The principal validation document for OrcaFlex is 99/005 OrcaFlex QA, Testing and Validation which describes the overall software QA process we use for developing OrcaFlex. The document also presents some comparisons of OrcaFlex with both real world data and other programs. We recommend that you read this document first.
Detailed validation cases
We also publish a number of more detailed validation cases:
|99/101||A comparison with Flexcom for a typical deepwater SCR. The comparison covered statics, regular
wave dynamics and irregular wave dynamics.
|99/102||A comparison with published results from a paper published at OMAE 2006. The paper compares
OrcaFlex to a code written as part of the author’s PhD study. Static and dynamic comparisons
|99/103||A comparison with published results from a paper published at OMAE 2005. The paper compares
OrcaFlex to a solution of the governing set of continuous equations for a cable with bending stiffness
for a static case.This comparison is a particularly strong validation of OrcaFlex since the authors use
the continuous equations rather than the discretised finite element approach of OrcaFlex.
|99/104||A comparison with published work by Reismann, in the International Journal of Non-Linear Mechanics.
This paper considers numerical analysis of the large-deflection due to coupled torsion/bending of a weightless
|99/105||Three separate comparisons with standard theoretical results: (1) the catenary equations, extended to allow for
axial stretch; (2) natural frequencies of a beam; (3) deflection of a cantilever beam.
|99/106||A validation of OrcaFlex’s implementation of frequency dependent added mass and damping for vessels. This compares
results from the BMT frequency domain program NMIWAVE with OrcaFlex time domain results. The comparison also provides
validation of OrcaFlex’s handling of wave load RAOs.
|99/107||A validation of the way OrcaFlex handles buoyancy forces and pipe internal contents pressure effects, and the
resulting effective tension and wall tension that OrcaFlex reports. OrcaFlex is compared against results presented
in Nigel Barltrop’s book Dynamics of Floating Structures: Volume 2.
|99/108||A comparison of statistical properties of maxima from OrcaFlex generated wave elevation time series with theoretical values
based on the Rayleigh distribution.
We have performed validation of the OrcaFlex turbine model object against documented studies available within industry. R1405#01#01 Wind Turbine Validation Report summarises the validation work, which considered the National Renewable Energy Laboratory (NREL) offshore 5-MW baseline wind turbine, recognised as an industry-standard reference turbine system. The study looks at two separate turbine systems:
- A land-based wind turbine system.
- A floating wind turbine system – based on the OC3 Hywind system.
We have been involved with several studies that compared the various OrcaFlex time domain VIV models against real-world measurements of VIV. We have documented these comparisons in the following documents:
- R648#01#02 OrcaFlex VIV Validation Summary gives an overview and summarises the three comparison studies, which are individually documented in the following three reports.
- R648#02#02 OrcaFlex VIV Comparison with Delft Model Tests reports comparisons against measurements made at model tank tests in the large flume at the Delft Hydraulics Laboratory.
- R648#03#02 OrcaFlex VIV Comparison with Schiehallion Results reports comparisons against measurements of a real full-scale drilling riser in the Schiehallion field.
- R648#04#02 OrcaFlex VIV Comparison with Deepstar Seneca Trials reports comparisons against measurements from DeepStar project experiments on Lake Seneca.
We would like to thank BP, the Norwegian Deepwater Programme, the DeepStar Project and Southampton University for access to the VIV measurements used in these comparison studies.