Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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Article Citation - WoS: 4Citation - Scopus: 4Destratification of Thermally Stratified Water Columns by Air Diffusers(Elsevier, 2023) Elçi, Şebnem; Hazar, Oğuz; Bahadıroğlu, Nisa; Karakaya, Derya; Bor, AslıThis study aims at improving the understanding in order to optimise an aeration system for artificial destratification to control cyanobacteria growth in the reservoirs. Previous applications for artificial destratification in reservoirs were based on installations based on computational methods, where neither the effect of air bubble size and configuration nor the effect of air density in the bubble plume could be investigated. This study seeks for an optimized design with the help of experimental and numerical analyses. In order to perform experimental studies, a novel water tank enabling the heating/cooling of the water column as desired and a diffuser system were manufactured. During the experimental studies, effect of bubble size, bubble slip velocity, and other parameters of air diffuser on destratification efficiency were investigated. Based on the nondimensional parameters, a new destratification efficiency formula is obtained by the Genetic Algorithm (GA) approach. Additionaly, the hydrodynamics of the water tank during the mixing process by air diffuser was simulated via 3D numerical model and validated with experimental results. The Eulerian multiphase model with the ‘degassing’ boundary condition and k-ω turbulence model are found to be suitable for the purposes of the study. Based on the error analysis of comparisons of the model and observations, the best configuration of air diffuser is proposed, and the numerical model is found to be successful in simulating the destratification of thermally stratified water columns by air diffuser.Article Citation - WoS: 1Citation - Scopus: 1Comparison of the Predicted and the Observed Wave Spectral Parameters During the Storms at Filyos Coasts, the Southwestern Black Sea(Elsevier, 2022) Öztunalı Özbahçeci, Bergüzar; Güler, MuzafferIn-situ wave measurement data are mainly used to validate the bulk wave parameters predicted by numerical models. Although the frequently used third-generation wave models are spectral models, determination of various spectral parameters and validation with the observed data are not common. This study covers the spectral analysis of selected storm records of a nearshore wave measurement campaign carried out at Filyos coasts with the complex bottom topography in Turkey, Southwestern Black Sea. The bulk wave and the spectral parameters are also calculated by a third-generation nearshore wave model, SWAN (Simulating Waves Nearshore), forced by the ERA5 offshore wave data, which is the newest re-analysis of the European Centre for Medium-Range Weather Forecasts (ECMWF) for the selected storms. Before using ERA5 offshore wave data, they are calibrated by the wave data of the satellite radar altimeter. In-situ measured bathymetry data are used in the SWAN model. Observed and predicted bulk wave and spectral parameters are compared, and the statistical error measures are calculated not only for the significant wave height, the peak period, and the peak wave direction but also for the three different spectral periods, three different frequency width parameters, a directional width and, a spectral peakedness parameter for the first time. Low values of statistical error measures show that the current wave predictions have a good agreement with the observed ones in terms of the significant wave height, Hs, and the peak period, Tp. However, the SWAN model predicts a slightly narrower frequency and directional spectrum with higher peaks, although the error measures are low. Moreover, SWAN can not predict the wide range of spectral shape occurrences that the observed spectra have. The development of the various spectral parameters during the storms is also investigated for the first time. It is found that the frequency and directional spreading of the observed spectra become wider and unsharpened in the late stages of the storm compared to the early stages. However, the same tendency is not observed clearly in the predicted directional spreadingArticle Citation - WoS: 24Citation - Scopus: 27Drought Assessment in the Aegean Region of Turkey(Springer, 2022) Mersin, Denizhan; Gülmez, Ayşe; Safari, Mir Jafar Sadegh; Vaheddoost, Babak; Tayfur, GökmenDrought indices are commonly used to monitor the duration and severity of droughts. In this regard, the continuously changing climate regardless of its cause or effect pushes the limit of the water deficit through time and space. Izmir is a raising city in Turkey, which owns various water resources including but not limited to seashores, lakes, river streams, and groundwater aquifers. In this study, the long-term precipitation and temperature records from 14 meteorological stations between 1973 and 2020 (for 47 years) are used to investigate the drought characteristics in Buyuk Menderes, Kucuk Menderes, and Gediz basins located in the Aegean region of Turkey. For this, the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI), Percent of Normal (PNI), and the so-called Discrepancy Precipitation Index (DPI) are used with consideration to 1-, 3-, 6-, and 12-month moving averages to investigate the drought patterns. Results showed that the monthly indices depict very similar results for the entire region. However, in the 1980s and 2010s droughts were more severe than the rest of the historical records. When the moving average operator is implemented in the analysis (3-, 6- and 12-month periods), neither SPI nor the SPEI showed the same results at any stations. It is illustrated that the periods of severe and normal drought have occurred in the past, yet the indices that are obtained using average values are generally within the normal limits, but extreme values (extremely arid or extremely wet) occurred occasionally. It is also concluded that although there is a similarity between the implemented indices, the DPI and PNI depict the highest resemblance.Article Citation - WoS: 2Citation - Scopus: 3Site Assessment of Surface Texture and Skid Resistance by Varying the Grit Parameters of an Sma(American Society of Civil Engineers (ASCE), 2022) Gökalp, İslam; Uz, Volkan Emre; Saltan, Mehmet; Tepe, MehtapFor the sale operation of vehicles, pavement should provide adequate skid resistance, which can be achieved by using high polishing-resistant aggregate in wearing courses. However, supplying high-quality aggregate is not always feasible due to high transportation costs. For this reason, a method called gritting was adapted to meet the Highway Technical Specification (HTS) of Turkey in 2013. According to the method, for certain parts of the country, the wearing course can be constructed with local aggregates that have minimum polished stone value (PSV) of 40 (PSV >= 40), but, in this case, the surface must be covered with a high polishing-resistant aggregate (PSV >= 50), after the rollers' first pass. The objective of this study was to improve the present gritting method by investigating the effect of grit parameters on pavement performance under real traffic conditions. In this regard, during its construction, the wearing course of 0-51 Highway was gritted with different aggregate types (slags and natural), sizes (1-3; 1-5 mm), spreading amount (1.5; 2; 2.5 kg/m(2)), and spreading time (before and after the first pass of a roller) on eight test sections. Then, the macrotexture and skid resistance performance of these sections were evaluated under real traffic and environmental conditions for longer than 4 years. Changes in surface texture and skid resistance with respect to traffic were determined for each section. The results showed that higher skid resistance values were obtained at the sections gritted with metallurgical slags. Additionally, the sections gritted with 1-5 mm aggregates had better skid resistance than those gritted with 1-3 mm, while the change in mean texture depths were not very significant.Article Citation - WoS: 1Citation - Scopus: 1A Magnetically Driven Elastic Rod Type Bi-Directional Swimmer at Stokes Flow(Springer, 2022) Özdemir, İzzetIn this paper, a flexible rod type micro-swimmer is proposed which achieves swimming direction reversal on the fly by forming a chiral helix-like geometry through external magnetic excitation. Furthermore an accompanying low Reynolds number flow-structure interaction analysis framework is developed which effectively combines a geometrically non-linear shear deformable beam model with regularized Stokeslet method in a monolithic implicit solution algorithm. This framework is used to investigate the basic characteristics of the proposed micro-swimmer in terms of dimensionless groups reflecting the interplay between different forces involved.Article Citation - WoS: 10Citation - Scopus: 12Impacts of Construction of Dam on the Flow Regimes and Water Quality: a Case Study From Turkey(Springer, 2022) Bor, Aslı; Elçi, ŞebnemDam construction has important positive and negative effects on the environment, including physical changes of the riverbed morphology, changes in sediment transport patterns and water quality, and the river ecosystem in general. The primary objective of this study is to present a methodology to assess the impacts of construction and operation of Çine Dam, in Aydin, Turkey, on the river flow regimes, sedimentation, and water quality of the downstream reach of Büyük Menderes River. Construction of the dam significantly reduced the sediment load from the Çine tributary to the main reach, as expected. To evaluate changes in the water quality of the Çine River, five different water quality index methods are compared before and after the dam operation: Weighted Arithmetic Index (WAI-WQI), Canadian Council of Ministers of the Environment Water Quality Index (CCME-WQI), Universal Water Quality Index (UWQI), Oregon Water Quality Index (OWQI) and Aquatic Toxicity Index (ATI). ATI and CCME-WQI methods are found to be more appropriate for the 10-year water quality assessment of the river.Article Citation - WoS: 6Citation - Scopus: 6Valuing Groundwater Heritage: the Historic Wells of Kadıovacık(Springer, 2021) Yüceer, Hülya; Baba, Alper; Özcan Gönülal, Yasemin; Uştuk, Ozan; Gerçek, Deniz; Güler, Selen; Uzelli, TaygunThe consideration of the subject of water resources, seen as a part of cultural heritage, generally includes water-related architectural structures such as bridges, aqueducts, and cisterns. Groundwater resources and related structures, however, receive little attention as heritage assets, and they are mostly forgotten together with the valuable information they hold. In this sense, this study aims to provide an accurate assessment of groundwater heritage and to suggest proposals for conservation through the case of the historic wells of Kadıovacık village in the Urla district of İzmir. Although the region where the village is located is rich in groundwater resources, the residents have suffered from drought for ages due to the specific geological characteristics of the Kadıovacık polje. The limited amount of water resources in Kadıovacık village have karstic characteristics and have shaped the life and topography of the region. To access and harvest this limited groundwater, a group of wells had been constructed on the ridge of the hill. These wells have been idle since 1980s with the supply of city main water. In line with the aim, a comprehensive heritage valuation by an interdisciplinary group of experts is essential to reveal the significance of the relatively humble wells. Accordingly, a multi-method system is used, including historical, social, cultural, architectural, geological, hydrogeological, and environmental aspects. The results show that although the wells are generally considered to be less important as heritage assets in terms of their physical features, an in-depth evaluation demonstrates their high significance for the village community.Article Citation - WoS: 3Citation - Scopus: 3A Quality Assessment of Public Water Fountains and Relation To Human Health: a Case Study From Yozgat, Turkey(John Wiley and Sons Inc., 2019) İritaş, Servet Birgin; Türksoy, Vugar Ali; Deniz, Serdar; Koçoğlu, Serhat; Kırat, Güllü; Demirkesen, Ali Can; Baba, AlperPublic fountains are very common and everyday people appreciate the benefits a water fountain can bring. However, consumption of public fountain water in some country has decreased because of growing concerns that constituents in fountain water may have adverse effects on health. A few studies have examined the safety of public fountains, proposing only limited evidence of fountain-related health issues in Turkey. Most of these public fountains are sourced from natural springs in Turkey. In this study, a 177 fountain water and 32 rock samples were analysed for source and quality of water. The geology of the region has the direct impact on the quality of the public fountain water. The results indicate that the level of some elements exceeded the limit values determined by WHO and US.EPA. The most striking high values were observed for iron (Fe), nickel (Ni), aluminum (Al), arsenic (As) and bromine (Br) concentrations.