Devrim Bülent DANIŞMAN, Ömer GÖREN

Gemi dalga direncinde lineer olmayan etkilerin hesaplamalı olarak incelenmesi

Gemi dalga direncini doğru olarak hesaplayabilmek gemi-form dizaynı açısından vazgeçilmez bir öneme sahiptir. Bu çalışmada gemi etrafındaki akışta lineer olmayan serbest su yüzeyi sınır koşullarını kullanan bir vöntem geliştirilmiştir. İteratif bir algoritma ile çalışan bu yöntemde lineer olmayan serbest su yüzeyi koşulları, deforme olmuş serbest su yüzeyi üzerinde uygulanmaktadır. İterasyon adımlarında gemi ile serbest su yüzeyinin tam bir ara kesitinin alınması sayesinde geminin ıslak alanı gerçekle olduğu gibi alınabilmiştir. Çalışmanın sonuçlarının irdelenmesi amacıyla örnek bir gemi geometrisi (Seri 60, Cn=0.60) alınmış ve sonuçlar deneylerle karşılaştırmalı olarak gösterilmiştir. Yapılan karşılaştırmalar, geliştirilen yöntemle elde edilen sonuçların deneysel sonuçlarla uyum içerisinde olduğunu göstermektedir.

Computational investigation of non-linear effects in ship-wave resistance

Computing ship-wave resistance has an indispensable importance in hull form design, in this study to calculate ship-wave resistance more accurately a method which utilizes non-linear free surface boundary conditions for the flow around the hull is developed. In this method the free surface boundary conditions are imposed on the deformed free surface iteratively. At the iteration steps, by the help of using interface of deformed free surface and ship-hull geometry, the wetted surface involved in the compulations has been taken more realistic. Using exact wetted surface of the ship let determine the effect of the ship's geometry above the still water level on the wave resistance. To show the results of the study a reference geometry (Series 60, $C_B$=0.60) is put to the computations and the results are shown comparatively. Comparisons made show the results obtained from the method developed are close to those of obtained from the experimental studies. As an application of a hull form design problem, effects of changes in the flare geometry on the flow around the ship has been computed by using the algorithm developed. This application proves that the algorithm developed in this study can be used as a design tool for optimizing the geometry above still water level.

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