| Title | Description |
Parameters
| TITLE | Keyword |
| Description | Up to 72 character description of the model |
The hydrodynamic surface geometry provides information related to the panel definition of the model. As with Aqwa allowance is made for symmetric models.
HYDR
length gravity
symx symy
npan
x1(1) y1(1) z1(1) x2(1) y2(1) z2(1) x3(1) y3(1) z3(1) x4(1) y4(1) z4(1)
.
.
x1(npan) y1(npan) z1(npan) x2(1) … x4(npan) y4(npan) z4(npan)
Parameters:
| HYDR | Keyword to denote start of hydrodynamic panel description |
| length | Non-dimensionalizing length unit, at this stage must be set to 1.0 |
| gravity | Acceleration of gravity in analysis units |
| symx | Set to 1 if model has symmetry about body local x axis, otherwise 0 |
| symy | Set to 1 if model has symmetry about body local y axis, otherwise 0 |
| npan | Number of panels to be defined |
| xk (j) | X coordinate for panel k, node j |
| yk (j) | Y coordinate for panel k, node j |
| zk (j) | Z coordinate for panel k, node j |
If a model contains no panel element (only Morison elements), then it is only required to specify length and gravity after the HYDR header.
The three coordinates of four nodes must always be input for each panel. Triangles are represented by allowing the coordinates of two adjacent nodes to coincide.
This defines the wave periods where hydrodynamic pressures have been computed:
PERD nperd period(1) period(2) ... period(i) period(i+1) period(i+2) ... period(nperd)
Parameters:
| PERD | Keyword to denote start of wave period data |
| period (i) | the ith wave period |
The data may be specified in one or more lines until all the periods are entered.
This defines the wave directions where hydrodynamic pressures have been computed:
DIRN ndirn heading(1) heading(2) ... heading(i) heading(i+1) heading(i+2) ... heading(ndirn)
Parameters:
| DIRN | Keyword to denote start of wave direction data |
| heading (i) | The ith wave direction (degrees) |
The data may be specified in one or more lines until all the directions are entered.
This defines the pressures at the centroids of the panels defined above in the HYDR data. Data should be given for every panel for each wave period and direction specified.
PRES Period heading region panel magnitude phase real imaginary
Parameters:
| PRES | Keyword to denote start of hydrodynamic pressure values |
| Period | Wave period |
| Heading | Wave direction (degrees) |
| Region |
Index for either quadrant or half If two planes of symmetry (symx and symy set to 1).
If one plane of symmetry (symx or symy set to 1)
|
| panel | Panel number (must be between 1 and npan) |
| magnitude | Pressure amplitude |
| phase | Associated phase angle (wrt to wave at CoG) (degrees) |
| real | Real component of pressure |
| imaginary | Imaginary component of pressure |
The HYDR, PERD and DIRN data must be defined before the PRES data.
Period and Heading must correspond to the values specified in the PERD and DIRN data.
If no input pressure is given to a panel at a particular period and direction, the pressure on this panel will be assumed to be zero. If more than one set of pressures are defined, their effects will be cumulative. The real and imaginary parts of each set will be summed together.
Data should be defined as either magnitude and phase OR real and imaginary components.
This data describes the line elements used to provide slender body loading.
MORI nmori x1(1) y1(1) z1(1) x2(1) y2(1) z2(1) . . x1(nmori) y1(nmori) z1(nmori) x2(nmori) y2(nmori) z2(nmori)
Parameters:
| MORI | Keyword to denote start of Morison hydrodynamic element description |
| nmori | Number of Morison elements defined |
| xk(j) | X coordinate for line element k, node j |
| yk(j) | Y coordinate for line element k, node j |
| zk(j) | Z coordinate for line element k, node j |
Note: A Morison element always consists of two nodes.
This data describes the element forces at the centroid of the Morison elements defined above. Loading is given as a force per unit length.
LINE period heading element realx imagx realy imagy realz imagz
Parameters:
| LINE | Keyword to denote start of Morison loading definition |
| period | Wave period |
| heading | Wave direction |
| element | Element number referencing the Morison element list |
| real [xyz] | Real component of the element global force at the Morison element centroid |
| imag [xyz] | Imaginary component of the element global force at the Morison element centroid |
The HYDR, MORI, PERD and DIRN data must be defined before the LINE data.
Period and Heading must correspond to the values specified in the PERD and DIRN data.
If no input load is given to a Morison element at a particular period and direction, the loading on this element will be assumed to be zero. If more than one set of loads are defined, their effects will be cumulative. The real and imaginary parts of each set will be summed together.
This is required in order that the acceleration loads may be computed.
MASS xcg ycg zcg mass(1,1) mass(1,2) .. mass(1,6) . . mass(6,1) mass(6,2) .. mass(6,6)
Parameters:
| MASS | Keyword to denote start of mass information |
| xcg ycg zcg | X, Y, and Z coordinate of CoG wrt to mean water level (as with Aqwa). X and Y are otherwise assumed to be in the vessel local axis set |
| mass(j,k) | Mass matrix term |