Abstract
This paper presents a numerical algorithm used together with a Finite-Element based Vortex-Induced Vibration (VIV) prediction software VIVANA to obtain a hydrodynamic force coefficient database based on response measurements of flexible riser VIV model test of staggered buoyancy elements. The excitation coefficient database is parameterized; and the representative parameters are systematically varied in VIVANA simulations until the predicted responses in terms of mode number, response frequency, root-mean-square (RMS) response amplitude, and RMS curvature agree well with the experimental data under same flow and boundary conditions. An optimal set of force coefficient database for both the buoyancy element and the bare riser section is obtained and a significant improvement in VIV prediction by VIVANA is achieved. The obtained hydrodynamic force coefficient database can be also applied to other empirical VIV prediction programs. The sensitivity of using the same database to predict the VIV of different configurations has also been investigated.
Highlights
Vortex-Induced Vibrations (VIV) of long flexible structures with bluff cross-sections are encountered in a great variety of physical problems, ranging from Aeolian vibrations hanging in the air to the vibrations of slender marine structures in deepwaters, e.g., cables and risers placed in ocean currents
A numerical algorithm is developed to obtain hydrodynamic force coefficient database based on the response measurements of elastic pipe VIV tests
An efficient numerical algorithm is developed to obtain the hydrodynamic force coefficient database based on response measurements of VIV tests with elastic pipes by (1) the hydrodynamic force coefficient database is parameterized; (2) these parameters are systematically scaled to create a sufficient amount of different excitation coefficient databases; (3) numerical simulations with generated databases are carried out and the optimal parameter set is selected when the predicted responses are in good agreement with the test data
Summary
Vortex-Induced Vibrations (VIV) of long flexible structures with bluff cross-sections are encountered in a great variety of physical problems, ranging from Aeolian vibrations hanging in the air to the vibrations of slender marine structures in deepwaters, e.g., cables and risers placed in ocean currents. Several model tests were carried out to investigate the interaction between VIV responses of the bare riser sections and the buoyancy elements [13,14,15]. A forced motion test of a rigid cylinder with staggered buoyancy elements was carried out to extract hydrodynamic coefficients on buoyancy elements and bare pipe sections by Wu et al [18]. A numerical algorithm is developed to obtain hydrodynamic force coefficient database based on the response measurements of elastic pipe VIV tests. Shell VIV model test ([14,16]) with staggered buoyancy elements and the optimal set of force coefficient databases for each buoyancy element and the bare riser section is obtained. The sensitivity of using the same database to predict the VIV of different configurations has been investigated
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