Riser VIV analysis by a CFD approach
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In this paper, we present a CFD approach for riser vortex induced vibration (VIV) analysis in uniform current. The riser has a L/D of 1400, and is partitioned into 30 segments with uniform current specified on each segment. The drag and lift coefficients of each segment are then calculated using an unsteady Navier-Stokes numerical method on an overset (Chimera) grid system. These drag and lift coefficients are assembled to determine the riser displacements for each riser segment. The riser motion equation is expressed through riser modal shape superposition, and integrated in time domain by using Runge-Kutta scheme. At each time step the data grids for each riser segment are updated according to the riser's instantaneous displacements. The predicted riser VIV results are compared to the experimental data and previous publications. General agreements are observed. It is concluded that the present numerical method is valid and effective for riser VIV prediction. Copyright 2007 by The International Society of Offshore and Polar Engineers(ISOPE).