Tag Archives: applets

Using Energy2D to simulate solar updraft towers

The day/night cycle of an SUT
The solar updraft tower is a new-concept clean energy power plant for generating electricity from the sun. Sunshine falling on a greenhouse collector structure around the base of a tall chimney heats the air within it. The resulting convection causes air to rise up in the tower, driving wind turbines to produce electricity. In 2011, a plan of building a massive solar updraft tower in Arizona was announced (for more information, see this CNN report: Can hot air be the free fuel of the future?).

Compared with other solar technologies, solar updraft towers have many significant advantages. For example, it does not require water; it can be built in barren areas; it can still generate electricity after dark; its lifetime is much longer than solar panel arrays; and so on. Engineering-wise, it is a sound concept. The rest is a political will to get it banked and constructed. Let's hope it wouldn't take too long.
Streamline analysis of air intake

Instead of waiting for it to come true, why not go to our Energy2D website and see a bunch of simulations? You can even start to investigate it with our powerful Energy2D software. For example, you can turn the sunlight on and off to investigate how the heat absorbed during the day can still be released at night to drive the turbines. You can adjust the height of the tower to get an idea of why engineers want to build an insanely tall tower that rivals the height of Burj Khalifa in Dubai, the tallest building in the world. You can even use Energy2D's comprehensive analysis tools to study what happens when you block one of the air intake entrances.

The opportunities of inquiry with Energy2D are practically endless. You don't have to wait for someone to erect a solar updraft tower to explore about the technology -- you can do it now and the concept of a new technology is only a few mouse clicks away from you. Why not show these simulations and your investigations to your students to get them interested in clean energy today?

Using Energy2D to simulate Trombe walls

A Trombe wall is a sun-facing wall separated from the outdoors by glass and an air space. It consists a solar absorber (such as a dark surface) and two vents for air in the house to circulate through the space and carry the solar heat to warm the house up. In a way, a Trombe wall is like a machine that uses air as a convey belt of thermal energy harvested from the sun. Trombe walls are very simple and easy to make and are sometimes used in passive solar green buildings.

Hiding sophisticated power of computational fluid dynamics behind a simple graphical user interface, our Energy2D software can easily simulate how a Trombe wall works. The two images in this blog post show screenshots of a Trombe wall simulation and its closeup version. You can play the simulation on this page and download the models there. If you open the models using Energy2D, you should be able to see how easy it is to tweak the models and create realistic heat flow simulations.

Solar chimneys operate based on similar principles. Energy2D should be able to simulate solar chimneys as well. Perhaps this would be a good challenge to you. (I will post a solar chimney simulation later if I figure out how to do it.)

Energy2D V1.0 released!

The first stable version of Energy2D, an open-source and free heat transfer simulation tool made possible by funding from the National Science Foundation, is now available for download. The program can be installed as a desktop app, which can be used to create high-quality simulations that can be deployed on the Internet as applets. It comes with about 40 templates to help you get started to design your own simulations. The Energy2D website provides plenty of examples that show how you can integrate your simulations on your websites. The examples cover a wide range of topics in heat transfer, fluid dynamics, and thermal engineering. Thermal engineering is a major feature added recently and will be expanded in the future. The example to the right, "How solar cycles affect the duty cycle of a thermostat," showcases this new feature.

When you click the "Java Webstart Installer" on the website, the software will be automatically downloaded and installed on your desktop. The website's Download page has detailed information for how to publish your Energy2D simulations or integrate them with your web stuff.

If you have used the Energy2D app before, you will need to remove the previous installation in order to enjoy the convenience of full OS integration that this version offers. For Windows users, go to "Control Panel > Java." For Mac users, go to the Java Preference. In either case, you can find the previous installation in "Temporary Internet Files."

If you have just used the online applets on our website but haven't downloaded the app, there is nothing you need to remove. Although it is perfectly fine to use the online applets as they are, we think you should try the app--It will give you the full ability to create, design, and test.

Two Interactive Features Added to Energy2D

Energy2D is our signature software for heat transfer and fluid dynamics simulations. Written in Java, it runs speedily either as a standalone app on your desktop or an embedded applet within a browser. It is actively being developed to meet the need of energy education to have an interactive and constructive learning environment based on rigorous scientific principles. Energy2D is already a highly interactive system--you can change anything that is allowed to change by the author of a simulation while it is running. Recently, I have added two new features to make it even more interactive. Both features apply to all existing Energy2D simulations I (or you) have created.

The first one is a "heat dropper," a mode in which the user can click or drag the mouse to add or remove heat from the location in the model that the mouse points to. If you have a touch screen, you can touch or swipe your finger across it and the heat dropper works as if your finger could give heat to the virtual space in the simulation. The first video in this blog post shows how it works.

The second one is a "field reader," a mode in which the user can move the mouse to read the value of a property distribution field at the location the mouse points to. Currently, the supported property fields include temperature, thermal energy, and fluid velocity (which will be zero in a solid). The second video shows how it works.

If a web page that embeds an Energy2D applet doesn't already have a drop-down menu on the page for you to switch to these modes, you can always access them through the View Options dialog window. The View Options menu can be found if you right-click on a spot in the simulation window that is not occupied by a model component (like a polygon or a sensor).

An online gas lab simulation

Go to simulation.
You probably know the Ideal Gas Law well. An ideal gas is a hypothetical gas made of randomly moving particles that do not have a volume and do not interact with one another. Have your students ever asked questions such as "What about non-ideal gases? How good is the Ideal Gas Law for real gases?" I don't know about other people's experience, but I myself was intrigued by those questions when I learned the gas laws. Unfortunately, I couldn't go too deeply in trying to answer them because just thinking about the complexity of the motion and interaction quickly intimidated me.

Before computer simulation was widely accessible, you probably would have to pull out the Van der Waals Equation and pray that doing the math would do the trick.

Now, there is a good way to teach this. Using an online molecular dynamics simulation--made using the Molecular Workbench software, investigating non-ideal gases is a piece of cake. This simulation uses a pair of gas containers side by side and allows the user to explore how six variables affect the volume of  a gas: temperature, pressure, number of particles, particle mass, particle size, and particle attraction. It basically covers all the variables in the Van der Waals equation--without saying them explicitly. And there is a variable that is not included in the Van der Waals equation. The simulation reveals exactly why it is not there.

Theo Jansen’s mechanism

Go to the simulation
Theo Jansen is a Dutch artist and kinetic sculptor who builds large works that resemble skeletons of animals that are able to walk using the wind on the beach. His works are a fusion of art and engineering.

Theo Jansen's famous mechanism can be simulated by using the Molecular Workbench software. Shown in this blog post is a screenshot of the simulation. You can click the link below the screenshot to watch the simulation.