Original scientific paper
https://doi.org/10.21278/brod68203
PREDICTION OF THE VERTICAL MOTIONS OF DTMB 5415 SHIP USING DIFFERENT NUMERICAL APPROACHES
Ferdi Cakici
; Naval Architecture and Maritime Faculty, Yildiz Technical University, Istanbul, Turkey
Omer Faruk Sukas
; Naval Architecture and Maritime Faculty, Yildiz Technical University, Istanbul, Turkey
Omer Kemal Kinaci
; Naval Architecture and Maritime Faculty, Yildiz Technical University, Istanbul, Turkey
Ahmet Dursun Alkan
; Naval Architecture and Maritime Faculty, Yildiz Technical University, Istanbul, Turkey
Abstract
Recent developments in Computational Fluid Dynamics (CFD) enabled common access for researchers and thus offers solutions to various complex problems in many different fields. With this motivation, in this study, two kinds of numerical methods were employed to investigate the vertical motions in variable regular waves. While the potential method is commonly known as linear “strip theory”, the viscous approach is (the state of the art) named as URANS (Unsteady Reynolds Averaged Navier Stokes) solver which has a fully non-linear base. DTMB 5415 ship model form was selected for a series of computational works. Computational study was carried out to understand the seakeeping behaviour of the displacement hull for the stationary case Fn=0 and a high speed case Fn=0.41. The RAO (Response Amplitude Operator) graphs for the coupled heave - pitch motions and CoG (center of gravity) vertical acceleration of the hull were generated for five encounter frequencies. Results were validated with experiments and comparisons were made between the two numerical approaches with the help of RAO graphs. Obtained results showed that the limitations of the strip theory pose a handicap as the assumptions involved in the theory narrow down its application. The nonlinear viscous URANS approach is generally a better option returning closer results to experiments in a wide Froude number range but on the other hand it does not possess the practicality of the strip theory.
Keywords
Seakeeping; CFD, Strip Theory; URANS, ship motions
Hrčak ID:
174120
URI
Publication date:
30.6.2017.
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