While doing research for an article about SimScale’s new joule heating analysis capabilities, I found a post on the company’s CAE forum from July 2016. In it, a user named johnstockton said, “I am back to my usual difficulty in predicting Joule heating in a circuit. I was just wondering if there are other users in the SimScale community who have a similar need for simulation of heating of materials by current flow?”
SimScale product manager, Richard Szoke-Schuller replied. After first asking how much of a demand such a feature would have, he gave a generic approach to analyze Joule heating: solve the electric potential, compute the heat source from the electric potential using Ohm’s Law and apply that heat source as the load during a thermal analysis. Now, in 2023, SimScale has proven that it took johnstockton’s request to heart as it announced the addition of a Joule heating simulation study for power electronics.
The Munich, Germany SaaS simulation company prides itself on providing a multiphysics platform, and then finding new ways to spread that physics expertise into additional applications and simulations. With 400,000 users it might be a misnomer to call SimScale a ‘small’ simulation company, but the software is not a household name like Ansys or Altair. However, the Joule heating application is proof that SimScale is not satisfied with keeping the status quo and is bringing in new tools on a consistent basis to stay competitive.
SimScale Explains Joule Heating and Its Implementation
One of the things I like about Simscale is its commitment to educating simulation users. The company’s SimWiki documentation site is set up to teach novice users about simulation as a whole—even those that don’t specifically use the SimScale software. A novice user or decision-making engineering manager could use these sections to understand what engineers need to make better product and process decisions.
Fans of wiki learning can work through different menus and levels to reach the Joule heating page, nestled in the Thermal Analysis section. Different software companies place informational blurbs like this in different places—like password restricted tutorials, help me pages or equation and formula pop-ups—but having the information laid out like this is a great way to give users a sense check before delving into a deep thermal study.
“Joule heating is the physical effect by which the pass of current through an electrical conductor produces thermal energy,” says the wiki page. This conversion between electrical energy and thermal energy really hammers the point home. Joule heating, like many simulation questions, comes down to physics. The thoroughness of the information in the wiki is massive in its depth and breadth, moving from root mean square discussion to resistivity values of different materials to the applications of Joule heating, all presented with references.
For instance, as a big fan of beer, I was happy to learn from the wiki that James Prescott Joule’s work comparing electrical motors and steam engines was done in his family’s brewery.
How Does SimScale Simulate Joule Heating?
Alexander Fischer, co-founder at SimScale wrote an article entitled, “SimScale Launches Joule Heating Simulation to Accelerate Innovation in Power Electronics.” In it he talks about the addition of Joule heating-specific simulations in Simscale and the process of building these studies. One of the great points made here is that Joule heating can be deliberate, like heating units or incandescent lightbulb filaments. But, almost more important are the places where the Joule heating is not intentional, and engineers need to decide what to do with all the thermal energy generated by a circuit. Electronics components are especially sensitive to jumps in heat energy, especially components or assemblies with ideal operating temperature ranges.
Heat transfer simulation engineers now have the option to turn on a Joule heating analysis to study the additional heating type. Engineers can classify materials as isotropic or orthotropic conductors to tell the software if material properties are the same in every direction or three perpendicular directions. Current inflow and outflow are specified next in the boundary submenu.
The end of the process is the output stage. Current density, potential and Joule heating energy are all available outputs for the user. The electrical potential visualization gives engineers a look at places where voltage drop is happening in the system. Current density outputs tell the engineers where spikes occur, looking first at sharp edges cross-section shifts and then throughout the rest of the system. Joule heating results show where heat generation is higher or lower and finds sources where thermal energy will unexpectedly occur.
The example on the announcement page shows an inverter used in racing applications, full of MOSFET transistors and capacitors. Other applications discussed are resistor designs, electric batteries and fuse blocks. If the trend of vehicle electrification continues in the next decade, there will be more and more power electronics applications that need Joule heating studies performed. Engineers are trying to build sustainability into components and processes and understanding how thermal energy will affect designs can only make things a little easier.
What Does It All Mean?
One recent trend in simulation software is the idea that a free software version with limited features is almost necessary to compete and stay relevant. Academic versions or versions with fewer features are a great way to create users in a university or undergraduate setting, before sending them out into the field to become paying customers or possibly leaders who make purchasing decisions.
This, however, is the cynical way to look at low-cost or free versions of software. Many companies are also trying to offer their tools to as many users as possible to make the world a better place. My favorite quote about open-source simulation software comes from James Scapa of Altair: “For us, the purpose of Altair, in general, is really just to advance humanity.” If you’ve created something that you hope will have some small part in making the world a better place, why not let some users access that thing for zero or low cost? SimScale is no different, with a community version of the platform that gives users ten unrestricted simulations and up to 3,000 core hours.
Smaller engineering companies trying to decide which simulation software to use have a big decision. Cost, customer service and depth of product all factor into purchasing decisions. Like the bigger well-known options for simulation software, Simscale is available through the cloud on a pay-as-you-go model and customers can range from one to hundreds of users at a firm. Some of the company’s high-profile partnerships in the last few years produced the ability to use Simerics software through the Simscale interface and a tighter integration with Fusion 360 and Onshape CAD models.
Working with more CAD tools to bring in native models instead of relying on STEP and IGES files is a great indicator that Simscale knows what its customers need and is working to find options that will give a streamlined process with the goal of better and faster results. Simscale also continues to build on its existing functions, with this new Joule heating application and the recent addition of multi-phase flow simulation.
When users and super-users of a software ask for new features, as John did in 2016, software companies have several options available. It’s interesting to see first that there was a process to follow to understand a system’s Joule heating effects in 2016, and that the process has now been outlined in the software as a new capability. The needs of simulation engineers are growing and changing constantly, simulation software companies need to be aware of current trends and trends five or ten years ahead. Simscale looks like a company doing the right things in terms of partnerships, user interaction and creating updates for future engineers.