Accelerating premium artisanal gelato production with computational fluid dynamics simulation

Using CFD to continually innovate

R&D CFD is a leading Italian engineering company based in Modena with expertise in computational fluid dynamics (CFD). Founded in 2012 by Giuseppe Cicalese and Professor Dr. Stefano Fontanesi, the company emerged from a successful research collaboration.

Today, they’ve built an impressive portfolio of satisfied customers across multiple industries, from automotive to food and beverage.

The gelato challenge

R&D CFD was approached by a leading Italian gelato manufacturer renowned for their premium swirled artisanal packaged gelato with ribbons of sauce woven throughout in flavors like chocolate, strawberry, caramel and peanut butter. After years of perfecting their recipe, the taste was world class: creamy, rich and dense.

But in the highly competitive food and beverage market, looks matter just as much as taste. The manufacturer needed their variegated gelato to be visually stunning: soft, smooth, silky and elastic with natural colors. Better aesthetics means better sales and happier customers.

“The customer wanted our help to predict how their variegated ice cream would look at the end of their manufacturing process,” says Cicalese. “People who buy this ice cream are looking for a certain handmade feeling. But how do you make it look handmade in a machine?”

Revisiting the production process and equipment

The secret to perfect variegated gelato lies in the variegator – the machine that is used to mix ice cream and sauce from separate feed lines. The manufacturer’s existing variegator had a static design with no moving parts, but it was complex. Ice cream and sauce contacted screws, baffles and walls, making it difficult to control the mixing process and sauce pattern. Worse, the product was exposed to air, a major quality issue for premium gelato. Plus, all those parts meant longer cleaning times and more downtime.

The manufacturer opted for simpler equipment with two concentric cylinders – one for ice cream, one for sauce – connected by a nozzle. The ingredients mix directly in the variegator with no screws, baffles and wall interaction. This equipment provided just clean, controlled mixing, easier cleaning, better control and more beautiful sauce swirls. On paper, the new design was perfect.

Engineering gelato quality with CFD simulation

However, they quickly realized improvements were necessary. They needed to predict how the gelato would look after manufacturing before being stored in boxes, and that’s where R&D CFD’s simulation and design optimization expertise proved invaluable.

As advanced users of Simcenter™ STAR-CCM+ ™ software combined with their deep understanding of flow and thermal dynamics from other industries, the team could make well-informed design enhancements. Using Simcenter HEEDS™ software, they analyzed the performance of hundreds of design variations and scenarios to find the optimal solution. “We decided to use our Simcenter engine simulation tools to improve the variegator design,” says Cicalese. “With digital simulation, we could reduce the number of prototypes and save time and cost in design. It also helps us analyze hundreds of designs.” Both software programs are part of the Siemens Xcelerator business platform of software, hardware and services.

“Simulating ice cream and sauce is not as simple as simulating air and water,” says Cicalese. “They are gooey, viscous, elastic fluids. Understanding the rheology and thermal behavior took some time.” Simulating these viscoelastic fluids with CFD is challenging. With Simcenter, they could model such challenging physics thanks to a volume of fluid (VOF) multiphase model and a comprehensive rheology model. The rheology model can use a function or a data set to connect the viscosity with shear.

The software was able to model the ice cream, sauce and the interface between the two accurately. “In the past, we worked with other simulation software where the process was far more difficult,” says Cicalese. “What we enjoy about working with Simcenter STAR-CCM+ is the variety of physics you can simulate in a coupled manner, from engines to ice cream.”

Leveraging Design Manager, a Simcenter technology used to explore the entire specified space, the R&D CFD team modeled 2,000 design scenarios, changing the nozzle geometry and operational physics laws to inject sauce. The software automatically searched for the optimum design based on the constraints, goals and parameter range of the design. It found the design that produced the best sauce pattern and swirl and avoided prototyping and building the extensive number of design variants for real-world validation.

Achieving production speed and consistency

For mass production, the variegator needed multiple nozzles for faster operation. All these nozzles need to be fed the same quantity of sauce from the feeding chamber. This way, the ice cream in every box was identical in appearance and texture, ensuring customer satisfaction. The team used Simcenter to automatically analyze different geometries of the sauce feeding chamber and the resulting sauce distribution. After reviewing 80 designs, he identified the best feeding chamber design.

As a result, all the nozzles receive the same amount of sauce, which was a significant achievement. “You can automate and optimize so fast with Simcenter HEEDS or Design Manager,” adds Cicalese. “You can see how the optimized design gives the same beautiful swirl to the sauce from every nozzle compared to irregular patterns from the initial design.”

Making global impact

R&D CFD’s improved variegator design is now being used in all of the customer’s manufacturing plants. As simulation predicted, it now has top-notch variegation. The team at R&D CFD experienced something unique: they were eating something they helped engineer. “I’ve tried the gelato and I’m very appreciative of the job we did,” says Cicalese. “It looks delicious and it tastes delicious.”