Disc elements can be used to create an area that has drag and added mass in the direction perpendicular to the disc.
To add a Disc element:
Select a Part in the tree view.
Right-click the Part and select Add > Disc, or click the Disc icon in the Parts toolbar.
Select the Disc object in the tree and set the properties.
The Diameter of the disc is required along with the centroid and the definition of the normal direction. If the centroid is at the position of an existing vertex, set Centroid Definition to Select Vertex and click Pick in the Vertex field; then select the vertex on the model and click . To enter the coordinates of the vertex directly, set Centroid Definition to Specify Coordinates, and enter the X, Y, and Z values.
You can specify the normal by picking a second vertex or specifying the direction of a normal vector. To use an existing vertex to define the normal, set Normal Definition to Select Second Vertex and click Pick in the Normal Vertex field; then select the vertex on the model and click Apply. To enter the vector for the normal directly, set Normal Definition to Specify Vector Components, and enter the Normal X, Normal Y, and Normal Z component values.
The default values of the added mass (Added Mass Coefficient) and viscous drag coefficients (Drag Coefficient) can be modified if desired. See Properties of Typical Morison Elements in the Aqwa Theory Manual to see how these coefficients are used in the program.
Note: Drag is not used in Hydrodynamic Diffraction or Frequency Statistical Analyses unless the Linearized Morison Drag option is used from the Common Analysis Options.