A systematic approach to riser VIV response reconstruction

Optimal lift force coefficient databases from riser experiments

“…In a similar manner, allowing IL motions has the effect of adding another peak in the C lv database (Marcollo and Hinwood, 2006). Recent improvements in estimating the vortexinduced motion of an entire marine riser using data from a limited number of sensors [refer to Mukundan et al (2008a)] have improved our capability to closely observe and reverse engineer the hydrodynamic data. However, obtaining similar extensive databases from field experimental data is not straightforward and it is often possible to construct a small subset of all the combinations of V r and A Ã available in the Gopalkrishnan databases.…”

“…Given experimental data from sensors located along the riser, we identify a statistically stationary segment of experimental data using scalograms (Mukundan et al, 2008b). A response reconstruction is then performed to obtain the displacement time series at any point along the riser yðz; tÞ [refer to Mukundan et al (2008a)] using the Fourier decomposition method, as it allows for confidence during the reconstruction. We compute the Fourier transform of the time signals at every location along the span to obtain the Fourier coefficientsŷðz; oÞ.…”

“…For the problem at hand, a variant of the simulated annealing method was chosen due to its simplicity in addition to the performance characteristics. For a detailed discussion on simulated annealing method refer to Morgan and Rao (2006) or Mukundan et al (2008a). The input to a simulated annealing algorithm is a range for each parameter within which the solution is expected to lie, and the output is the parameter-setp opt which minimizes the error metric over the parameter range.…”

“…The same dataset used for benchmarking the response reconstruction, mentioned in Mukundan et al (2008a), was used to benchmark the optimal data assimilation algorithm. The benchmark dataset was constructed from one of the VIVA modes.…”

Effect of bidirectional internal flow on fluid.structure interaction dynamics of conveying marine riser model subject to shear current

“…Although there are so many works carried out for the VIV research relating flexible pipe/riser systems which are subject to uniform, shear or even nonlinear-patterned external current, hitherto, the contribution of internal progressive flow to FSI response of flexible riser had rarely been considered. In fact, the curvature of flexible pipes/risers and the relative motion of axial internal flow to the timedependent pipe/riser motion are crucial factors to the safety design of marine riser system (Mukundan, et al, 2010). According to the dynamics principle, the internal progressive flow experiences centrifugal and Coriolis accelerations, when conveying along the curved path of deflected pipe/riser (Païdoussis, 1998).…”