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Computational domain

The domain size for the computation is critical in determining the flow and performance. Generally, the domain is set up such that computational volume behind the ship is greater than the volume in front of it. This ensures that the domain is large enough to accommodate the pressure and velocity variations caused due to the motion of the ship.

The steps involved to define the domain under the Marine Template Mesher (Figure 8.17) are:

1. The computational domain is set up around the hull under Domain Size.It is specified using one of the dimensions of the ship/ vessel (CAD Surfaces) as the reference. The reference dimension for the computational domain is selected using the Size Reference under Domain Size. Depending on this dimension, the domain is defined on all the sides of the ship. The reference dimensions could be one of the following.
   • Each Dimension: The domain sizes are relative to the dimension of CAD Surfaces at each direction.
   • Maximum Dimension: The domain sizes are all relative to the maximum dimension of CAD Surfaces.
   • Absolute Dimension: The domain sizes are the absolute lengths in the respective directions.

Once the reference is selected the domain can be created in all directions by giving a measure of the extent of the computational domain around the hull in the following directions.

• Front: Dimension for the domain in the bow side of the vessel.
• Back: Dimension for the domain in the stern side of the vessel.
• Side: Which defines the extent for the port and the starboard side.
• Depth: Dimension for the domain in the draft region of the vessel.
• Up: Dimension for the domain in the up direction.
• Half Domain: Decides whether the domain is built for the entire vessel or one half of it. The selection can be Yes or No. If the selection is Yes, we can give a common measure for Side. If the selection is No, we define the domain in both the port and the starboard side.

Specify the Max Pitch Angle, and Max Heave .

Specify the surfaces of Hull, Deck, Up Direction, Forward Direction,and Center of Gravity.

Define the Waterline Position perpendicular to the Up Direction, relative to the Center of Gravity. (Example : If the waterline is at an absolute position of 0 m, to a vessel whose Center of Gravity is at 0,0,-1 m, the Waterline Position is defined as 1 m.)

Marine simulation domain for a displacement hull is shown in Figure 8.18 and corresponding settings are shown in the Figure 8.17)

Figure 8.17 - Domain size description

Figure 8.18 - Domain size definitions