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All objects data form |
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All objects data form |
The all objects data form allows you to view and edit data for all the objects in the model on a single form. This is particularly useful for simultaneous viewing or editing of properties of multiple objects: for instance, you can move the initial positions of some or all of the objects by a fixed amount in a single operation. The form can be opened from the model browser.
The form has three modes of presentation, showing either connections, characteristic scales or other data.
The connections mode presents connection-specific data. The included objects choices allow you to filter which object types appear in the list – each object type (lines, winches, links, etc.) may be included in or excluded from the list. The group by choice affects the ordering of the objects in the list wihch have multiple connections: for example, grouping by object will group together in the list end A, end B, and any mid-line connections for each line in turn, whereas grouping by connection will group together the end A connections for all lines, end B connections for all lines, and midline connections for all lines.
The positions page contains the position data for each connection in the model. These are the same data as on the individual object data forms, presented here collectively, and are:
| Note: | Different objects use different Euler angle conventions for their orientations. So the columns in this table are labelled generically, orientation angle 1, 2 and 3. An extra informational column is provided which states the Euler angle convention that is used to interpret the data, e.g. azimuth, declination gamma; heel, trim, heading; rotation 1, 2, 3; etc. |
The polar coordinates page provides a way of viewing or setting the positions of the connections using polar coordinates, relative to a choice of frames of reference. This facility is particularly useful for cases (e.g. mooring arrays) where a series of connections need to be laid out around a circle.
The polar coordinates R, theta $(\theta)$, Z are those of the connection position relative to the selected frame of reference (see below). The Cartesian coordinates of the connection, relative to the same reference frame, are $(R\cos\theta, R\sin\theta, Z)$. These are not necessarily the same as the Cartesian object-relative position coordinates, which are relative to the frame of reference of the parent object.
OrcaFlex keeps these two sets of coordinates synchronised, so if you change one then the other is automatically updated to match. If you change any other data then the Cartesian object-relative position coordinates are considered to be the primary source of data and left unchanged, and the polar coordinates are updated accordingly.
You have a quite a lot of flexibility to choose the reference frame you want for the polar coordinates. The reference frame has its origin at your chosen reference origin and its axes aligned with your chosen reference axes.
For the reference origin you can choose from:
And for the reference axes directions you can choose between:
The choices of reference frame for the polar coordinates may seem complex at first sight, but they allow various useful coordinate transformations to be performed easily and accurately. Consider mooring a spar with an array of four lines, each of which has end A connected to the spar and end B anchored.
Firstly, suppose you want to place the A ends of the lines so that they are evenly spaced circumferentially around the spar, all at radius 5m from the spar axis and all 3m below the spar origin. To do this easily, group by connection, so that all the ends A are grouped together. Then, for the first line, set the reference frame origin and axes to be the spar origin and spar axes and set its polar coordinates to $R{=}5, Z{=}{-}3$; copy/paste or fill down to assign the remaining A ends to the same reference origin, axes and $R$ and $Z$ coordinates. Finally, set the $\theta$ coordinates for the A ends to 0°, 90°, 180° and 270°.
Now suppose you want the B ends to be anchored to the seabed, again evenly spaced circumferentially, and with each line spanning 200m horizontally. The easiest way to implement this is to have the reference origin at end A (the other end, for each line) and the reference axes the spar axes. The $\theta$ coordinates should again be 0°, 90°, 180° and 270°; $R$ is now 200m. In this case, the vertical positions of the B ends are most easily assigned by setting connect to object to be anchored on the connections page and then the position $z$ coordinate to zero on the positions page.
The connections page has details of the nature of the connection itself:
OrcaFlex objects with free DOFs (e.g. buoys, line nodes, calculated vessels) generally have instrinsic properties, such as their size or mass, which can be used as characteristic scales for convergence checks by the iterative solvers employed within OrcaFlex. However, it is sometimes useful to be able to set these scales manually. This page of the all objects data form allows you to set characteristic length, $\vec{l}_\textrm{char}$, and characteristic force, $\vec{f}_\textrm{char}$, values explicitly for each object in the model that can have free DOFs (the included objects choices allow you to filter which object types appear in the list). The default value of ~ for the characteristic length or force instructs OrcaFlex to compute that property automatically via a consideration of the typical lengths and forces (e.g. weight and buoyancy) that act within each group of coupled objects in the model. Sometimes, if the coupled objects within a group have no weight or buoyancy, this calculation can result in an answer of zero for the characteristic length/force. An error message will be raised if this happens; it may then be necessary to set the characteristic scales manually. OrcaFlex may also require characteristic moment, $\vec{m}_\textrm{char}$, values during an analysis. These are used as a measure of convergence for rotational degrees of freedom (i.e. angles). If neither the characteristic length nor the characteristic force have been set to '~', then the characteristic moment values will be estimated as the product of the two; otherwise, OrcaFlex will estimate the characteristic moment based on the intrinsic properties of each group of coupled model objects.
The characteristic force and moment determine the accuracy of the analysis for the degrees of freedom of that model object. Broadly speaking, the force accuracy is given by $\textit{tol} \times |\vec{f}_\textrm{char}|$ and the moment accuracy by $\textit{tol} \times |\vec{m}_\textrm{char}|$, where $\textit{tol}$ is a tolerance (e.g. the whole system statics tolerance or the implicit integration tolerance) associated with some aspect of the analysis. The force accuracy applies to translational degrees of freedom (positions); the moment accuracy applies to rotational ones (angles).
The other data mode presents tables of data for all the various OrcaFlex model objects. Collectively, these tables contain the same data as are presented on the individual object data forms. The tables are, however, laid out with each row containing related data for (usually) a single object, and different classes of data on separate pages.
This tabulation allows data for multiple objects to be set in an efficient and coordinated way. The copy/paste or fill down keyboard shortcuts are particularly helpful here. Another useful technique is to build a table of data in Excel with an identical layout of rows and columns. This allows you to make use of Excel's formulae and data handling facilities to prepare data, and then to paste it into OrcaFlex in a single operation.