If you drive your car through heavy rain, the car wash or a deep puddle, it goes without saying that the vehicle stays nice and dry. However: In order for this to be a matter of course, the manufacturers have put a lot of effort into developing a vehicle model. Seals on doors and windows must be designed accordingly. Covers on the underbody and engine compartment must be designed and fastened in such a way that they do not become deformed or come loose. And then there’s the air conditioning, which inevitably needs air intakes. These openings must also be designed in such a way that no water can penetrate. The vehicle manufacturers summarize all these requirements under the term “water management”.
“For a long time, water management was heavily dependent on real tests,” reports Monika Wierse. “That has only changed for us in recent years thanks to suitable simulations.” The mathematician heads the Methods & Model-based System Engineering department at Porsche. In this function, she plays a key role in ensuring that issues such as water management can be processed on digital models using computers – without a real drop of rain falling.
Detailed image of the car
The model in the computer represents a detailed image of the real vehicle. Only in the interior you can save a lot, for example the seats. In the simulations, the model is then virtually sprinkled or exposed to heavy rain. It has to drive through water that is up to half a meter deep. It drives quickly through the rain to see the impacting water droplets move backwards along the body. All of this is just part of the water-related issues that the engineering teams at Porsche are working on with simulations.
Even pre-painting in production, in which the bodies are passed through huge immersion baths, can be simulated. This is because the protective layers that have to be applied to the body are in the form of an aqueous solution. Only the intention is different. While rainwater should not later penetrate into the vehicle, it is exactly the opposite in the immersion baths: the coating itself should reach the furthest corners of the body.
“Water management is so computationally intensive that Porsche cannot simulate it on its own systems,” states Wierse. It would simply be uneconomical for the company to have such enormous computing capacities. “Rather, we access the HLRS systems for this,” says the Porsche division manager. The Stuttgart-based automobile manufacturer is one of the pioneering companies that has been using HLRS for simulations since the mid-1990s. Overall, industrial users account for around ten percent of the computer utilization at the HLRS. While there were 25 companies a year in 2017, the number rose to 61 by 2021.
Benefits for everyone involved
Not only the companies, but also the HLRS benefits from this cooperation between the academic and the industrial world. This is because it can further develop its expertise in the field of supercomputing in order to apply it to real-world computer-controlled engineering problems.
The automotive industry is one of the main users of the HLRS. When developing a new vehicle model, prototypes are a tried and tested means of getting as realistic a picture as possible at an early stage. It used to be inevitable to build numerous physical prototypes of a new vehicle before going into production. But such a prototype can only be built when its individual components have already been extensively specified and are also available as prototypes. Therefore, physical prototypes are always available late. That’s expensive and time-consuming. If there are still fundamental problems, it makes things even more complicated.
“We have the strategic requirement in the company to develop with as few physical prototypes as possible,” says Monika Wierse. “When we developed our first purely electrically powered model, the Taycan, a few years ago, it had already driven around the Nürburgring’s Nordschleife umpteen times before there was a real prototype.” For example, it was possible to assess very early on how the cooling circuit would work had to be designed for high-voltage batteries and electric motors in order to meet all driving requirements – including extreme ones. With simulations, the best possible solution can be found even for conflicting requirements.
Aerodynamics, acoustics and crash
The automotive industry has its own powerful computers for simpler simulations. But a number of tasks can only be processed with supercomputers like those at HLRS. In addition to water management, this also includes simulations in the areas of aerodynamics, aeroacoustics and crashes. It is well known that aerodynamics have a significant influence on fuel consumption, but also on handling and driving comfort. In the case of aeroacoustics, for example, the question is how the air flow changes when the sunroof is open in the interior of the vehicle. And virtual crash tests are of course much cheaper than real ones. “With such virtual crash tests, we now achieve a resolution in the millimeter range and can use this to assess, for example, whether a glued seam will tear or a spot weld will hold,” says Wierse, explaining the current possibilities.