Deepwater field developments are usually associated with large submarine packages to be installed such as suction anchors, manifolds and other subsea equipment.
Key data for the lowering operation engineering are the added mass and drag coefficients of the package, which is usually a complex structure made of plates (mudmat, drop object protection…), piping and miscellaneous equipment. To extract these hydrodynamics coefficients, it is usual industry practice to consider the package overall volume or to sum the individual components coefficients which may lead to very different results.
Experimental investigations on generic complex structures have been conducted within the CITEPH project “Offshore installation of heavy package – phase II”, with the aim of better understanding the hydrodynamics coefficients to be used for the design.
This paper presents the work that has been performed during this joint industry project, in 2010/2011, with the support of TOTAL, TECHNIP, SAIPEM and DORIS Engineering, on shielding effect. In particular, model tests set-up and main results are discussed. The trends that have been found and the empirical laws that have been established as functions of dimensionless numbers are also presented.