Rocky DEM Users Will be Forced to Migrate, Ansys Confirms

What users of the particle simulation tool could lose or gain after acquisition.

Disclosure: Shawn Wasserman is a former employee of Ansys Inc. who owns minor Ansys company stock.

Back in April 2021, I predicted that the announcement of Ansys Rocky, a repackaging of the ESSS Rocky DEM software with tighter integrations into the simulation giant’s portfolio, was a signal that it would gobble up the technology though an acquisition. Now in the opening week of 2023, that prediction has been proven correct. 

“The Rocky team is elated to join Ansys and further combine Rocky’s state-of-the-art particle simulation capabilities with Ansys’ flagship simulations—allowing engineers to design more reliable products, slash development time and win the race to market,” said Marcos Damiani, numerical development principal at Rocky.

A simulation of a pharmaceutical tablet coating process made using Ansys Rocky and Ansys Fluent. (Image courtesy of Ansys.)

A simulation of a pharmaceutical tablet coating process made using Ansys Rocky and Ansys Fluent. (Image courtesy of Ansys.)

So, what does Ansys, and its user base, gain in the acquisition? In short, Engineering Simulation and Scientific Software’s (ESSS) Rocky DEM and its support teams have been added to the simulation giant’s family.

Russ Hartz, vice president of Corporate Development at Ansys clarified to that they “only acquired from ESSS the Rocky software, related IP and software development, support and customer-facing team members focused specifically on Rocky by purchasing the equity of a particular ESSS entity in Spain and its Brazilian subsidiary. ESSS will continue to operate its reseller and other businesses through its various other entities as an independent organization.”

Two Rocky II: Electric Boogaloo?

In April 2021, Ansys explained to that Rocky DEM and Ansys Rocky would remain two separate software options.

At the time, Jeremy McCaslin, manager of fluids product management at Ansys said, “[Between] Ansys Rocky and ESSS Rocky DEM, there is some slightly different product packaging, but in terms of the actual technology and the scope of problems that they can solve, they are exactly the same—they are identical.”

He also explained that Rocky DEM was capable of one-way and two-way coupled simulations with Ansys technology and was fully integrated into Ansys Workbench. So, how did the two Rocky software options differ? The answer at the time was that there was no need for users to choose one over the other; rather, the new tool simply presented a better way to integrate the discrete element modeling (DEM) technology into the company’s portfolio, expand compatibilities and simplify the sales process.

McCaslin said in 2021, “The more customers we have that are using Rocky, the more feedback we will have as to how we could improve it with respect to our other tools and how it couples with them. We will have much more field inputs to use to enhance the integration of these tools.”

In other words, the simulation giant no longer needed to send potential Rocky customers to ESSS because they could just sell Ansys Rocky. It was this lack of differentiation, and the fact that the new product fit the simulation giant’s product naming scheme, that led me to believe this was merely a Band-Aid solution to solve the challenges of rebranding products before an acquisition was about to start.

How has this all changed with the recent acquisition? Hartz explained that they “previously resold ESSS Rocky DEM software under the product name ‘Ansys Rocky.’ Ansys will develop a thoughtful migration plan for the transition of ESSS Rocky DEM customer to Ansys Rocky moving forward.”

The Gaps Rocky Fills

Over the past 23 years, Ansys has made it a point to regularly acquire companies, often former partners, which helped to fill their portfolio from a technology and/or a user experience perspective. This pattern has been in full swing since the start of 2022; during that time, they have purchased five other organizations:

  1. Rocky DEM
  2. DYNAmore
  3. C&R Technologies (read more here)
  4. Motor Design Limited
  5. OnScale (read more here, and here)

For an example of how these acquisitions fill in the simulation giant’s portfolio, first consider OnScale. It offers the company a cloud-based platform which can be used to bring their other tools into a web-based software-as-a-service user interface. Clearly, this acquisition can be listed as both a benefit based on user experience and technology in that it includes OnScale’s simulation solvers as well.

Jane Trenaman, senior director Product Management focusing on Cloud and Portfolio at Ansys, said in May 2022, “The OnScale acquisition extends Ansys cloud technologies to include a cloud-native, web-based user interface… This supports and accelerates Ansys’ existing platform-centric approach to creating a new class of simulation-based vertical applications.”

Meanwhile, C&R Technologies was more of a technology acquisition that helped Ansys improve its thermal simulation offerings to include electrification, battery heat and spacecrafts. The role that the Rocky DEM acquisition will play is more akin to this.

“Rocky’s unique approach to discrete particle modeling empowers our customers to solve a wide variety of problems across virtually all industries,” said Shane Emswiler, senior vice president of products at Ansys. “Fully integrating Rocky into Ansys’ portfolio and welcoming its distinguished experts to our team builds upon our demonstrated success and enables Ansys to provide an even more efficient and powerful solution for our customers. We are delighted to welcome Rocky into the Ansys family.”

In other words, it’s the DEM technology that interests the simulation giant. This shouldn’t be a surprise since back in April 2021 I reported that the company doesn’t have a way to model particle movements at the length scales that Rocky can. Back then, McCaslin noted, “We don’t have a way of treating the bucket loader that’s scooping up gravel and the gravel itself within the same modeling framework. The same can be said for CFD examples. If you had, let’s say, a fluidized bed reactor… Rocky adds major value to the core problems that Mechanical and Fluent are trying to solve.”

Rocky specializes in simulating the dynamics of discrete solids and particle-laden free-surface flows. As a result, this addition to Ansys’ Portfolio makes it more desirable to the pharmaceutical, oil and gas and food and beverage industries that produce products ranging from powders, pills, fibers and slurries.

Additionally, by owning the technology outright, the simulation giant can better integrate it into its other products to unlock more synergies. My first guess would be to incorporate the GPU capabilities into Ansys Discovery, the lightning-fast GPU-based simulation tool. However, another synergy mentioned in the press release was the inclusion of Ansys Rocky into the Open-Source PyAnsys framework. To learn more about that framework, click here.

Written by

Shawn Wasserman

For over 10 years, Shawn Wasserman has informed, inspired and engaged the engineering community through online content. As a senior writer at WTWH media, he produces branded content to help engineers streamline their operations via new tools, technologies and software. While a senior editor at, Shawn wrote stories about CAE, simulation, PLM, CAD, IoT, AI and more. During his time as the blog manager at Ansys, Shawn produced content featuring stories, tips, tricks and interesting use cases for CAE technologies. Shawn holds a master’s degree in Bioengineering from the University of Guelph and an undergraduate degree in Chemical Engineering from the University of Waterloo.