### 21.2.3. Working with Export Results

The topics in this section include:

- File Naming Conventions

- Propagating Older Time Step Values

- Output Boundary List and Output Region Naming

- Output Variables List

#### 21.2.3.1. File Naming Conventions

Each instance of an `Export Results` object will correspond to a particular group of files in a transient run.

Transient data is written into a series of files, named using the form:

`<prefix>_<timestep>.<extension>`

- `<prefix>` defaults to the `Export Results` object name unless you override this with the parameter “Filename Prefix”

- `<timestep>` is a string containing the timestep number

- cgns is the only available `<extension>`

The mesh information (mesh coordinates and nodal area vectors, if applicable) is written into a separate file to save disk space, because the mesh information does not change with time. The mesh filename is of the form:

<prefix>_mesh.cgns

A link is created for each solution file (<prefix>_<timestep>.cgns) to map the mesh coordinates to the mesh file (<prefix>_mesh.cgns). If you write your own reader, you need not open the mesh file separately to read in the mesh coordinates for each solution file.

#### 21.2.3.2. Propagating Older Time Step Values

When exporting results to 3rd party applications, it is possible that values from an earlier time step are written at time steps where true data does not exist - for example at time steps where minimal results files were requested in the solver control setup. This is done because some 3rd party software can only successfully read exported files when a consistent number of variables exists in each file. It is up to you to recognize that these “dummy variables” are not accurate at the particular time step.

#### 21.2.3.3. Output Boundary List and Output Region Naming

The default behavior of this parameter is to attempt to create one composite boundary region per domain. The boundary condition patches do not have to be in the same domain so that rotating dipole sources and regular dipole sources will be contained in the same export file if this is desired.

Each export surface object name is unique. If the export surface lies within one domain, the name of each exported surface will simply be the `Export Surface` object name. If the export surface lies across multiple domains, a region will be exported for each domain spanned by the export surface. Such regions are named using the form "<domain name>.<export surface name>".

#### 21.2.3.4. Output Variables List

When either of the acoustic options are selected, the output variables list is implied. For both acoustic options, there is output for pressure on vertices and the surface mesh (x, y, z and topology). For the rotating dipole option there is also output for nodal area vectors.

Release 18.2 - © ANSYS, Inc. All rights reserved.