System Requirements

Energy2D runs on Java. For security reasons, it is strongly recommended that you download the latest version of Java from Your anti-virus software should allow applications from the domain to run.

Notes to Chrome users: As of April 2015, Java applets are not supported in the latest version of Chrome. Please use other browsers such as Firefox or Internet Explorer to view the applets of this website.

Notes to Mac OS X users: You need to install Oracle's Java (as of 2013, Apple has handed the development of Java for Mac over to Oracle). Unfortunately, the minimum version of Mac OS that supports Java 7 is 10.7.3 (Lion). So if you use Mac OS X 10.6 or lower, you will not be able to run the Energy2D applet (you can always run the Energy2D app, however).

Install the Energy2D App

Energy2D can be used in two ways: as a desktop app or as an embedded applet. There is also a plan to export simulations as HTML5 elements so that they can run within a browser without a plugin.

The desktop app is the full version of Energy2D, which is available for downloading in two ways: Install through a Web Installer or download the Java executable (energy2d.jar).

The Web Installer is the preferred way to install the Energy2D app. On Windows and Linux, clicking the Web Installer link will start the installation process. On Mac OS X, clicking the Web Installer link will cause a small zip file to be downloaded. Unzip the zip file and double-click the energy2d.jnlp in the uncompressed folder to install the app.

Sometimes, however, the Web Installer will not work if you disable Java for your browser. In that case, you can download the Java executable (energy2d.jar). The Java executable (energy2d.jar) does not run within a browser but still needs Java in your operating system. It can be run by just double-clicking on it. If you cannot get the online versions of Energy2D to work, use energy2d.jar instead — in our experience, it always works irrespective of your firewall or anti-virus settings. On Mac OS X, however, due to the Gate Keeper, you may need to right-click (or Control + click) on the energy2d.jar file and select "Open" from the menu, instead of simply double-clicking it.

Embed Existing Energy2D Simulations

You can easily embed an existing Energy2D simulation anywhere. Just copy the following code and embed it in your blog or wiki:

<applet archive="" code="org.concord.energy2d.system.System2D" codebase="" height="500" width="500" id="applet1">
<param name="script" value="load e2d/reynolds.e2d;"/>
<param name="permissions" value="sandbox"/>
<param name="MAYSCRIPT" value="true"/>

This way you can embed any simulation from our website in your web pages. Check out two embedded applets in a blog post.

Another advantage of embedding existing simulations from our website in your HTML files is that they can be run locally -- you do not have to put your HTML files on a server (they will still work if you put them on a server, of course). Here is an example HTML file that you can download and modify for your own use.

Deploy Your Own Energy2D Simulations Online

If you need to deploy the Energy2D applet on your own servers or embed it in your own online courses, download energy2d-applet.jar and copy the following HTML code:

<applet id="applet1" archive="energy2d-applet.jar" code="org.concord.energy2d.system.System2D" width="500" height="500">
<param name="script" value="load yourmodel.e2d;"/>
<param name="permissions" value="sandbox"/>
<param name="MAYSCRIPT" value="true"/>

yourmodel.e2d is an Energy2D simulation you create and name using the desktop app. You can download a sample .e2d file from here and use it to test your applet. You can arbitrarily adjust the width and height parameters in the above code to set the size of the applet window. Energy2D will rescale to any size you set.

For the Energy2D applet to work, your school's computer networks must allow energy-applet.jar and *.e2d files to go through your firewalls or antivirus systems.

If you are creating interactive Web content, you will also need a JavaScript file, energy2d.js for enabling interactions between Energy2D and other Web widgets. This file needs to be included in the head of your HTML page:

<script type="text/javascript" src="energy2d.js"></script>

Energy2D has many internal script commands that can be used in conjunction with JavaScript for Web development, as demonstrated by the online simulations on this website.

Source Code

You can download the Java source code of Energy2D from Github.

License and Copyright

Although Energy2D is licensed to you under the GNU Lesser General Public License V3.0, the license does not extend to the simulations you have created. Just like you own a document you wrote using Microsoft's Word, you own a simulation you designed using Energy2D. So feel free to distribute your simulations in the way you need.


Developed by Charles Xie. © 2010-2015 The Concord Consortium.