15.4. CPRF Data Record - Profiled Current Velocity

      2   5  7   11        21        31
    - --- -- ---- --------- --------- ---------
   |X|   |  |CPRF|         |         |         |
    - --- -- ---- --------- --------- ---------
       |  |   |        |       |        |
       |  |   |        |       |        |_(3) Direction of Current in Degrees(F10.0)(Default Value 0.0)
       |  |   |        |       |
       |  |   |        |       |_(2) Current Speed(F10.0)(Default Value 0.0)
       |  |   |        |
       |  |   |        |_(1) Z - Position at which the Current is Defined(F10.0)
       |  |   |
       |  |   |_Compulsory Data Record Keyword(A4)
       |  |
       |  |_Optional User Identifier(A2)
       |
       |_Compulsory END on last data record in data category(A3)

(1) The Z position at which the current is defined is with reference to the Fixed Reference Axes whose origin is at the water surface. These values will therefore always be negative and must also appear in order i.e. from the sea bed, at Z = - (Water Depth), up to the water surface at Z = 0.0.

(2) Current/Wind speed is a scalar quantity and must always be a positive value. The current components at the Z position in columns 11-20 (1) in the directions of the Fixed Reference Axes are given by

X-component = (Current Speed) * cos(Current Direction)

Y-component = (Current Speed) * sin(Current Direction)

(3) This is the direction of the current at the Z position in columns 11- 20 (1). If this field is left blank or zero is input, it will be the positive X direction of the Fixed Reference axes. As it is common to define a current profile with this value the same on all data records, the user may wish to input a single CDRN data record instead of repeating the current direction on each data record.

Note:

  • The maximum number of CPRF data records which may be used to define a current profile is 25.

  • The current profile remains constant below the lowest Z position or above the highest; it does not drop to zero outside the defined range.

  • If a wave height time-history is imported using the IWHT card it may be necessary to define the current profile with negative velocities. This is because the WHT file must contain a positive constant current in order for the waves to be calculated correctly. The total current velocity will be the sum of the value in the WHT file and the values defined here.

  • When profiled currents are used in conjunction with the CUFX, CUFY, and CURZ commands, the DPOS or DDEP data record must also be specified. If one of these data records is not specified, the current profile is ignored and a warning is issued.