Conductance data
The thermal solver model consists of a set of elements connected by a network of conductances. This section discusses querying and manipulating conductance values. The conductance attributes are listed in the following table:
| Attribute | Access | Description |
|---|---|---|
| Conductance number | Implicit Use subroutine |
A unique label for each conductance, assigned by TMG. |
| Elements | Use subroutine TMGN12 |
The internal labels of the elements that the conductor joins. Generally the order is of no significance, one-way conductances are an obvious exception. |
| Conductance type | Use subroutine TMGN12 |
An integer value representing the conductance type, the values are interpreted as shown in the conductance types table. |
| Conductance Parameter | Array R(j) |
Is the conductance parameter used to calculate GG at every iteration. The value is stored as a resistance, that is 1/conductance. |
| Conductance Value | Array GG(j) |
The current value of the resistance, that is the reciprocal of the conductance value. |
The conductance types are listed in the following table:
| Type Value | Type | Stored in R(j) |
|---|---|---|
| 0 | Linear (conductive) conductance |
1/Conductance
|
| 1 | Radiative conductance | area*emissivity*graybodyview factor* Stephan-Boltzmann's
constant |
| 2 | Follower conductance | A value of 1.0E36 |
| 3 | Fluid element forced or free convection conductance |
1 / Projected area * h
|
| 4 | Free convection conductance |
1 / Projected area * h
|
| 5 | Fluid flow resistance | Flow resistance multiplier/length |
| 6 | One way radiative conductance | area*emissivity*graybodyview factor* Stephan-Boltzmann's
constant |
| 7 | One way conductance |
1 / (Massflow*Cp)
|
The best way to access conductances is using the subroutine TCNAME. This
routine can:
- Create a list of conductances between two named groups of elements.
- Create a list of conductances from a named group of elements to the rest of the model
The only value associated with a conductance that can be modified is the conductance value. A conductance cannot be deleted directly but it can be effectively eliminated by setting its value to a very low quantity at every iteration. You cannot directly change the elements associated with a conductance or its type. If you wish to do either of these you must:
- Create a new conductance with the characteristics you require. For more information, see Add conductances.
- Effectively delete the original using the method described above.
- Repeat step 2 at every iteration.
When changing a conductance value you must change the values in the array
GG.