between Turkey and North Cyprus in the East Mediterranean Sea. Good agreement was found between the theoretical results and experimental data of Danish Hydraulic Institute (DHI

Journal of Geographical Research, Mar 14, 2019

In this research it is established a classification system by which to characterize atmospheric c... more In this research it is established a classification system by which to characterize atmospheric conditions, specifically those related to winter extra tropical storms and fair weather. Numerous classification schemes have been proposed to categorize atmospheric conditions in a variety of environments-however, since meteorological processes are inherently complicated, these are of necessity based on criteria that suit a particular purpose. The system employed in this project was ultimately designed to differentiate between: 1. fair weather and storm conditions; 2. different phases of extratropical storms; 3. extratropical storms of different intensities and synoptic types.

Public Sector Crisis Management, 2020

Monte Carlo in Monaco is given to the theory for mathematics, whose simulation process involves g... more Monte Carlo in Monaco is given to the theory for mathematics, whose simulation process involves generating chance variables and exhibiting random behaviours in nature. This simulation is a powerful statistical analysis tool and widely used in both non-engineering fields and engineering fields for new perspectives. This simulation has been applied to diverse problems ranging from the simulation of complex physical phenomena such as atom collisions, to the simulation of river boundary layers as meanders and Dow Jones forecasting. It can deal with many random variables, various distribution types and highly nonlinear engineering models, while Monte Carlo is also suitable for solving complex engineering problems in two areas which are varying randomly. Monte Carlo simulation is given as an application for hydrogen energy potential determination.

Journal of Geographical Research, 2019

Bank full discharge is generally considered to be the dominant steady flow which would generate t... more Bank full discharge is generally considered to be the dominant steady flow which would generate the same regime channel shape and dimensions as the natural sequences of flows would. This is because investigation on the magnitude and frequency of sediment transport have determined that for stable rivers the flow which in the longer term transports most material has the same frequency of occurrence as bankfull flow. For stable gravel-bed rivers, this is considered to be the 1.5-year flood.

CLEAN - Soil, Air, Water, 2009

DESALINATION AND WATER TREATMENT

The efficacy of nanofiltration (NF) in removing sulfate from a high sulfate content (370-460 mg/L... more The efficacy of nanofiltration (NF) in removing sulfate from a high sulfate content (370-460 mg/L) surface water was investigated. NF tests were carried out using a laboratory-scale cross-flow NF module operated in total-recycle (full-recycle) mode. Membranes of varying characteristics; namely, DK-NF (Desal DK: GE Osmonics, USA), DL-NF (Desal DL: GE Osmonics, USA), and NF270 (Dow Filmtec Co., USA) were tested, and the effects of main operational parameters of cross-flow velocity, trans-membrane pressure, and pretreatment on permeate flux and sulfate removal were evaluated. The NF270 membrane exhibited the highest permeate flux and was found to be the best of the three membranes tested, with over 98% sulfate removal. The DK-NF membrane, which was poor in performance with a high flux decline, provided the lowest sulfate removal, lowest permeate flux, and highest fouling. Microfiltration (2.5-µm), as pretreatment, provided no considerable improvement in permeate flux. When the effects of operational parameters on NF performance using the DL-NF membrane were sought, it appeared that permeate flux, and sulfate removal efficiency did not change at all with trans-membrane pressure and cross-flow velocity. The study is expected to provide useful information about the NF of drinking water with high sulfate content in the future.

Simulation Foundations, Methods and Applications

The use of computational simulation in science is now pervasive. However, while model development... more The use of computational simulation in science is now pervasive. However, while model development environments have advanced to a degree that allows scientists to build sophisticated models, there are still impediments that limit their utility within the broader context of the scientific method. Despite availability of effective tools that assist scientists in routine aspects of scientific workflow management and analytics, other steps, including explanation, evidential reasoning, and decision-making, continue to limit the process of causal reasoning in knowledge discovery and evaluation. This chapter examines the types, functions, and purposes of models in relation to the scientific method, identifies the issues and challenges pertaining to information abstraction and cognitive support for computational discovery, and delineates a model-driven cognitive systems approach for simulation-based science.

The development of the dunes are governed by the effects of turbulence. Turbulence is a type of f... more The development of the dunes are governed by the effects of turbulence. Turbulence is a type of fluid flow that is strongly rotational and apparently chaotic. Turbulence separates nearby parcels of air and thus mixed fluid properties . The evolution of sand dunes is determined by the interactions between the atmosphere, the surface and the transport and deposition of sand. We are concerned with this physical process and its computational simulation from three perspectives; namely, (1) flow structure; (2) sand transport and deposition and (3) interactions between flow structure and sand transport-deposition, which determine the dune morphology.

Motivation and problem-domain preferences of scientists can affect aggregate level emergence and ... more Motivation and problem-domain preferences of scientists can affect aggregate level emergence and growth of problem domains in science. In this study, we introduce an agent-based model that is based on information foraging and expectancy theory to examine the impact of rationality and openness on the growth and evolution of scientific domains. We simulate a virtual socio-technical system, in which scientists with different preferences search for problem domains to contribute knowledge, while considering their motivational gains. Problem domains become mature and knowledge spills occur over time to facilitate creation of new problem domains. We conduct experiments to examine emergence and growth of clusters of domains based on local interactions and preferences of scientists and present preliminary qualitative observations.

EGUGA, Apr 1, 2009

An analytical model is developed for free-surface flow over an erodible bed and is used to invest... more An analytical model is developed for free-surface flow over an erodible bed and is used to investigate the stability of the fluid-bed interface and the characteristics of the bed features by measuring the shear stress distribution with hot-film sensors. The model is based on the potential flow over a two-dimensional, moving, wavy bed with a sinusoidal profile of varying amplitude, and a sediment transport relation in which the transported rate is proportional to the power of the fluid velocity at the level of the meandering bed. The conflicting definition of the braided pattern raise the issues concerning (a) the difference between mid-channel bars and islands, (b) the precise nature of the interaction between flow stage and bars or islands and (c) the differences between the mechanisms of channel divergence that lead to river patterns termed as "braided" and those defined as "anastomosing". Consideration is given to the factors involved in determining the shear stress distribution at the flow boundary layer. The experimental results are presented in two parts. Experimental observations of meander evolution described qualitatively. The most important parameter is the shear stress distribution, because of the inhomogeneous distribution of boundary layer meander features. At the wavy boundary layer, the shear stress distribution, measured with WTG-50 hotfilm-anemometer is given graphically and theoretically.

Determining the hydroelectric power potential of ungauged or poorly gauged basins gains importanc... more Determining the hydroelectric power potential of ungauged or poorly gauged basins gains importance parallel with the increasing electricity consumption. This study presents some simple methods to predict flow to determine the hydroelectric power potential of poorly gauged basins, such as the precipitation–elevation, average precipitation, and average basin elevation methods. Results of these methods are compared with the available flow measurements. The poorly gauged Solaklı Basin, which is located in Trabzon, in the Eastern Black Sea Region of Turkey, is selected as the pilot area. The hydroelectric power potential of the planned small hydroelectric power plants in this area is estimated using different flow prediction methods.

WIT Transactions on the Built Environment, 1970

The maritime structures are subjected to the effects of nonbreaking, breaking and broken waves. Q... more The maritime structures are subjected to the effects of nonbreaking, breaking and broken waves. Quaywalls are designed by the hydrostatic pressures and dynamical forces of the wave motions; and Morison's forces to the legs are also taken into account if their combinations cause greater stresses. Members and fasteners of the quaywalls in harbour which are subjected to repeated variations and reversals of stresses shall be designed so that the maximum stress does not exceed the given allowable stresses, and the actual range of stress does not exceed the allowable fatigue stress range. The main objective of the paper is to present a procedure to calculate effective stress range for quaywall members under variable-amplitude randomsequence stress spectrums and to give analytical method for predicting fatigue life under variable amplitude stress spectrums from constant amplitude fatigue stress.

Su, dunyada insan hayatinin devami icin en onemli yasam gerekliliklerinin basinda gelen ancak oze... more Su, dunyada insan hayatinin devami icin en onemli yasam gerekliliklerinin basinda gelen ancak ozellikle son yillarda kuresel iklim degisikliginin etkisiyle tehlikeli bir bicimde azalmaya baslayan bir kaynaktir. Kuskusuz, suyu onemli kilan bir diger unsur da suyun ekonomik bir meta haline gelmesi, agir sanayi ve enerji uretiminde kullanilan temiz bir kaynak olmasidir. Dunyanin artan nufusu, uretim imkânlarinin artmasi gibi pek cok etken suya olan ihtiyaci surekli artirirken, kuresel iklim degisikligi ve cevreye verilen zarar ile birlikte su kaynaklari azaltmaya baslamis, bu durum da suyu her zamankinden daha onemli bir hale getirmistir. Calismada suyun onemine iliskin bilgilere yer verilmis, konu ile ilgili literatur incelenmis, ardindan da Turkiye acisindan Ortadogu bolgesindeki olasi riskler ele alinmistir.

Journal of Imaging Science and Technology, 2015

Simulation and modeling of turbulent flow, and of turbulent reacting flow in particular, involve ... more Simulation and modeling of turbulent flow, and of turbulent reacting flow in particular, involve solving for and analyzing time-dependent and spatially dense tensor quantities, such as turbulent stress tensors. The interactive visual exploration of these tensor quantities can effectively steer the computational modeling of combustion systems. In this article, the authors analyze the challenges in dense symmetric-tensor visualization as applied to turbulent combustion calculation; most notable among these challenges are the dataset size and density. They analyze, together with domain experts, the feasibility of using several established tensor visualization techniques in this application domain. They further examine and propose visual descriptors for volume rendering of the data. Of these novel descriptors, one is a density-gradient descriptor which results in Schlieren-style images, and another one is a classification descriptor inspired by machine-learning techniques. The result is a hybrid visual analysis tool to be utilized in the debugging, benchmarking and verification of models and solutions in turbulent combustion. The authors demonstrate this analysis tool on two example configurations, report feedback from combustion researchers, and summarize the design lessons learned.

Celal Bayar Üniversitesi Sosyal Bilimler Dergisi, 2014

hkmo.org.tr

Hidroloji ve su kaynakları çalışmalarında son yıllarda Uzaktan Algılama (UA) yöntemleri ile sağla... more Hidroloji ve su kaynakları çalışmalarında son yıllarda Uzaktan Algılama (UA) yöntemleri ile sağlanan uydu görüntüleri ve Coğrafi Bilgi Sistemleri (CBS) kullanılmaktadır. Uydu verileri ile yersel ölçümlere göre hızlı ve ekonomik çözümler elde edilebilmektedir. Bu çalışmada Solaklı Havzası için arazi kullanımının belirlenmesi amacıyla IRS P6, Sayısal Yükseklik Modeli (SYM)'nin oluşturulması amacı ile de stereo IRS P5 uydu verisi kullanılmıştır. SYM kullanılarak havzanın akış yönü ve yüzey akış haritaları oluşturulmuştur. Sonraki aşamada SYM, CBS yazılımda analiz edilerek havzanın sentetik drenaj ağı oluşturulmuştur. Bu drenaj ağı üzerinde, kolların kesişim noktaları üzerinde belirlenen istasyon noktalarını besleyen alt havzalar, CBS ortamında belirlenmiştir. Son aşamada alt havzalara ait topografik parametreler hesaplanmıştır. Havzada ve komşu havzalardaki meteoroloji istasyonlarının yağış verileri kriging yöntemi ile değerlendirilip havzaya ait eşyağış haritası oluşturulmuştur. Topografik parametreler ve eşyağış eğrilerinden elde edilen ortalama alansal yağış bilgileri çoklu regresyonla elde edilen akım denkleminde kullanılarak istasyon noktalarına ait akım değerleri hesaplanmıştır.

Sediment Transport, 2011

have limited widths and lengths. The flow and the hydraulic properties of the meandering river, t... more have limited widths and lengths. The flow and the hydraulic properties of the meandering river, the amount of sand moving along the bed, and the rate of bank erosion determine these limits. When a bend reaches this width, a chute forms and a new bend develops farther downstream. Distorted bends and natural cutoffs are caused by local changes in the character of bank materials. Several hypotheses have been brought forward to explain meandering. Meandering has been attributed to the earth's rotation; to the excessive slope and energy of a river (

Experiences: Aug. 1968 Apr. 1969 Engineer at State Water Supply Department, Trabzon. Apr. 1969 Se... more Experiences: Aug. 1968 Apr. 1969 Engineer at State Water Supply Department, Trabzon. Apr. 1969 Sept. 1970 Military Service, Ankara. Oct. 1970 July 1978 Graduate student and research fellow, İstanbul. July 1978 July 1979 Post-doctoral fellow at Colorado State Univ., USA. July 1979 July 1980 Post-doctoral fellow at Mississippi State Univ., USA. July 1980 Apr. 1982 Assistant Professor at Tech. Univ. of Istanbul. Apr. 1982 Nov. 1988 Associate Professor at Tech. Univ. of Istanbul. Nov. 1988 Jan. 1993 Professor at Technical Univ. of Istanbul. Jan. 1993 Sept. 1993 Dean of Engineering Faculty at Sakarya Univ. Sakarya. Sept. 1993 Feb. 1995 Professor at Tech. Univ. of Istanbul, İstanbul. Feb. 1995 Feb. 1996 Professor, Eastern Mediterranean Univ., Cyprus. Feb. 1996 – May 2003 Professor at Technical University of Istanbul; Istanbul. May 2003 – Oct. 2009 Head of Hydraulic Div. at Tech. Univ. of Istanbul; İstanbul. Mar. 2009 – Apr. 2014 Member of Board of Management at İSKİ, İstanbul Jan. 2015 – ...

This article provides an overview of the Sapanca Lake water capacity management program,including... more This article provides an overview of the Sapanca Lake water capacity management program,including a description of the hydrologic conditions in the region, an overview of the lake storage system, and its water use control capabilities, and a description of forecasting procedures and water-use control operating strategy. The development and implementation of water capacity management program, and its role in reducing water amount at the Sapanca valley are also presented. The article closes with a discussion of the role of water management advances on future operations. As a conclusion, withdrawn water differs with the months. Because Sapanca Lake interact with ground water in three basic ways: some receive ground water inflow throughout their entire bed, some have seepage loss to ground water throughout their entire bed, but Sapanca Lake receive ground water inflow through part of their bed from Sakarya River, which is situated 5 km away from the eastern part of the Sapanca District ...

Closed - form mathematical models are developed for the rate of development of secondary current,... more Closed - form mathematical models are developed for the rate of development of secondary current, and for bed topography in meandering, erodible-bed streams of arbitrary plan form. The formulations utilise conservation of flux-of-moment-of - momentum as the additional relation required to complete the formulation for the radial water-surface slope and radial bed- shear stress. The flow distribution is computed utilising the secondary-flow and bed topography. In this way, the secondary-flow velocity calculation is uncoupled from the calculation of the radial mass-shift velocity and streamwise velocity distributions, which were obtained from the depth-integrated equations expressing conservation of mass and streamwise momentum. The numerical model developed was tested using the hydraulic and sediment-transport characteristics of flume experiments. Generally good agreement was obtained between measured and computed distributions of flow depth and depth-averaged oscillatory shear stress...

Lateral vibration of underwater suspended pipeline was investigated for the case of pipeline osci... more Lateral vibration of underwater suspended pipeline was investigated for the case of pipeline oscillation due to vortex shedding. Firstly, tension force was defined at the connection legs on sea bottom. To define the dynamical equation the analogy of the Mathieu equation was applied, meanwhile Ince-Strutt diagram was used for its solution. As a numerical example we used the behavior of pipeline in a project between Turkey and North Cyprus in the East Mediterranean Sea. Good agreement was found between the theoretical results and experimental data of Danish Hydraulic Institute (DHI

Journal of Geographical Research, Mar 14, 2019

In this research it is established a classification system by which to characterize atmospheric c... more In this research it is established a classification system by which to characterize atmospheric conditions, specifically those related to winter extra tropical storms and fair weather. Numerous classification schemes have been proposed to categorize atmospheric conditions in a variety of environments-however, since meteorological processes are inherently complicated, these are of necessity based on criteria that suit a particular purpose. The system employed in this project was ultimately designed to differentiate between: 1. fair weather and storm conditions; 2. different phases of extratropical storms; 3. extratropical storms of different intensities and synoptic types.

Public Sector Crisis Management, 2020

Monte Carlo in Monaco is given to the theory for mathematics, whose simulation process involves g... more Monte Carlo in Monaco is given to the theory for mathematics, whose simulation process involves generating chance variables and exhibiting random behaviours in nature. This simulation is a powerful statistical analysis tool and widely used in both non-engineering fields and engineering fields for new perspectives. This simulation has been applied to diverse problems ranging from the simulation of complex physical phenomena such as atom collisions, to the simulation of river boundary layers as meanders and Dow Jones forecasting. It can deal with many random variables, various distribution types and highly nonlinear engineering models, while Monte Carlo is also suitable for solving complex engineering problems in two areas which are varying randomly. Monte Carlo simulation is given as an application for hydrogen energy potential determination.

Journal of Geographical Research, 2019

Bank full discharge is generally considered to be the dominant steady flow which would generate t... more Bank full discharge is generally considered to be the dominant steady flow which would generate the same regime channel shape and dimensions as the natural sequences of flows would. This is because investigation on the magnitude and frequency of sediment transport have determined that for stable rivers the flow which in the longer term transports most material has the same frequency of occurrence as bankfull flow. For stable gravel-bed rivers, this is considered to be the 1.5-year flood.

CLEAN - Soil, Air, Water, 2009

DESALINATION AND WATER TREATMENT

The efficacy of nanofiltration (NF) in removing sulfate from a high sulfate content (370-460 mg/L... more The efficacy of nanofiltration (NF) in removing sulfate from a high sulfate content (370-460 mg/L) surface water was investigated. NF tests were carried out using a laboratory-scale cross-flow NF module operated in total-recycle (full-recycle) mode. Membranes of varying characteristics; namely, DK-NF (Desal DK: GE Osmonics, USA), DL-NF (Desal DL: GE Osmonics, USA), and NF270 (Dow Filmtec Co., USA) were tested, and the effects of main operational parameters of cross-flow velocity, trans-membrane pressure, and pretreatment on permeate flux and sulfate removal were evaluated. The NF270 membrane exhibited the highest permeate flux and was found to be the best of the three membranes tested, with over 98% sulfate removal. The DK-NF membrane, which was poor in performance with a high flux decline, provided the lowest sulfate removal, lowest permeate flux, and highest fouling. Microfiltration (2.5-µm), as pretreatment, provided no considerable improvement in permeate flux. When the effects of operational parameters on NF performance using the DL-NF membrane were sought, it appeared that permeate flux, and sulfate removal efficiency did not change at all with trans-membrane pressure and cross-flow velocity. The study is expected to provide useful information about the NF of drinking water with high sulfate content in the future.

Simulation Foundations, Methods and Applications

The use of computational simulation in science is now pervasive. However, while model development... more The use of computational simulation in science is now pervasive. However, while model development environments have advanced to a degree that allows scientists to build sophisticated models, there are still impediments that limit their utility within the broader context of the scientific method. Despite availability of effective tools that assist scientists in routine aspects of scientific workflow management and analytics, other steps, including explanation, evidential reasoning, and decision-making, continue to limit the process of causal reasoning in knowledge discovery and evaluation. This chapter examines the types, functions, and purposes of models in relation to the scientific method, identifies the issues and challenges pertaining to information abstraction and cognitive support for computational discovery, and delineates a model-driven cognitive systems approach for simulation-based science.

The development of the dunes are governed by the effects of turbulence. Turbulence is a type of f... more The development of the dunes are governed by the effects of turbulence. Turbulence is a type of fluid flow that is strongly rotational and apparently chaotic. Turbulence separates nearby parcels of air and thus mixed fluid properties . The evolution of sand dunes is determined by the interactions between the atmosphere, the surface and the transport and deposition of sand. We are concerned with this physical process and its computational simulation from three perspectives; namely, (1) flow structure; (2) sand transport and deposition and (3) interactions between flow structure and sand transport-deposition, which determine the dune morphology.

Motivation and problem-domain preferences of scientists can affect aggregate level emergence and ... more Motivation and problem-domain preferences of scientists can affect aggregate level emergence and growth of problem domains in science. In this study, we introduce an agent-based model that is based on information foraging and expectancy theory to examine the impact of rationality and openness on the growth and evolution of scientific domains. We simulate a virtual socio-technical system, in which scientists with different preferences search for problem domains to contribute knowledge, while considering their motivational gains. Problem domains become mature and knowledge spills occur over time to facilitate creation of new problem domains. We conduct experiments to examine emergence and growth of clusters of domains based on local interactions and preferences of scientists and present preliminary qualitative observations.

International Journal of Science and Research (IJSR)

Using intensive mathematical iterations it is possible to apply fuzzy method to the river enginee... more Using intensive mathematical iterations it is possible to apply fuzzy method to the river engineering problems like sedimentation. In the previous methods it is useful to apply the fuzzy logic with quick development of computer models in neural network systems. Fuzzy has resulted in the mistaken suspicion that Fuzzy Logic is somehow less exacting than traditional logic. In this research instead of traditional interpretation of sedimentation it will used Fuzzy logic to obtain the disposal of suspended sediment at the meandering river regimes. For finding the output variables it will be defined the input and at the end using fuzzy logic procedure which is a technique that facilitates the control of a complicated system (in our research the meandering stream control with water and sediment discharge which is dependent on several parameters) without knowledge of its mathematical description. The steps will be descriped in detail.