Time Domain Seakeeping Computation (IR_RANKINE)
Overview:
IR_RANKINE is a time domain seakeeping program based on 3D Numerical wave Tank method following a simplified variant of mixed Eulerian Lagrangian scheme. Its primary purpose is to compute nonlinear wave induced loads and motions for all range of forward speeds in a realistic seaway. In the developed program the ambient incident wave can be defined as linear waves, nonlinear waves, long crested and short crested waves. The developed numerical program assumes Neumann Kelvin linearization for steady wave potential solution and uses a polynomial curve fitting technique to determine longitudinal derivative of velocity potential and free surface elevation. Equation of motion and the boundary integral equation are solved in time domain using a higher order time marching scheme such as 4th order Runge Kutta or Adams-Bashforth-Moulton method to determine the body displacements and time evolving free surface elevations.
This State-of-the-art tool offers a distinct advantage in conducting nonlinear seakeeping analysis, a crucial aspect for optimizing fine ship hulls. With its exceptional capabilities, IR_RANKINE enables to compute ship responses with 3D irregular sea state modelling, facilitate novel design assessments, development and refinement of ship rules. This tool also enables to perform sophisticated assessments including parametric rolling, side-by-side- offloading, and Direct Stability Assessment (DSA) under the second Generation of Intact Stability.
Key Features:
- Linear and non-linear ship motion.
- Long duration time domain simulations.
- Long crested and short crested waves
- Irregular sea state
- Parametric roll motion simulations
- Steady wave resistance
- Added wave resistance
- Multihull seakeeping
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(b)
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Figure: (a) Steady wave pattern (b) Ship in the regular wave field, λ/L = 1.0 (c) Ship encountering the irregular waves, Hs = 9.5m, Tz = 16.5s