The CQTF data record is used to import fully coupled QTF coefficients. Both difference and sum frequency values must be input, even if the sum frequency values are not required. (Use the SQTF option (Administration and Calculation Options for the Aqwa Suite) to include sum frequencies in an analysis).

Note that import of external QTF coefficients is a "post-processing" operation that must be done after the hydrodynamic database has been created. This means that the CQTF data record will normally be used in the same run as a CPDB data record is used to import a previously calculated hydrodynamic database. It cannot be used in a full radiation/diffraction analysis, i.e. with wave frequencies and directions defined in Data Category 6.

The format of the CQTF data record is as follows.

      2   5  7   11    16    21
    - --- -- ---- ----- ----- ---------
   |X|   |  |CQTF|     |XXXXX|
    - --- -- ---- ----- ----- ---------
       |  |   |     |            |
       |  |   |     |            |_(2)File containing QTF values in AQWA format(A108)
       |  |   |     |
       |  |   |     |_(1) Structure number from which the QTF values are to be copied(I5)
       |  |   |
       |  |   |_Compulsory Data Record Keyword(A4)
       |  |
       |  |_Optional User Identifier(A2)
       |
       |_Compulsory END on Last data record in data category(A3)

(1) QTFs are copied from this structure in the QTF file to the structure number indicated by the data category keyword (DRC* data record).

(2) The format of the input file is the same as the format of the .QTF file written by Aqwa when the AQTF option is used. The .QTF file is ASCII with the first line containing the version number of the file itself and optional user title. All files must start with version 1.0 or version 2.0. A simple example using fixed format is shown here and the formatting is explained in detail below.

Version 2.0 of the AQTF format was created to accommodate the increase in maximum number of frequencies from 50 to 100.

AQTF-2.0 :Example - Fully-Coupled SUMM/DIFF QTF
  1  4   3          0.00000    30.00000    45.00000    90.00000
                  0.3490659   0.4188791   0.5235988
  1  4   2   3  -1.4695E-03  4.8995E+05 -7.4829E+03 -1.0434E+07  2.9763E-01 -2.1092E+04
                -5.0714E-03  3.1427E+03 -2.0972E+03 -3.4310E+04  5.3036E-02 -2.4030E-01
                 1.3916E-01  1.1357E+06  1.2190E+03 -8.1649E+06  6.3355E-01 -1.9725E+04
                 1.0582E-01  7.0678E+05  1.2178E+03 -4.6883E+06  1.0078E+00 -7.8328E+03

The format descriptions below make use of FORTRAN style codes. The meaning of these is:

AQTF-1.0 or AQTF-2.0: User title

A FREE_FORMAT keyword may be input if free format is required. Free format will allow the user to input the data in any columns as long as the correct number of data items is input.

Then for each structure:

(Str no.) (No. of Directions) (No. of Frequencies) (Direction values)

(a) V1.0: the fixed format is (3I2,2X,6F12.4)

(b) V2.0: the fixed format is (2I3,I4,5X,6F12.4)

If there are more than 6 directions, the remaining directions are input in blocks of 6.

(a) V1.0: the fixed format is (8X,6F12.4)

(b) V2.0: the fixed format is (15X,6F12.4)

The frequencies are then input in blocks of 6

(a) V1.0: the fixed format is (8X,6F12.4)

(b) V2.0: the fixed format is (15X,6F12.7)

The QTF data is then input as follows:

(a) V1.0: the fixed format is (4I2,6E12.4), then (8X,6E12.4)

(b) V2.0: the fixed format is (2I3,2I4,1X,6E12.4), then (15X,6E12.4)

(Str no.) (Dirn no.) (Freq#1) (Freq#2) (6* REAL Difference frequency QTF values)

(6* IMAG Difference frequency QTF values)

(6* REAL Sum frequency QTF values)

(6* IMAG Sum frequency QTF values)

This is then repeated until all the frequencies/directions have been input for this structure, a total of (No. of Directions)*(No. of Frequencies)*(No. of Frequencies) logical records.

QTF values for another structure may then follow.