The growing confidence in the use of flexible risers for offshore production duties has encouraged designers towards the use of more ambitious geometres. The increasing range of applications have Imposed stricter requirements on the analysis software which need to be continuously updated to accommodate these new demands. Currently, many flexible user analysis packages are available which use different techniques for static and dynamic analysis using linear and non-linear methods. These are often validated through comparisons of simpler geometries with analytical solutions as well as with other programs. However, few programs have been compared with model test results or with full scale data. Comparisons with full scale data have so far been impossible due to the scarcity of such data. It has now become necessary to establish benchmark tests to compare different flexible user analysis software and to obtain an Idea of the reliability of different analysis techniques and sensitivity of their underlying formulations. This paper takes a step in this direction by reporting on the verification of a finite element based flexible user hydrodynamic analysis software named REFLEX. The package employs several non-linear static analysis methods as well as dynamic analyses using both the frequency domain and the time domain approaches. Simulations have been carried out using data from published works of numerous other investigators to provide a comparative assessment of different formulations. The verification study also uses comparisons of results of numerical analyses with both in house and independent model tests.
Static analysis of flexible risers has evolved through extension of the traditional catenary equations to allow for the effects of internal fluid weight, buoyancy and internal and external pressure forces. These equations allow computation of the static profile of a flexible riser under weight and pressure loads.