Advanced two- and three-dimensional tsunami models: Benchmarking and validation

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Tezin Türü: Doktora

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2017

Öğrenci: DENİZ VELİOĞLU

Danışman: AHMET CEVDET YALÇINER

Özet:

Field observations provide valuable data regarding the nearshore tsunami impact, yet only in inundation areas where tsunami waves have already flooded. Therefore, tsunami modeling is essential in order to understand tsunami behavior and prepare for tsunami inundation. Analytical and numerical methods are widely applied to predict tsunami motion and inundation characteristics. On the other hand, the data obtained from field surveys and laboratory experiments are generally used for validation and performance assessment of numerical models. Nonlinear forms of two-dimensional depth-averaged shallow water equations are the most common tools that are used to estimate tsunami wave transformation and inundation. However, they may not suffice when three-dimensional flow characteristics, such as strong turbulent motion, develop in shallow water zones due to various nearshore conditions. In this respect, the performance of numerical codes that are capable of predicting tsunami motion in shallow water zones gains more importance. There are numerous numerical codes to be used for simulating tsunami motion and inundation. In this study, two numerical codes, NAMI DANCE and FLOW-3D®, are selected for validation and performance comparison. NAMI DANCE solves nonlinear forms of two-dimensional depth-averaged shallow water (2D-NSW) equations in long wave problems, specifically tsunamis. FLOW-3D® simulates linear and nonlinear propagating surface waves as well as long waves by solving three-dimensional Reynolds-averaged Navier-Stokes (3D-RANS) equations. The codes are validated vi and their performances are compared via analytical benchmarking, experimental benchmarking and field benchmarking. The results are assessed according to the accuracy and run time of the solutions. The variations between the numerical solutions of two- and three-dimensional models are evaluated through statistical error analysis. By referring to the validity range determined by these comparisons, recommendations pertinent to applying relevant models to various tsunami problems are made.