### 10.9.22. Parts - Zoning - Fill Block

This window lets you import complicated zoning and fill information, such as a city center consisting of many buildings of different size. The option is only available for Euler-FCT parts.

After browsing for an input file (extension .blk), select the format of the external data.

- Implicit format – Autodyn reads the fill flag of Euler-FCT cells in a certain predefined sequence. The fill flags of ALL the cells in the input region must therefore be defined in the data file.

- Explicit format – Autodyn reads the cell index together with its fill flag. Hence, only the buildings (unused) cells and the cells with target points need to be included in the data file.

The external file imported into Autodyn using the Fill Block option should have the extension .blk, for example block0.blk. Note that this file name is not necessarily the same as the ident of the Autodyn model that is being pre-processed.

The Fill Block command also permits extra air space to be created beyond the input region. For example, to allow a pressure wave to propagate over the tallest building in the model and interact with the buildings behind, Fill Block can be used to create additional air space above the building.

#### 10.9.22.1. Parts - Zoning - Fill Block Implicit

IMPLICIT | Fill type
IMAX, JMAX, KMAX | Maximum I, J, K indices of input region
XMIN, YMIN, ZMIN | Minimum co-ordinates of input region (corresponding to the node at I=J=K=1)
DX, DY, DZ | X, Y, Z zone dimensions for input region
XRAT, YRAT, ZRAT | Ratios used to extend grid beyond the original input region. For example, if XMAX is the maximum X-coordinate of the input region and XRAT=0.5, the generated grid would be extended to XMAX + 0.5 (XMAX-XMIN) in the X-direction, with geometric zoning being used automatically for cells above XMAX. The maximum I index of the part will be larger than the IMAX defined in the data file, hence extra elements are created to include the extended air space.
SIE | Unit-dependent specific internal energy for the air (2.068x105 is usually OK for the mm/mg/ms units)
IFILL | Fill flag of each cell in input region (K varying faster than J, J varying faster than I. Input 20 cells per line of dataIFILL= 0 Fill cell with unused IFILL= 1 Fill cell with air IFILL= 2 Fill cell with air and target point

An example of a .blk file using the implicit format is shown below. Note that the IFILL flag has to be defined for all elements in the part. The resulting filled Euler-FCT grid is shown in Figure 2.2.1.

#### 10.9.22.2. Parts - Zoning - Fill Block Explicit

EXPLICIT | Fill type
IMAX, JMAX, KMAX | Maximum I, J, K indices of input region
XMIN, YMIN, ZMIN | Minimum co-ordinates of input region (corresponding to the node at I=J=K=1)
DX, DY, DZ | X, Y, Z zone dimensions for input region
XRAT, YRAT, ZRAT | Ratios used to extend grid beyond the original input region. For example, if XMAX is the maximum X-coordinate of the input region and XRAT=0.5, the generated grid would be extended to XMAX + 0.5 (XMAX-XMIN) in the X-direction, with geometric zoning being used automatically for cells above XMAX. The maximum I index of the part will be larger than the IMAX defined in the data file, hence extra elements are created to include the extended air space
SIE | Unit-dependent specific internal energy for the air (2.068x105 is usually OK for the mm/mg/ms units)
I, J, K, IFILL | I, J, and K index of the cell and its fill flag. One cell per line of input. IFILL = 0 Fill cell with unused IFILL = 1 Fill cell with air (default) IFILL = 2 Fill cell with air and target point

An example of a .blk file using the explicit format is shown below. Note that only elements with an IFILL flag of 0 or 2 need to be defined. The default of 1 is assumed for all other cells. The resulting filled Euler-FCT grid is shown in Figure 2.2.2.

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