The first step is creating the surfaces defining the hull. These will be created using the batch file used in the previous example. Once the hull geometry has been created, we can start the Tdyn wizard and follow its instructions.
As said before, Tdyn wizard can be started through the menu option Utilities>Tdyn Wizard>Tdyn Wizard.
The first step of the Tdyn wizard will automatically open the Layers window and indicate us to split the geometry in different layers. Fortunately, most of this work has been automatically done while creating the geometry and we have only to move to the symm_oy layer those lines of the hull belonging to the symmetry plane and being below the floating line. This can be easily done by means of the Send To option of the Layers window.
A summary of the contents of every layer is shown next:
Layer | Entities |
body_wet | Surface 2 |
body_dry | Lines 1, 4, 5, Surface 1 |
free_surf | Line 3 |
symm_oy | Lines 12, 13, 14 |
Figure 66. Entities to be splitted in the Tdyn wizard layers |
Once the first step of the Tdyn wizard is ready we can proceed to the next step by pressing Next button in the Wizard window.
Now, Tdyn wizard will open the Control volume window (see Figure 67). This window allows an easy definition and creation of the control volume for our case. In order to do it, the dimensions of the volume have to be defined. In our case next values have to be defined:
X factor Fore = 0.7, X factor Aft = 1.4 (define the x-length of the control volume).
Y factor = 0.8 (defines the y-length of the control volume).
Z factor = 0.7 (defines the z-length of the control volume).
We have also to insert the extreme aft and fore points (as defined in the previous example) of the floating line. These are the points 5 (fore extreme) and 6 (aft extreme) of Figure 66.
Finally, we have to press OK to create the control volume. Then, press Next button in the Wizard window to go to the next step.
Figure 67. Tdyn wizard. Create control volume window |
Now Tdyn wizard opens the Define Data window. This window allows a comfortably definition of the basic data for the analysis in most cases.
We have to set the values in this window as shown in Figure 68.
Note that you can also manually modify the boundary conditions, materials and boundaries definitions and continue the process.
Figure 68. Tdyn wizard. Define data window |
By pressing OK button, the following actions are automatically carried out:
We can now modify manually the boundary conditions assignment, and materials and boundaries definition. This is not necessary if the default values are correct, but in our case we will make some modifications to run the problem with the same characteristics defined in the previous example. In order to do this, please change the PROBLEM definition (General tag) accordingly to Figure 55 and the Auto Body data accordingly to the Fluid Body definition shown in Figure 52.
Once the data definition is completed, press Next button in the Tdyn window to continue with mesh generation.
Tdyn wizard's Generate mesh window allows an easy definition of element sizes and mesh characteristics for the analysis in the most common cases.
The following commands are available in the Generate mesh window:
Layer Body_wet size: Average size for unstructured elements in the Body_wet layer. If a negative value is given, this input is ignored.
Layer Free_surf size: Average size for unstructured elements in the Free_surf layer. If a negative value is given, this input is ignored.
General size: Average size for unstructured elements, which will be applied to the rest of lines, surfaces and volumes that do not have a previously defined element size.
Mesh size factor: Mesh size factor controls whether the mesh is coarser or finer, based on standard criteria. A greater Mesh size factor generates a coarser mesh.
Unstructured size transitions: It controls whether the transitions between different element sizes are slow or fast.
OK: The mesh will be generated. Note that this may take some
In this example (see Figure 69) the mesh size of the free surface (Layer Free_surf size) has to be set to 0.1 and the hull (Layer Body_wet size) to 0.05. The elements General size has been fixed to 1.0 and the Unstructured size transitions has been set to 0.5. This way we will obtain the same mesh as in the previous example.
Figure 69. Tdyn wizard. Generate mesh window |
Once the mesh has been generated, press Next to continue with the problem calculation.
If all the previous steps have been successfully completed, the problem is ready to be calculated (solution process). This can be done by means of the Process window. Just press Start to launch the process.
Information about the progress of the solution can be displayed by pressing the Output View button. It is also possible to draw a graph of the forces evolution on the body.
Note that you can also perform the commands using the standard buttons in the Tdyn Toolbar.
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Calculate | Output View | Kill a process | Draw Forces on Bodies icons |
When the Tdyn calculation process is finished, the system displays the following message:
“Process …-name-… started on …-date-… has finished.” Then, press the Next button to go to the post-processing part.
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