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 # Introduction 

 Last update: 24.03.2026 

The Ansys Common Fluids Format SDK is a collection of APIs, data models, and example programs that allow you to access or write data to Ansys Common Fluids Format files using a common format that is also used by Ansys Fluids products.

The Common Fluids Format SDK is made up of:

- [Application Programming Interface (API)](index.xhtml#API)
- [Data Models](index.xhtml#DataModels)
- [File Formats](index.xhtml#FileFormats)
- [Examples](index.xhtml#Examples)



## <a class="anchor" id="API"></a>Application Programming Interface

### <a class="anchor" id="Prerequestites"></a>Prerequisites for using the Application Programming Interface

Refer to the [Requirements](_requirements.xhtml) section in this document, which details the prerequesites you should consider before using the Ansys Common Fluids Format SDK.

### <a class="anchor" id="BriefAPIOverview"></a>Overview

The Application Programming Interface (API) provided within this SDK provides you with a number of classes, functions, and enumerated types that allow you access to read in existing files and to write your own data to new files.

If the API is used correctly, your own files will be readable within selected Ansys Fluids products.

**Note:** To enable you to read or write files correctly using the API, it is important to understand the [Data Models](index.xhtml#DataModels) that are used by the API to describe the data and the relationships between data held within those models.

For further information see

- [Ansys Project API](_project_a_p_i.xhtml)
- [Ansys Common Fluids API](_c_f_f_a_p_i.xhtml)

## <a class="anchor" id="DataModels"></a>Data Models

Use of the Common Fluids API depends on the understanding of how data is held within the models of the data that are typically provided by Computational Fluid Dynamics (CFD) software.

A number of data models exist:

- [Project Data Model](_data_models_overview.xhtml#ProjectDM)
- [CFF Restart Data Model](_data_models_overview.xhtml#RestartDM)
- [CFF Post Data Model](_data_models_overview.xhtml#PostDM)

A model is an abstraction of the data. Each model consists of a number of submodels that each hold related data.

The three core data models mentioned above correspond to the concrete implementations of each model in the [Files](index.xhtml#FileFormats) listed below. In the future it may be possible to access implementations of these models from other data sources.

## <a class="anchor" id="Files"></a>Files

Representing the models used to hold the complex CFD data as files allows the user to save and recover data between sessions and between applications. Each of the models previously mentioned has a corresponding file format.

### <a class="anchor" id="FileFormats"></a>File Formats

Three distinct classes of file are used by the CFF:

- [Project File Format](_file_formats_overview.xhtml#CFFProject)
- [CFF Restart File Format](_file_formats_overview.xhtml#CFFRestart)
- [CFF Post File Format](_file_formats_overview.xhtml#CFFPost)

Each in turn corresponds to the [Data Models](index.xhtml#DataModels) previously mentioned. The [APIs](index.xhtml#API) provide you with access to the data held within each file.

You do not need to know how or where the data is stored in the files, instead you should rely on the [APIs](index.xhtml#API) and your knowledge of the specific [Data Models](index.xhtml#DataModels) when reading from or writing.

## <a class="anchor" id="Examples"></a>Examples

Source code examples are provided in [Examples](_c_f_f_s_d_k_examples.xhtml).

One example reads given case and results files, another example writes a simple case and data file. There are also two 'C' examples that illustrate how to use the 'C' API for reading and writing a CFF case or results file.

All examples include comments that provide guidance on use of the [API](index.xhtml#API) and associated [Data Models](index.xhtml#DataModels).

Further examples are included to demonstrate more specific capabilities of the API, such as parallel write.