Fluid Volume Properties
Description: Defines the properties of an incompressible fluid volume for the purpose of generating a virtual mass matrix.
Format:
Example:
| Field | Definition | Type | Default |
|---|---|---|---|
| SID | Set identification number. | Integer > 0 | Required |
| CID | Identification number of rectangular coordinate system used to specify the orientation of the free surface (normal to the coordinate z-axis). | Integer ≥ 0 or blank | |
| ZFS | Intercept of the free surface on the z-axis of the coordinate system referenced by CID. See Remark 4. | Real | ∞ |
| RHO | Fluid density. | Real | Required |
| ELIST1 | Identification number of an ELIST entry that lists the identification numbers of two-dimensional elements that can be wetted on one side by the fluid. Only those elements connected to at least one grid point below ZFS included. See Remarks 3, 4, and 5. | Integer ≥ 0 or blank | Required if ELIST2 is blank |
| ELIST2 | Identification number of an ELIST entry that lists the identification numbers of two-dimensional elements that can be wetted on both sides by the fluid. Only those elements connected to at least one grid point below ZFS included. See Remarks 3, 4, and 5. | Integer ≥ 0 or blank | Required if ELIST1 is blank |
| RMAX | Maximum element interaction distance. Interactions between elements with distance that is greater than RMAX will be ignored. | Real > 0.0 | 1.0E+10 |
Remarks:
- The MFLUID entry must be selected with the Case Control command MFLUID = SID.
- Several MFLUID entries corresponding to different fluid volumes can be used simultaneously.
- The wetted side of an element in ELIST1 is determined by the presence or minus sign preceding the element ID on the ELIST entry. A minus sign indicates that the fluid is on the side opposite to the element's positive normal, as determined by applying the right-hand rule to the sequence of its corner points. The same element can appear on two ELIST entries, indicating that it forms a barrier between the unconnected fluids.
- The fluid volume may be finite (interior) or infinite (exterior) and may be bounded by an optional free surface defined by ZFS. The default free surface is located at an infinitely large positive ZFS value.
- The ELIST entry may only reference CQUAD4/CQUADR and CTRIA3/CTRIAR elements.
- The handling of special cases where adjacent element surfaces normals are more than 30 degrees from each other such as a corner is controlled using PARAM, VFMNORMTOL (see Section 5, Parameters, for more information on VFMNORMTOL).
- PARAM, VFMADDMETHOD controls where in the solution sequence the virtual fluid mass is included in the global mass matrix (see Section 5, Parameters, for more information on VFMADDMETHOD).