Input Formats |
 
|
Input Formats |
|
QTF values, current coefficients and wind coefficients are input using ASCII files. Each of these files comprise two types of lines, a data line and a comment line. The letter C (uppercase essential) in Column 1 identifies a comment line. Comment lines (which can be included at any point in the file) are completely ignored by Flexcom, and are intended to allow you to include comments for your own benefit or for other users. Any line that is not a comment line is a data line. The actual data values expected on a data line are a function of position within the file. Numerical inputs on a data line are in free format, and can be specified as floating point numbers with or without exponent. Use an uppercase E when specifying an exponent. Either commas or blanks may separate a number of values on a particular data line; do not use TABs.
The QTF data is divided into groups, with each group providing data for a particular wave frequency. Each group consists of the following lines:
1st Line: One value:
FREQ= Wave frequency (in Hz)
2nd and subsequent lines: Four values as follows:
Relative vessel/wave heading, QTFy, QTFz, QTFθ
Line 2 is repeated until QTF values are specified for all headings for this wave frequency. Then a second FREQ= line signals the start of the next group of values, and so on until values for all wave frequencies have been input. Relative vessel/wave heading in this context is defined as the angle of incidence of the wave relative to the vessel axes; refer to Vessel Heading for a more detailed definition. QTFy, QTFz and QTFθ are respectively the QTF values in surge, sway and yaw at a particular frequency.
Each line of data in a current coefficient file has the following format:
All data lines: Four values as follows:
Relative vessel/current heading, Ccy, Ccz, Ccθ
This line is repeated until current coefficient values are specified for all headings. Relative vessel/current heading in this context is defined as the angle of incidence of the current relative to the vessel axes; refer to Vessel Heading for a more detailed definition. Ccy, Ccz, and Ccθ are respectively the current coefficients in surge, sway and yaw at a particular heading.
Each line of data in a wind coefficient file has the following format:
All data lines: Four values as follows:
Relative vessel/wind heading, Cwy, Cwz, Cwθ
This line is repeated until wind coefficient values are specified for all headings. Relative vessel/wind heading in this context is defined as the angle of incidence of the wind relative to the vessel axes; refer to Vessel Heading for a more detailed definition. Cwy, Cwz, and Cwθ are respectively the wind coefficients in surge, sway and yaw at a particular heading.
QTFs and current and wind coefficients at frequencies or headings intermediate to the values you input here are found by linear interpolation. Outside of the range of frequency and/or heading values you use, a value of zero is assumed for the parameter in question.
•*QTF is used to specify Quadratic Transfer Functions (QTFs) that allow the slow drift loads on a floating body or moored vessel to be determined.
•*CURRENT COEFF is used to specify current coefficients used to determine the current loading on a floating body or moored vessel.
•*WIND COEFF is used to specify wind coefficients used to determine the wind loading on a floating body or moored vessel.
If you would like to see an example of how these keywords are used in practice, refer to D01 - Moored Vessel.