Neqsim

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NeqSim is the main part of the NeqSim project. NeqSim (Non-Equilibrium Simulator) is a Java library for estimating fluid properties and process design. The basis for NeqSim is a library of fundamental mathematical models related to phase behavior and physical properties of fluids. NeqSim is easily extended with new models. NeqSim development was initiated at the Norwegian University of Science and Technology (NTNU).

Documentation

NeqSim User Documentation

Index of reference manual

Releases

NeqSim releases are available as a packaged jar file and as source code. NeqSim can be used in a third party application by adding NeqSim jar to the classpath.

Getting started as a NeqSim Java user

NeqSim can be used in a Java application by adding the neqsim-x.x.x.jar found in NeqSim releases to the classpath. A demonstration of downloading the library and running a TPflash benchmark is illustrated in this NeqSim Colab demo. Learn and ask questions in Discussions for use and development of NeqSim. Also see the NeqSim JavaDoc.

Use of the NeqSim package

NeqSim can be set up as a dependency in a Java project via the NeqSim GitHub package distribution.

Using NeqSim from the GitHub Maven package repository

1. Configure authentication for the GitHub Packages repository in your Maven settings.xml (use a Personal Access Token with at least the read:packages scope):

<servers>
  <server>
    <id>github</id>
    <username>YOUR_GITHUB_USERNAME</username>
    <password>${env.GITHUB_TOKEN}</password>
  </server>
</servers>

2. Add the GitHub Packages repository and NeqSim dependency to your project's pom.xml:

<repositories>
  <repository>
    <id>github</id>
    <url>https://maven.pkg.github.com/equinor/neqsim</url>
  </repository>
</repositories>

<dependencies>
  <dependency>
    <groupId>com.equinor.neqsim</groupId>
    <artifactId>neqsim</artifactId>
    <version>3.1.2</version>
  </dependency>
</dependencies>

3. Build your project as normal (mvn clean install). Maven will fetch NeqSim from the GitHub Maven package repository using the credentials configured in step 1.

Using NeqSim from Maven Central

If you prefer to pull NeqSim from Maven Central, you only need to declare the dependency because Maven Central is enabled by default in Maven builds:

<dependencies>
  <dependency>
    <groupId>com.equinor.neqsim</groupId>
    <artifactId>neqsim</artifactId>
    <version>3.1.2</version>
  </dependency>
</dependencies>

Run your Maven build (mvn clean install) and NeqSim will be resolved from the Central repository without additional repository configuration.

Getting Started as a NeqSim Java developer

See the NeqSim Java Wiki for how to use the NeqSim API. Additional pages are available in the local wiki. NeqSim can be built using the Maven build system (https://maven.apache.org/). All NeqSim build dependencies are given in the pom.xml file. Learn and ask questions in Discussions for use and development of NeqSim.

Solve Engineering Tasks with AI

NeqSim includes an AI-assisted workflow for solving engineering tasks — from quick property lookups to full design studies — while simultaneously improving the toolbox.

LLMs are excellent at engineering intent but hallucinate thermodynamics. NeqSim is exact on physics but blind to context. Together, they form a complete reasoning engine:

Fastest way to start (requires VS Code + GitHub Copilot Chat):

@solve.task hydrate formation temperature for wet gas at 100 bara

The @solve.task agent creates a working folder, researches the topic, builds and runs a NeqSim simulation, validates results, and generates a Word report — all in one session.

Alternative (script-based, no Copilot needed):

pip install -e devtools/
python devtools/new_task.py "hydrate formation temperature" --type A

See the step-by-step tutorial or the full workflow reference.

Initial setup

The NeqSim source code is downloaded by cloning the library to your local computer (alternatively fork it to your private repository). The following commands are dependent on a local installation of GIT and Maven.

git clone https://github.com/equinor/neqsim.git
cd neqsim
./mvnw install

Note The maven wrapper command is dependent on your OS, for Unix use: ./mvnw Windows: mvnw.cmd

An interactive demonstration of how to get started as a NeqSim developer is presented in this NeqSim Colab demo.

Opening in VS Code

The repository contains a ready‑to‑use dev container configuration. After cloning the project you can open it in VS Code with container support enabled:

git clone https://github.com/equinor/neqsim.git
cd neqsim
# Open in VS Code with container support
code .

The container image comes with Maven and the recommended extensions already installed.

Running the tests

The test files are written in JUnit5 and placed in the test directory. Test code should be written for all new code added to the project, and all tests have to pass before merging into the master branch.

Test coverage can be examined using jacoco from maven. Generate a coverage report using ./mvnw jacoco:prepare-agent test install jacoco:report and see results in target/site/jacoco/index.html. Run ./mvnw checkstyle:check to verify that your code follows the project's formatting rules.

Note The maven wrapper command is dependent on your OS, for Unix use: ./mvnw Windows: mvnw.cmd

Deployment

The NeqSim source code is compiled and distributed as a Java library. NeqSim releases are available for download from the release pages.

Built With

Maven - Dependency Management

Contributing

See the getting started as a NeqSim developer documentation. Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests. An interactive demonstration of how to get started as a NeqSim developer is presented in this NeqSim Colab demo. See docs/DEVELOPER_SETUP.md for a summary of how to clone the project, build it and run the tests. For more details see the getting started as a NeqSim developer documentation. Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests. An interactive demonstration of how to get started as a NeqSim developer is presented in this NeqSim Colab demo. Pull requests will only be accepted if all tests and ./mvnw checkstyle:check pass.

For guidance on where to place production code, tests, and resources, see docs/contributing-structure.md.

Discussion forum

Questions related to neqsim can be posted in the github discussion pages.

Versioning

NeqSim uses SemVer for versioning.

Authors and contact persons

Even Solbraa (esolbraa@gmail.com), Marlene Louise Lund

Licence

NeqSim is distributed under the Apache-2.0 licence.

Acknowledgments

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