Pressure Post-Processing

The commands discussed in this section deal with the frequency response of the pressure on a panel. As mentioned previously, the data for these commands depends on the manner in which the original frequency response data was computed. If it was computed with an RAO command, then all options and data discussed here are available. If it was computed with an SRESPONSE command, then no environmental data can be specified.

To obtain the frequency response of the average pressure over a panel, issue the command:

     FR_PANPRESS, :PAN_SEL   -OPTIONS

Here, :PAN_SEL is a selector for the panels you want pressure on, and the only available option is -FILE. If one uses this option, the pressures on panels selected by :PAN_SEL will be written to the ppo file, and the Disposition Menu will not be entered. Alternatively, if the option is not used, :PAN_SEL should select only a single panel, and the user is placed in the Disposition Menu to dispose of the results as desired.

To compute statistics of pressures in irregular seas, one should issue:

     ST_PANPRESS, :PAN_SEL, ENV_NAME, -OPTIONS

where the available options are:

     -SEA, SEA_NAME, THET, HS, PERIOD, GAMMA

     -SP_TYPE, TYPE

     -SPREAD, EXP

     -E_PERIOD, EP(1), EP(2), .....

     -CSTEEP,  YES/NO

The options -SEA, -SP_TYPE, and -SPREAD are used to define the seastate to which the vessel will be subjected and are the same as if they were specified on an &ENV command. The -E_PERIOD option can be used to generate results for seas of several different periods. If this option is omitted, then a single period of PERIOD will be considered. With the option, periods of PERIOD, EP(1), EP(2), ... will be produced. The statistical result is the statistic specified with the last -PROBABILITY option on a &DEFAULT command. As with the &ENV command, the meaning of PERIOD and PER_INC depend on either the setting of TYPE specified with the -SP_TYPE option or with -SP_TYPE specified on if they were specified on an &ENV command. If the original response data was produced with the SRESPONSE command, then no additional data can be specified. If -CSTEEP is specified with a YES/NO of YES, then the height of the wave will be altered so that all seastates have the same steepness as the initial one. Otherwise, the wave height will remain constant.

Here, the statistic of the pressure on panels selected by :PAN_SEL will be returned and the user will be placed in the Disposition Menu. Here, there is no limit on the number of panels selected.