When you create a table, you must define its independent and dependent variables. You can identify which variables correspond to each column of data when you load a table from an external data file. Alternatively, you can manually specify the independent and dependent variables in tables that you enter or edit in the tables function.
Independent Variables
A table must contain one or more independent variables (or primary variables), which represent independent, measurable quantities. The Mechanical application supports the following types of independent variables.
X Coordinate
Y Coordinate (Cartesian coordinate systems)
Theta Coordinate (Cylindrical coordinate systems)
Z Coordinate
Time
Temperature
If your table includes a temperature-dependent film coefficient as a dependent variable, use one of the following independent variables to specify the temperature and how it is measured.
Average Film Temperature
Bulk Temperature
Surface Temperature
Difference of Surface and Bulk Temperature
Limitation:
Tables can include either the independent variable Y Coordinate (that is, table data in Cartesian coordinates) or the independent variable Theta Coordinate (that is, table data in cylindrical coordinates), but not both.
Tables can only include one temperature-related independent variable (Temperature, Average Film Temperature, Bulk Temperature, Surface Temperature, or Difference of Surface and Bulk Temperature).
The independent variable Temperature cannot be used in film coefficient tables. Instead, use one of the temperature-related independent variables listed above.
Although temperature-related independent variables can be included in a table of pressure loads, the Mechanical APDL solver does not currently use them when computing a solution.
Dependent Variables
Tables must contain at least one dependent variable, which represents a real physical quantity whose value depends on that of the independent variables in the table. The dependent variables that correspond to the supported boundary conditions are listed below.
| Boundary Condition | Dependent Variable(s) | Description |
|---|---|---|
| Pressure | Pressure | The magnitude of pressure normal to a surface |
| Pressure components (Pressure_i, Pressure_j, Pressure_k) | The X, Y, and Z components of a pressure vector | |
| Temperature | Temperature | The temperature on the boundary |
| Thermal Condition | Temperature | The internal temperature of the body |
| Convection | Temperature | The ambient temperature (or bulk temperature) of the fluid |
| Film Coefficient | The film coefficient along the boundary |
Limitation:
Pressure tables can include either Pressure or pressure components (Pressure_i, Pressure_j, Pressure_k), but not both.
Temperature cannot be used as a dependent variable and an independent variable in the same table.
Tables for convection boundary conditions can include both Temperature and Film Coefficient as dependent variables. However, the Mechanical APDL solver only loads one of these variables, depending on whether you assigned the table as the temperature or film coefficient magnitude. The independent variables in the table apply in both cases.
For example, suppose your table contains Temperature and Film Coefficient as dependent variables and Time as an independent variable. If you assign the table as the temperature on a convection boundary, the solver loads the Temperature values in the table and ignores the Film Coefficient values. The reverse is true if you assign the table as the film coefficient. In both cases, the solver loads the Time values in the table.
If you create a table with multiple dependent variables (such as Pressure and Film Coefficient), you can use this table to specify the magnitude of either a Pressure boundary condition or the Film Coefficient for a Convection boundary condition. However, the result from this scenario might not be logical, as you are applying a Film Coefficient table to Pressure or a Pressure table to Film Coefficient.