Development of a numerical 2-dimensional beach evolution model

This paper presents the description of a 2-dimensional numerical model constructed for the simulation of beach evolution under the action of wind waves only over the arbitrary land and sea topographies around existing coastal structures and formations. The developed beach evolution numerical model is composed of 4 submodels: a nearshore spectral wave transformation model based on an energy balance equation including random wave breaking and diffraction terms to compute the nearshore wave characteristics, a nearshore wave-induced circulation model based on the nonlinear shallow water equations to compute the nearshore depth-averaged wave-induced current velocities and mean water level changes, a sediment transport model to compute the local total sediment transport rates occurring under the action of wind waves, and a bottom evolution model to compute the bed level changes in time based on the gradients of sediment transport rates in cross-shore and longshore directions. The developed models are applied successfully to the SANDYDUCK field experiments and to some conceptual benchmark cases including simulation of rip currents around beach cusps, beach evolution around a single shore perpendicular groin, and a series of offshore breakwaters. The numerical model gave results in agreement with the measurements both qualitatively and quantitatively and reflected the physical concepts well for the selected conceptual cases

Ortalama Su Seviyesi Değişimlerinin Taş Dolgu Kıyı Koruma Yapılarının Tasarımına ve Performansına Etkisi

Gel-git, mevsimsel değişiklikler, dalga kabarması/alçalması, fırtına kabarması ve küresel ısınmaya bağlı su seviyesi değişimleri sonucunda ortalama su seviyesinde gözlenen değişimler, taş dolgu kıyı koruma yapılarının tasarımlarının ve performanslarının değerlendirilmesi ile doğrudan ilgilidir. Bu tip yapılar için en kritik su seviyesi, yaygın olarak en yüksek su seviyesi tanımı ile kullanılmaktadır. Ancak, Kıyı Yapıları Planlama ve Tasarım Teknik Esasları’nda [1] koruma yapısında kullanılacak taşların kütlelerinin belirlenmesi için en kritik su seviyesinin en düşük su seviyesi ile en yüksek su seviyesi arasında ortaya çıkabileceği belirtilmiştir. Bu çalışmada taş dolgu kıyı koruma yapılarının tasarım derinliğinin belirlenmesinde kullanılan farklı yaklaşımların koruma tabakası taş kütlesi ile serbest kret kotuna olan etkisi incelenmiştir. Bu amaçla Karadeniz, Ege Denizi ve Akdeniz’de birer proje alanı seçilmiş ve bu projelerdeki yapıların ekonomik ömürleri boyunca gözlenebilecek tüm su seviyelerinde koruma tabakası taş kütlesi ile serbest kret kotu hesaplanmıştır. Seçilen projeler için daha düşük su seviyelerinde daha yüksek su seviyelerine göre %60’a varan oranlarda daha büyük taş kütlesi bulunmuştur. Çalışma sonuçları, en yüksek su seviyesinden daha kritik bir su seviyesinin, düşük su seviyesi ile en yüksek su seviyesi arasındaki herhangi bir su seviyesinde de oluşabileceğine örnek oluşturmaktadır. Buna bağlı olarak, seçilen kritik su seviyesi değeri ile koruma tabakası taş kütlesi hesaplama yöntemlerinin ilişkisi tartışılmış ve yapının ekonomik ömrü boyunca oluşabilecek tüm su seviyelerinin tasarım derinliği belirlenirken göz önünde bulundurulması önerilmiştir.&nbsp;</p

Numerical simulation of scour and backfilling processes around a circular pile in waves

This study continues the investigation of flow and scour around a vertical pile, reported by Roulund et al. (2005). Flow and scour/backfilling around a vertical pile exposed to waves are investigated by using a three-dimensional numerical model based on incompressible Reynolds averaged Navier-Stokes equations. The model incorporates (1) k-omega turbulence closure, (2) vortex shedding processes, (3) sediment transport (both bed and suspended load), as well as (4) bed morphology. The numerical simulations are carried out for a selected set of test conditions of the laboratory experiments of Sumer et al. (1997, 2013a), and the numerical results are compared with those of the latter experiments. The simulations are carried out for two kinds of beds: rigid bed, and sediment bed. The rigid-bed simulations indicate that the vortex shedding for waves around the pile occurs in a "one-cell" fashion with a uniform shedding frequency over the height of the cylinder, unlike the case for steady current where a two-cell structure prevails. The rigid-bed simulations further show that the horseshoe vortex flow also undergoes substantial changes in waves. The amplification of the bed shear stress around the pile (including the areas under the horseshoe vortex and the lee wake region) is obtained for various values of the Keulegan-Carpenter number, the principal parameter governing the flow around the pile in waves. The present model incorporated with the morphology component is applied to several scenarios of scour and backfilling around a pile exposed to waves. In the backfilling simulations, the initial scour hole is generated either by a steady current or by waves. The present simulations indicate that the scour and backfilling in waves are solely governed by the lee-wake flow, in agreement with observations. The numerical model has proven successful in predicting the backfilling of scour holes exposed to waves. The results of the numerical tests indicate that the equilibrium depth of scour holes is the same for both the scour and the backfilling for a given Keulegan-Carpenter number, in full agreement with observations

Kıyılarda iklim değişikliğine karşı kumlanma modeli destekli kırılganlık analiz projesi-KIDEKA

TÜBİTAK MAG15.03.201

Aesthetics of self-scaling: parallaxed transregionalism and Kutluğ Ataman's art practice

This article examines relations of ethnography, contemporary art-practice, globalisation and scalar geopolitics with particular reference to Kutluğ Ataman’s artworks. Having been shortlisted for the Turner Prize at the Tate and awarded the prestigious international Carnegie Prize in 2004 with his forty-screen video installation Küba (2004), Ataman became an extremely well-known, globally acclaimed artist and filmmaker. Self-conscious of their global travel and critically attentive to the contemporary ethnographic turn in the visual arts scene, Ataman’s video-works perform a conscientious failure of representing cultural alterity as indigeneity. Concentrating on the artist’s engagement with ethnography, this article contains three main parts. Analyses of the selection of videos in each part will give an account of different scalar aspects of Ataman’s artworks. It will first revisit a previous study (Çakirlar 2011) on the artist’s earlier work of video-portraits including Never My Soul! (2002) and Women Who Wear Wigs (1999). A detailed discussion of Küba follows, which may be taken as the ‘hinge - work’ in Ataman’s oeuvre that marks a scalar transition in his critical focus - from body and identity to community and geopolitics. The discussion will then move to a brief analysis of the series Mesopotamian Dramaturgies, including the screen-based sculptures Dome (2009), Column (2009), Frame (2009), English as a Second Language (2009), and The Complete Works of William Shakespeare (2009). Rather than addressing scale as a differential concept, this article aims to demonstrate the ways in which Ataman’s art-practice produces self-scaling, self-regioning subjects that unsettle the hierarchical constructions of scale and facilitates a critique of the scalar normativity within the global art world’s regionalisms and internationalisms