Spherical Coordinate System Definition, Form 2
Description: Defines a spherical coordinate system by reference to the coordinates of three points.
Format:
Example:
| Field | Definition | Type | Default |
|---|---|---|---|
| CID | Coordinate system identification number. | Integer > 0 | Required |
| RID | Identification number of a coordinate system that is defined independently from this coordinate system. | Integer ≥ 0 | 0 |
| Ai, Bi, Ci | Coordinates of three points in coordinate system defined in field 3. | Real | Required |
Remarks:
- Continuation entry must be present.
- The three points (A1, A2, A3), (B1, B2, B3), (C1, C2, C3) must be unique and noncollinear. The model translator checks for noncollinearity.
- Coordinate system identification numbers on all CORD1C, CORD1R, CORD1S, CORD2C, CORD2R, and CORD2S entries must all be unique.
- The reference coordinate system must be independently defined.
- A RID of zero (or blank) references the basic coordinate system.
- The location of a grid point (P in the sketch) in this coordinate system is given by (R, θ, ɸ) where θ and ɸ are measured in degrees.
- The displacement coordinate directions at P are dependent on the location of P as shown below by (
,
,
).
- Points on the z-axis may not have their displacement directions defined in this coordinate system since ambiguity results. In this case the basic rectangular system will be used.
Figure 1. CORD2S Definition