# TBC_DATA¶

Describes a thermal boundary condition.

Examples:

```
TBC_DATA tbctop
TEMPVD m C
800 29
1000 35
1200 41
END TEMPVD
CONN_D 1 50 1 50 1 1 Z-
END
TBC_DATA tbctop
TEMPERATURE 29 C
CONN_D 1 50 1 50 1 1 Z-
END
```

The options supported by TBC_DATA are:

## TINIT, TEMPERATURE¶

TINIT or TEMPERATURE define the temperature associated with a TBC_DATA thermal boundary condition. Temperature can be provided by a constant value, or using a table of temperature versus depth:

```
TEMPVD m C
800 29
1000 35
1200 41
END TEMPVD
```

TEMPVD requires to specify the depth unit, meter in the example above, while temperature are assumed to be in degree Celsius. A temperature table is a preferred option when the faces of a boundary are located at different depths, and the user want to assign values that follow the geothermal gradient.

## CONN_D¶

Specifies blocks of connections to attach aquifer to reservoir cell faces. Follows the ECLIPSE grdecl convention (K index is counted downwards from the top layer).

An example is:

```
CONN_D 1 9 9 9 1 1 Y+
```

Note that the connection box argument order is:

```
CONN_D IL IU JL JU KL KU
```

Where:

IL and IU are a range of cell indices in the I-direction

JL and JU are a range of cell indices in the J-direction

KL and KU are a range of cell indices in the K-direction

Connections will be made to cells with I-indices such that \(I \geq IL\) and \(I \leq IU\), etc.

The cell faces to attach the aquifer are specified by one of the following options:

X+ or I+, faces connecting cells with I-indices to cells with (I+1)-indices

Y+ or J+, faces connecting cells with J-indices to cells with (J+1)-indices

Z+ or K+, faces connecting cells with K-indices to cells with (K+1)-indices

The pairs (X- or I-), (Y- or I-) and (Z- or K-) follow the same logic, and are used to connect to cells with (I-1)-indices, (J-1)-indices and (K-1)-indices.

A number of CONN_D sub-keywords may be entered to build up the full connection. If the same face of the same cell is included more than once, only one connection will be generated.

## CONN_Z¶

Warning: keyword to be used only by proficient PFLOTRAN users. Unless there is some specific reason, consider using CONN_D instead.

Specifies blocks of connections to attach aquifer to reservoir cell faces.

CONN_Z use the convention that the K index is counted upwards from the bottom layer. For example:

```
CONN_Z 1 9 9 9 1 1 Y+
```

Note that the connection box argument order is:

```
CONN_Z IL IU JL JU KL KU
```

Where:

IL and IU are a range of cell indices in the I-direction

JL and JU are a range of cell indices in the J-direction

KL and KU are a range of cell indices in the K-direction

Connections will be made to cells with I-indices such that \(I \geq IL\) and \(I \leq IU\), etc.

The cell faces to attach the aquifer are specified by one of the following options:

X+ or I+, faces connecting cells with I-indices to cells with (I+1)-indices (GRDECL grid format).

Y+ or J+, faces connecting cells with J-indices to cells with (J+1)-indices (GRDECL grid format).

Z+ or K+, faces connecting cells with K-indices to cells with (K+1)-indices (K index counted upwards from the bottom layer).

The pairs (X- or I-), (Y- or I-) and (Z- or K-) follow the same logic, and are used to connect to cells with (I-1)-indices, (J-1)-indices and (K-1)-indices.

When using CONN_Z, the top faces of a reservoir with 100 layers are defined with Z+. See the following example:

```
CONN_Z 1 50 1 50 100 100 Z+
```