*ENVCURRENT

Data format:

One line with 3 parameters, as follows:

S_CURR_VIV RAP_VIV_BOTT FILENAME

Purpose:

This keyword defines a list of current profiles to be considered and performing series of VIV analyses with the DEEPVIV module within a single simulation. The combined VIV fatigue damage induced by the different current profiles is provided upon completion of the simulation.

Status:

Optional.

Details :

Parameter	Description
S_CURR_VIV	The curved abscissa along the line for which specific outputs are to be reported for every current profiles. The curved abscissa exhibiting the largest damage rate should typically be used. Defaults to 0. If S_CURR_VIV < 0, the specific outputs are automatically reported at the location of the maximum damage along the line. The specific outputs that are reported in the DAY and LIS files when the simulation completes are as follows: Current Identification Number Current Occurrence Probability (%) Maximum Damage Rate (1/year) Curved Abscissa along Line Section Point (denotes the position over the circumference through values from 1 to 8) Largest Modal Power (Watt) Mode Identification Number yielding the Largest Modal Power Associated Frequency (Hz) Largest Modal Amplitude (m) Mode Identification Number yielding the Largest Modal Amplitude Associated Frequency (Hz)
RAP_VIV_BOTT	When the last velocity of the current profile is a wrong value, it is extrapolated from the last but one level velocity (see note). Defaults to 0. Note: Values of currents of 99.9 m/s are considered as wrong values and a specific treatment is performed : If the wrong value(s) can be bracketed by two valid velocities, an linear interpolation is conducted. The same interpolation is done for direction. If the velocity value is wrong at the last depth, it is then extrapolated from the preceding depth level using the ratio rap_VIV_bott : U(bottom) = RAP_VIV_BOTT U(last but one level)
FILENAME	Path and filename for the external data file listing the current profiles. The format of the external data file is as follows: List of Z positions at which the current velocities and directions are provided. This Line must always start with "DEPTH=" followed by the list of Z-position values (negative values are below the sea level). Comments area (optional): The maximum number of rows for comments is 40. End of comments line (compulsory): This line indicate the end of the comment areas. It must always be composed of "-" characters. The line must include 11 "-" characters as a minimum. Current Data Lines: The number of current data lines equals the number of current profiles to be considered. Each current data line is composed as follows: One blank space (compulsory) Current Name (followed by a least one blank space): The maximum number of characters is 19. Velocity & Direction Values (separated by blank spaces, and followed by one blank space at least): (Velocity, Direction) must be provided for every Z-position listed in the first line of the file (Velocity in m/s and direction is degrees with respect to the global X-axis). Occurrence percentage (%): If not specified, all the currents are given the same probability (100/Number of Currents). For instance, a probability of 50% must be set as 50.0 in the input file. Also see the data file example shown below for details.

Warning

The cumulated results in terms of fatigue are gathered in the file ANALYSISNAMEVIVdamage_section.txt for the DeepLines input file ANALYSISNAME.LOG.

The results displayed by the GUI in the DSS file are associated to the last current profile only.

External data file example:

  DEPTH = 0.00 -37.00 -65.00 -97.00 -500.00 -800.00 -1000.00 -1150.00 -1600.00 -1700.00
  ――――――――
  Current1 0.15 0. 0.15 0. 0.17 0. 0.15 0. 0.08 0. 0.10 0. 0.12 0. 0.10 0. 0.10 1. 0.05 0. 10.00
  Current2 0.12 0. 0.10 0. 0.14 0. 0.14 0. 0.07 0. 0.09 0. 0.09 0. 0.08 0. 0.08 0. 0.05 0. 18.00
  Current3 0.07 0. 0.07 0. 0.12 0. 0.12 0. 0.05 0. 0.09 0. 0.09 0. 0.07 0. 0.07 0. 0.05 0. 20.00
  Current4 0.07 0. 0.07 0. 0.09 0. 0.07 0. 0.04 0. 0.05 0. 0.06 0. 0.05 0. 0.05 0. 0.02 0. 22.00
  Current5 0.03 0. 0.03 0. 0.06 0. 0.06 0. 0.03 0. 0.04 0. 0.05 0. 0.03 0. 0.03 1. 0.02 0. 30.00