Article in cooperation with Dr. Johannes Eben, Head of Technology, BORA
The kitchen has become a central hub for families and for entertaining in modern homes. Kitchen designs and functionality are evolving to accommodate more activities, reflecting a shift from practical to versatile living space.
Researchers at the Silestone Institute published a Global Kitchen Study, which found that kitchens today transcend traditional roles by functioning as vibrant centers for various activities, including socializing, working, and dining. Open layouts with comfortable seating and innovative design elements can transform kitchens into inviting social spaces where people enjoy gathering while providing the practical comfort to create delicious snacks and meals.
Willi Bruckbauer, founder of BORA Lüftungstechnik [ventilation technology] GmbH, has significantly influenced modern kitchen design through his novel cooktop extractor systems. Bruckbauer, a master carpenter with over 20 years of experience in the kitchen sector, wanted to make kitchens more attractive.
Bruckbauer sought to find an alternative to the big eyesore in kitchen design: the noisy, visually dominant, or just plain ugly yet vital traditional overhead range ventilation system.
Effective extraction of cooking odors, smoke, and heat is critical for an enjoyable and safe kitchen environment, both for cooks and guests. Bruckbauer’s hands-on craftsmanship and passion for understanding customer needs led BORA to develop an elegantly engineered cooktop-level vapor extraction system with an extremely small footprint—a superior solution, especially compared to traditional stovetop hoods.
The BORA ventilation technology comes in various sizes and functional options. Each creates an area of low pressure that draws in air from the surrounding cooktop. The crossflow suction of a BORA cooktop extracts steam and vapors faster than they rise (at a maximum of 1 meter per second), thus eliminating them. Streamlined and subtle, it eliminates the need for an unsightly overhead extractor, allowing more design freedom in a kitchen space. In addition, sound absorbers further soften its low-noise motors, and its extraction efficacy means 100 percent clean air at head height.
Visualizing Physics in Product Design
Developing a cooktop extractor system capable of tackling cooking vapors and odors at their source (right from the cooktop, before they can spread) required a thorough understanding of the physics involved.
To validate the optimal air flow of the extractor system, Bruckbauer and the BORA engineering team knew performing multiple physical tests would be expensive and take time. For example, the naked eye can’t see pressure, velocity, sound, airflow, and other factors. While such variables can be made visible through experiments such as using visualization paint for evaluating fluid flow through a blunt body or using an acoustic camera to point out noise sources (among other tests), the complexity and costs involved in obtaining the desired results with such methods are incredibly high.
To reduce both the lengthy physical testing process and the associated expense, BORA searched for a digital solution that would enable faster and more efficient optimization of their designs, even at the earliest stages.
Cooktop-level extractor inlets, like traditional overhead hoods, must effectively manage the airflow through the system. Key elements such as inlet size, flow constriction, and blower design are crucial to effective vapor extraction. One of the main challenges lies in the airflow dynamics required to ensure efficient operation from the compact space beneath the cooktop without sacrificing performance.
Discovering the Best Approach
The computational fluid dynamics (CFD) software market is packed with numerous fiercely competitive developers offering various solutions. BORA needed a CFD product with a powerful solver technology that could handle complex modeling, enabling them to run large-scale simulations efficiently and accurately. BORA also needed a cloud-based solution to ensure easy access for all key stakeholders. In addition, they preferred a system that supported high-performance computing on the cloud, which would save the expense of acquiring high-end computers by enabling engineers to conduct CFD studies on the cloud.
BORA’s design engineering team, already happy with Dassault Systèmes’ SOLIDWORKS® 3D mechanical CAD software, considered working with them again to expand their current capabilities. PowerFLOW, a Lattice Boltzmann-based physics solver from SIMULIA, seemed to meet all their criteria for design testing. Still, the BORA management team needed proof that the technology could produce highly precise simulation data for their engineering team.
When BORA participated in an Online Aeroacoustics Workshop hosted by Dassault Systèmes, the capabilities and potential benefits of PowerFLOW intrigued the team. They agreed to a Proof of Concept (PoC) to evaluate PowerFLOW’s efficacy in simulating aeroacoustic behavior compared with their traditional [physical] experimental methods. The PoC aimed to validate simulation data against acoustic measurements previously performed on BORA’s physical testing apparatus, a semi-anechoic chamber equipped with a last-generation microphone array.
Aerodynamic Insights into Flow and Noise Source Generation
Within the PoC, the aeroacoustic behavior of the BORA Professional 3.0 cooktop extractor was analyzed for a single operating point of the system’s centrifugal fan.
A detailed CAD geometry of the production model was prepared with PowerCASE, PowerFLOW’s advanced CAD pre-processing software for complete model build up (Figure 1). All the relevant and geometrically complex details of the cooktop extractor model were kept with no major simplifications. Subsequently, the simulation scenario was defined with the aid of PowerCASE.
The setup of the simulation scenario included the definition of suitable boundary conditions, the modeling of a semi-anechoic chamber environment to resemble BORA’s test rig, as well as all relevant refinement regions and the inclusion of virtual microphone probes to register the sound pressure variation.
The virtual microphones were positioned as on BORA’s original experimental setup. The probe results were generated and analyzed with the aid of PowerACOUSTICS, an acoustic analysis software of the PowerFLOW Simulation Suite. The predicted noise levels displayed a good agreement when compared with BORA’s experimental results. The relevant spectral characteristics of the microphone signals were well predicted for a broad frequency range.
A deeper aerodynamic analysis provided meaningful insights of the flow paths through the cooktop extractor. This analysis highlighted regions of high velocity and vorticity concentration, possibly leading to noise source generation and subsequent propagation (Figure 2).
Advance aeroacoustic post-processing confirmed the presence of dominant noise sources on the blades of the radial blower. Those dominant noise sources are generated as a result of the strong revolving flow entering the radial blower inlet (Figure 3). The graphical deployment of aerodynamic and aeroacoustic results was performed with PowerVIZ, a high-performance CFD visualization tool.
To summarize, the beforementioned outcomes demonstrated PowerFLOW’s ability to accurately predict sound pressure levels across a wide frequency range and provide detailed visual insights into fluid dynamics unobservable through experimental methods.
Seeing is Believing
The successful results of the PoC primarily influenced the decision to adopt PowerFLOW. BORA engineers recognized the software’s capability to enhance their understanding of complex fluid interactions within their products, which traditional experimental approaches could not achieve. The visual insights and detailed data provided by PowerFLOW facilitated a deeper understanding of the acoustic and aerodynamic performance of BORA’s designs.
BORA also utilizes the SIMULIA Cloud, which offers browser-based access to the software. Cloud access facilitates remote work, enabling collaboration via quick and efficient data sharing. It also makes getting support from Dassault Systèmes’ technical team easier because complicated simulation challenges can be shared visually while collaborating with technical support on the 3DEXPERIENCE cloud platform in real time.
The 3DEXPERIENCE cloud platform utilizes up to 1200 core clusters, eliminating the need for BORA to buy high-end workstations and maintain extensive computational resources. SIMULIA cuts costs and accelerates the process, enabling complex simulations to be completed within hours.
BORA has repeatedly expressed the benefits of visually inspecting internal system dynamics with PowerFLOW, which informs their decision-making processes and design improvements. This capability has been instrumental in their latest developments, including aerodynamically optimizing their products solely using PowerFLOW simulations, thereby eliminating the need for physical prototypes. This strategic use of PowerFLOW makes it a critical tool in BORA’s product development strategy, enabling efficient, cost-effective, and collaborative development of new products while minimizing the necessity for physical prototypes.
“SIMULIA helps us to push the efficiency of our products to the limits of what is physically possible.”
-Dr. Johannes Eben, Head of Technology, BORA
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Katie is the Editor of the SIMULIA blog, an expert in engineering and scientific communication, and a strategic digital marketer. Katie has a BA in English and Writing from the University of Rhode Island and a MS in Technical Communication from Northeastern University. She is also a proud SIMULIA advocate, passionate about democratizing simulation for all audiences. Katie is a native Rhode Islander who lives just outside of her favorite city, Providence. She is a true New Englander and loves sharing all the cool things NE has to offer. She enjoys a variety of hobbies including history, astronomy, science/technology, science fiction, true crime, fashion and anything associated with nature and the outdoors. She is also mom to a 5-year old budding engineer and two crazy rescue pups.