A circular disc element with no thickness and no mass. The DISC element has a drag coefficient and added mass coefficient in its normal direction. To add mass, the user can define a PMAS element and attach it to the DISC element.

The DISC element has two nodes; the first defines the center of the element and the second gives the normal direction of the element.

The force on a DISC element has two components: added mass force and drag force. As DISC elements have no thickness, the Froude-Krylov force and hydrostatic force are zero. This is different from a TUBE end on which the Froude-Krylov force and hydrostatic force are non-zero and therefore are calculated in Aqwa. The application point of the force is at the centroid of the DISC element when fully submerged, and at the force center computed by the program if partially submerged. The direction of the force on a DISC is parallel to the normal direction of the DISC.

DISC elements in Aqwa are single sided; for example, they are assumed to be adjacent to the end of a TUBE. The added mass and drag forces are based on this assumption, and are simply one-half the forces for a stand-alone disc. If the intention is to model a DISC by itself (for example, a heave plate on a TLP) the added mass and drag coefficients should be doubled.