OrcaFlex |
 
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OrcaFlex |
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OrcaFlex models can be saved in either binary data files (.dat) or text data files (.yml). Flexcom can import RAO data from an OrcaFlex text data file (.yml) only. The conventions used in Orcaflex are as follows:
•The definition of wave heading is transformed such that a 0 degree heading, which is incident on the stern in the OrcaFlex format, is incident on the bow in the Flexcom format.
•All other formats are set on a file by file basis and the interpretation of the available options in OrcaFlex are as follows:
•RAOResponseUnits: it is assumed that this refers to the units in which the rotational RAOs are referred to in the yml file. If they are stated as being in “radians” then Flexcom multiplies these rotational RAOs by (180/pi). If they are stated as being in “degrees” then no conversion will take place.
•RAOWaveUnit: It is assumed that this is always set to “amplitude” and if not Flexcom produces an error. No conversion will take place based on this convention but Flexcom will produce an error if either “max wave slope” or “wave steepness” is the stated convention.
•WavesReferredToBy: It is assumed that this option is a statement of what the units of wave period are for the RAOS in the yml file. Flexcom converts the values referenced by this convention from the convention stated in the yml file to the Flexcom format. If the waves are referred to in “periods” then Flexcom performs the following conversion (1/period). If the waves are referred to in “frequency (rads/s)” then Flexcom divides them by (2*pi). If the waves are referred to in “frequency (Hz)” then no conversion will take place.
•RAOPhaseConvention: It is assumed that this refers to the positive rao phase angle of the RAOs in the yml file. If the option in OrcaFlex states that the phase angle “leads” then Flexcom will multiply all the phase angles by -1. Otherwise if the option states that it “lags” Flexcom will not perform any conversion.
•RAOPhaseUnitsConvention: It is assumed this refers to the units that the phases in the yml file are in. If the phases are stated as being in “radians” then Flexcom multiplies the phases by (180/pi). If the phases are stated as being in “degrees” then Flexcom will not perform any conversion.
•RAOPhaseRelativeToConvention: It is assumed that this refers to the positive wave elevation. If the phases are stated as being relative to the “trough” then Flexcom subtracts 180 from all of the phases. If the phases are stated as being relative to the “crest” then Flexcom does not perform any conversion. If the phases are stated as being relative to either the “zero up-crossing” or “zero down-crossing” then Flexcom does not continue with the analysis and produces an error.
•SurgePositive: It is assumed that this refers to the positive surge direction. If the positive surge direction is stated as being “aft” then Flexcom converts the surge phase by subtracting 180 from it. If the positive surge direction is stated as being “forward” then Flexcom will not perform any conversion.
•SwayPositive: It is assumed that this refers to the positive sway direction. If the positive sway direction is stated as being “starboard” then Flexcom converts the sway phase by subtracting 180 from it. If the positive sway direction is stated as being “port” then Flexcom will not perform any conversion.
•HeavePositive: It is assumed that this refers to the positive heave direction. If the positive heave direction is stated as being “down” then Flexcom converts the heave phase by subtracting 180 from it. If the positive heave direction is stated as being “up” then Flexcom will not perform any conversion.
•RollPositiveStarboard: It is assumed that this refers to the positive roll direction. If the positive roll direction is stated as being starboard “up” then Flexcom subtracts 180 degrees from the roll phases. If the positive roll direction is stated as being starboard “down” then Flexcom will not perform any conversion.
•PitchPositiveBow: It is assumed that this refers to the positive pitch direction. If the positive pitch direction is stated as being bow “up” then Flexcom subtracts 180 degrees from the pitch phases. If the positive roll direction is stated as being bow “down” then Flexcom will not perform any conversion.
•YawPositiveBow: It is assumed that this refers to the positive yaw direction. If the positive yaw direction is stated as being bow to “starboard” then Flexcom subtracts 180 degrees from the pitch phases. If the positive yaw direction is stated as being bow to “port” then Flexcom will not perform any conversion.
•Symmetry: It is assumed that this refers to the planes in which the stated RAOs are set to be mirrored. If the mirroring option is stated as being in the “XZ plane” then Flexcom will mirror the RAOs about the surge axis. If the mirroring option is stated as being in the “YZ plane” then Flexcom will mirror the RAOs about the sway axis. If the mirroring option is stated as being in the “XZ and YZ plane” then Flexcom will mirror the RAOs about the surge and sway axes.
•The reference units of the rotational RAOs (i.e. whether the angle is specified per metre or per foot) may be adjusted if the OrcaFlex units differ from the Flexcom units. Typically the OrcaFlex units are ascertained automatically from the external file, but as this is not always possible, you are advised to explicitly state the unit system (along with the file name) in order to avoid any possible ambiguity.