Within modern food processing, a phenomenal amount of time can be spent testing and refining products before aspects such as taste are even considered. Computational fluid dynamics (CFD) is not a term that many associate with food, being more at home in engineering settings, but could help processing companies to significantly reduce their testing and development time.

Tetra Pak has been using CFD for over 15 years to analyse and simulate several aspects of food creation, and has recently released a white paper highlighting the importance of the process. CFD expert for Tetra Pak Dragana Arlov helps explain exactly what CFD is, and how Tetra Pak are using it to enhance processing within the food industry.

Elliot Gardner: What, in layman’s terms, is computational fluid dynamics?

Dragana Arlov: CFD has been around since the early 20th century, familiar to many as a tool for analysing the way that air flows around cars and aeroplanes.

Today, the tool has enhanced and is used in a variety of industry sectors that utilise fluids, employing numerical solutions in order to optimise the flow possibilities inside a processing component.

Values such as velocity, pressure, temperature and turbulence are obtained from the multiple simulations. In fluid applications, these values are then used to visualise the fluid flow fields at different locations inside apparatus like heat exchangers, pipes and mixing tanks.

EG: Why use it within food?

DA: Given the importance of mixing ingredients during food processing, Tetra Pak applies CFD to simulate precisely what happens in a mixer, virtually.

By running simulations of what happens inside a mixer, we can run virtual experiments quickly with the same results as physical experiments. And so, reducing the need for physical experiments in the design phase, which not only broadens the range of testing opportunities, it also reduces the chances of issues arising when mixers are installed at production sites.

Ultimately, CFD ensures the final design and configuration of a mixer are optimised for the specific requirements and applications the customer is looking for.

EG: What are the benefits of using CFD?

DA: There are several ways customers can benefit from incorporating CFD into their operations:

Firstly, by using validated ‘virtual mixers’, fluid dynamic simulations differ only minimally from experimental data. This means we are confident that the mixers we design will always give the desired results for our customers.

Secondly, making a ‘virtual mixer’ takes far less time than building several mixer prototypes and performing consecutive tests. Furthermore, it is faster and cheaper to vary the process parameters in computer simulations than it would be to stop on-going production and run physical tests. We have seen that using CFD can reduce testing time by up to half a year. In addition, the end design is optimised and the mixer requires less power, reducing the cost of ownership for our customers

Thirdly, computational simulations provide us with detailed information that contributes to our understanding of the mixing process. Important process parameters are identified and can be improved. The result is a rapid, reliable mixing process that is, most importantly, adapted to produce a product of the desired quality.

Food manufacturers, and consumers, insist on a perfect product every time. To achieve this, it is important to stay in complete control of every aspect of food production from beginning to end.

Due to the application of CFD at Tetra Pak, customers can be confident that the processing equipment will be optimal from a fluid flow perspective, as well as access to knowledge on mixers and how to scale up.

EG: Do you have any other examples of CFD in use in the food processing sector?

DA: We also use CFD to investigate other processing components such as heat exchangers, spray dryers, ice cream and flash vessels. 

EG: Which products is CFD most effective in use with?

DA: CFD is an effective way to evaluate and understand many different product types, however for some it is particularly crucial. For example, water behaves in a relatively straight-forward way, but highly viscous fluids like tomato products and cream cheese, which are more difficult to mix, require different simulation approaches.

EG: Can anyone use CFD within their processing setup, or does it require specialised technology?

DA: We are working with plant managers, R&D managers and engineers across the food industry to help them understand how CFD can be used to optimise the mixing of their products.

EG: How much computing power does CFD require?

DA: To operate CFD analysis and conduct the efficient, fast calculations required, Tetra Pak has built a dedicated computer cluster. Since a typical mixer simulation takes a few weeks using 200 computers, our 8,000 computer capacity allows us to run numerous simulations within a couple of days.

EG: How expensive is the set-up?

DA: Running a CFD simulation would cost €6k, if a new design is proposed, and €2k, if you’re re-using a design but changing operational parameters.

Included in this cost is set-up simulation, CPU-cost and analysis of all important flow parameters at all desired locations.

Building a tank would cost €30k including some flow parameters at some specific locations.