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Digital simulation accelerates the transition to a sustainable society

CFD - powerful tool making the future sustainable

Thommy Nilsson is section manager for one of AFRY's departments specialized in Computational Fluid Dynamics (CFD) and his experience within the field of Computional Aided Engineering stretches back to the 1980s. In this article, he describes how CFD technology such as analysis, simulation and calculation, is used to accelerate the transition to sustainable society.

Computational Fluid Dynamics (CFD) is one of the powerful tools AFRY's department of Technical Analysis and Simulation uses to support customers in decision making during product development, large infrastructure projects and design of process equipment. The digital simulation can predict and visualize different scenarios and with the aid of AFRY’s combined knowledge of cross functional experts experienced in a large number of different industries, both accuracy and precision reach high levels of reliability.


As the name (Computational Fluid Dynamics) suggests, the technology can be used for anything that flows. Thommy has been at AFRY long enough to have seen CFD being applied to most things from solid particles and liquids in food production to the worst-case scenario in the energy sector. In the automotive industry, the CFD technology is widely applied to improve everything from the vehicle's air resistance and thus fuel economy to ensuring efficient defrosting of the windshield. Airflows for simulation of indoor climate, ventilation and outdoor environment are other common applications in assignments.

People discussing in a creative office space

Thommy Nilsson

Thommy Nilsson has a Master of Science and a broad background in engineering calculations and simulations, hi has stayed in the field of Computonal Aided Engineering (CAE) and adjacent areas since the 1980s.

His experience stretches from disciplines as strength, fatigue, fracture mechanics, nonlinear analysis, dynamics and acoustics all the way to thermodynamics and fluid mechanics. Has been active in several industries such as automotive, nuclear, defense and oil & gas. Current position as section manager for one of AFRY's departments specialized in Computional Fluid Dynamics (CFD), calculations and simulations and structural mechanics (FEM).

Foremost it is a matter of producing reliable decision bases, for infrastructure projects and urban planning. All in all with minimal resources simulate worst case scenarios and determining factors leading to the best outcome without any impact on health or the environment. Thommy summarizes

Pipes ventilation

The importance of parameters

Learning and understanding the software alone will not suffice. The key to success is choosing correct parameters for input. The choice of parameters determines whether the result is best outcome or not, Thommy explains:

The factors you put in to the model need to be relevant, adequate and sufficient to cover all necessary details with respect to the purpose. That’s where AFRY excels, our combined knowledge, experience and shared in a vast network with generous culture exceeds by far any specialist, no matter how experienced, educated, and skilled.

Once a calculation model is created and verified, you can easily test different changes and see what effect they have. Compared to building different physical test models, something that in many cases is nor practically neither possible, you save a lot of resources - both time and money. Being able to test a larger number of different variants, give you greater probability to find the best solution and from a sustainable environmental perspective it might be finding the most energy-efficient solution.

Basis for decision making

CFD is the preferable digital program for predicting the outcome of suggested changes and determine which factors have the greatest impact on the outcome.

In the digital environment, reliable decision-making is created completely without risk to health and environmental impact. In addition, it is a cost-effective alternative considering how many different scenarios can be developed in such a short period of time.

Analysis Simulation two men looking at simulation through mobile device in lab

Indoor climate from several perspectives

Air conditioning is available in all rooms where people stay. Purpose and function are adapted to the business and the differences in personal risk in the event of downtime are large. There is of course a difference in consequences if the ventilation fails in a store compared with a down time in an infection ward. The simulation technique is the same but the number of parameters for input can be adjusted so the result gets the right, sufficient, precision.

Thommy lists his favorite assignments below:

theatre with crowd audience

Theater premises

With analysis and simulation, the theater premises were climate-secured with regard to both climate-proofing a theater with regard to temperature, draft and fresh air.

"The purpose was thus to ensure sufficient air flow to ventilate carbon dioxide, theater smoke that is, and at the same time we need to maintain an even and comfortable temperature, as well as prevent any whiff and winds around the audience, Thommy says."

Hospital facilities

In the article Tomorrow´s design of hospital ventilation describes how CFD technology can be used to predict the effect of point extraction. With the right design and placement, the effect is optimized, and minimizes the spread of an airborne virus. Even though Thommy himself was not involved in this project, it is important for him to mention it.

"I am grateful and proud to work at a company that follows developments in the world and quickly adapts to prevailing circumstances with the aim of increasing safety in this case reducing the risk of infection by healthcare professionals."

computional fluid dynamics simulation patient spread of particles
pressure-gbbfdb7499_1920 Pressure Equipment Directive PED  Manometer

Working next to high pressure tubes

Premises were people resides in the same room as gas tubes we need to ensure that the ventilation is sufficient so as not to endanger the health of those in the room if, for example, a tube with nitrogen gas starts to leak.

"Personal safety comes first and foremost, and maintaining a high level of safety in the work environment in a business that cares for weak and sick individuals is of course a high priority and gives meaning to the work," Thommy says

Simulation of outdoor environment in community planning and new construction

When it comes to the outdoor environment, it is above all calculations and simulations of unwanted gases that are in demand. It can be toxic or foul-smelling gases that must not be spread to the wrong places.

Public sectors within community planning are frequent clients, Thommy says and continues, but also private entrepreneurs who want to demonstrate that their planned operations and new constructions and buildings do not affect the environment in a negative way.


Framing of questions that we at AFRY answered using CFDs are for example:

  • Can we build a garage next to the preschool without the risk of the children being affected by harmful gas and airborne particles?
  • Can we construct this building without disturbing residents in the immediate environment with foul-smelling air.
  • Will this design of the neighborhood create strong wind streets?
  • Will emissions from new industrial premises affect nearby air traffic?
Computational Fluid Dynamics simulation traffic TA
TA CFD insight Thommy nilsson Simulation

Challenges - the right accuracy and level of detail

Often the challenge is to build simulation models at a reasonably detailed level within the specified budget and still get sufficiently accurate results. There are often many details to consider. Appearance of furniture and equipment, different number of people staying on the premises at different times.

After all, it takes a lot of computing power and extensive computational resources to perform the simulations and today we have our own data center, in Gothenburg, with the capacity to perform most simulations we need. For even greater needs, there are a number of suppliers with large computer capacity available, for example through cloud solutions.

Regulations vs reality

Regulations are sometimes a blunt tool for describing reality. There are often requirements for air turnover per volume in a room and this is a calculation that most people can do with simpler aids such as Excel. But that calculation says nothing about whether there are places in a room where there is silence. This analysis requires more powerful programs that use, for example, CFDs.

Using CFD, you build a model of the room's air space and simulate how the air moves. The simulation can provide answers as to whether existing or planned changes to the ventilation are correctly dimensioned. However, the design of the regulations means that one often refrains from carrying out the simulations.

Two construction workers on a construction site, wearing vests and security helmets

 In the construction industry, they are far behind other industries when it comes to applying this technology, says Thommy Nilsson. This is despite the fact that buildings are often used for much longer than other constructions and products and there is thus a long-term value. There are a lot of win-wins to gain there.

Martin Kwasniewski - Market Area Manager, Technical Analysis

Martin Kwasniewski

Market Area Manager, Technical Analysis

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Henrik Lysemark - Business Unit Manager, Technical Analysis

Henrik Lysemark

Business Unit Manager, Technical Analysis

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