11.5.3. The WAMS/WDMP Data Record - Wave Frequency Added Mass Matrix and Wave Frequency Damping Matrix

These data records may be used to input the added mass matrix (WAMS) and linear damping matrix (WDMP) at the frequency/period specified on the preceding FREQ/PERD/HRTZ data record. If the matrix has been read from backing file, the WAMS or WDMP data record will replace (i.e. overwrite) the existing values within that matrix. (NB see Note 1 at the end of this section, when using Aqwa-Line.)


      2   5  7   11    16    21        31        41
    - --- -- ---- ----- ----- --------- --------- ------
   |X|   |  |WAMS|     |     |         |         |      ...
    - --- -- ---- ----- ----- --------- --------- ------
   |X|   |  |WDMP|     |     |         |         |      ...
    - --- -- ---- ----- ----- --------- --------- ------
       |  |   |     |     |       |         |         |
       |  |   |     |     |       |----------------------
       |  |   |     |     |       |
       |  |   |     |     |       |_(4) 6 Mass/Inertia or Linear Damping Values(6E10.0)
       |  |   |     |     |
       |  |   |     |     |_(3) Row Number of Added Mass or Damping Matrix(I5)
       |  |   |     |
       |  |   |     |_(2)  Structure Number(I5)
       |  |   |
       |  |   |_(1) Compulsory Data Record Keyword(A4)
       |  |
       |  |_Optional User Identifier(A2)
       |
       |_Compulsory END on last data record in data category(A3)

(1) This data record keyword indicates whether the values (4) refer to the added mass (WAMS) or damping matrix (WDMP).

(2) If the analysis includes hydrodynamically interacting structures, this is the number of the structure which interacts with that defined on the data category keyword (WFS*). The structure must be input even if the coefficients are those giving the effect of the structure on itself (i.e. structure 1 in data category WFS1). Both complete added mass and damping matrices should be input; if part matrices are input the results will likely be inaccurate, or the program may fail. When using Aqwa-Line, see the note 1 below.

(3) This number indicates to which row of the added mass/damping matrix the values in columns 21-80 correspond.

(4) These are the values which REPLACE those in row (3) of the existing added mass/damping matrix.

Note:

  1. Effect of the WAMS/WDMP Data Record when Running Aqwa-Line

    Input of the added mass/damping matrix is redundant information when running Aqwa-Line, as the program normally calculates these matrices. Therefore, use of one or more WAMS/WDMP data records will instruct Aqwa-Line not to perform a radiation/diffraction analysis at this frequency. You must then import or specify all other parameters which would otherwise be calculated at this frequency; in other words, the linear damping/added mass matrix, Froude Krylov and diffraction forces.

  2. These data records are not valid for a structure with forward speed in multiple wave directions.