tdynwizard manual


Update Sink and Trim Data

Sink & Trim wizard automatically updates the free surface, and sink and trim of a geometry (hull), based on a previous calculation (it is necessary to perform an initial analysis before using this wizard). We advise to use Tdyn wizard to perform the initial calculation.

This wizard easily updates the geometry, generates the control volume around a body (hull), assigns the main data, and generates a mesh to finally perform the simulation. Moreover, Sink & Trim wizard will also help you in the post-processing and reporting of the results.

Sink & Trim Wizard can be accessed through the menu option Utilities>Tdyn Wizard>Sink&Trim Wizard.

Sink & Trim wizard can be used for the following types of problems:

Case 1. Semi-submerged floating body with free surface. Geometry and boundary conditions with symmetry in y=yo plane. Main flow in +x or -x direction.

Case 2. Semi-submerged floating body with free surface. Geometry and boundary conditions without symmetry. Main flow in +x or -x direction.

Figure 13 Sink and Trim Wizard cases

Sink & Trim wizard is based on the layers splitting used in the Tdyn wizard. Before you start, we advise to import the body (bodies) geometry and split it to the following layers:

1.      Layer called body_wet with all the surfaces of the body.

2.      Layer the called symm_oy with the lines of the body (if any) belonging to the symmetry plane (this symmetry plane must be of type y = yo). This layer will only be used in case 1 (see above).

Layers window can be accessed through the menu option Utilities>Layers.

It is also possible to read the above data from the previous geometry definition, but since the free surface will be updated, the quality of the resulting geometry may be worse than reading the original geometry.

A control volume generation using the Sink & Trim wizard may be performed by using the Read previous data window.

The following commands are available in the Read previous data window:

File: GiD file containing the previous calculation data.

Read hull geometry: If this option is selected, hull geometry of the previous calculation will be read and used.

Read free surface: If this option is selected, free surface obtained in the previous calculation will be read and used.

Sinkage: Sinkage to be applied. It is defined as the displacement in the Z axis. It is read from the previous calculation, but may be modified at any time.

Trim angle: Trim angle to be applied. It is defined as the rotation around Y-axis passing by the center of gravity. It is read from the previous calculation, but may be modified at any time.

Apply: Sink and trim, and free surface update is applied.

OK: Control volume is generated.

Figure 14 Read previous data window

 

After pressing Apply button, the following actions will be performed:

  1. Read hull geometry (if selected).
  2. Read updated free surface (if selected) obtained from previous calculation.
  3. Apply sink and trim data to the hull geometry.
  4. Calculate hull-free surface intersection.
  5. Split the resulting geometry in different layers.

Above actions may take several minutes.

Due to the huge variety of possible problems, the Apply button may not work correctly in all cases. In case of an error it is possible to manually carry out these actions and continue normally.

After pressing OK button, the control volume will be generated.

Once you have finished, press Next> button in the Wizard window to go to the next step.