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Flow and fluid simulations

Too cold, too stormy and also still quite wet – the weather does not bend to the will of humans.

But what can you do about it? We wouldn't be as tolerant about the climate inside our vehicle. No matter when and where we travel in vehicles, we expect to sit in a comfortable temperature and be surrounded by a light, pleasant breeze. Wouldn’t that be something!

Fortunately, there are people at csi entwicklungstechnik who know how to create the perfect comfort climate in a car. The people in our computing and simulation department.


Welcome to the dark side of the vent.

Massive calculations and analysis take place long before the air flows gently over us through the opened slats of the air vent. More precisely, the simulation team’s work begins before any actual components – air vents or slats – are fitted. Like meteorologists who produce their forecasts from weather models, our simulation experts calculate simulation predictions about pressure losses, flow velocities and flow paths inside a car. They clarify in advance whether the air really arrives where it is meant to, or whether the vents are blasting out a hurricane that would ruin carefully coiffured hairdos.

This is done using CFDs, Computational Flow Dynamics, using OpenFoam software design data. They reveal whether all the specification requirements have been fulfilled or if there are weaknesses and potential for improvement which need to be taken into consideration in the design.

Failures? We make short shrift of them!

Things work best of all when we are commissioned with the design and simulation of a component. We can then use the synergies between design and simulation in networking to reduce the geometrical preparation to a minimum. We do this using the ANSA pre-processor ANSA supplied by BETA. If the words ANSA and BETA or networking and geometry preparation mean nothing to you, don’t worry. This is about – as it basically always is – saving time with intelligent (software) solutions and making the design process as compact as possible. ANSA allows us to carry out multiple processes fully automatically, reducing human involvement and user errors. When the completed calculation model has been built in a network, we then conduct multiple simulation loops in the shortest time to try out all the possible options. This is done with the serious involvement of the programming language Python and generally with Shell scripting within a Linus operating system. To put it simply: we shorten the development process.

Perfection right before your eyes

OK. Theoretically we then rapidly understand the lie of the land and how pressure losses, flow speeds and processes behave. But "theoretically" is not enough for the development of a car and its interior. It is much more about the practicality of manufactured parts. That’s why our calculation and simulation department also look after component optimisation by checking the geometrical construction with an optimisation environment in LS-OPT supplied by Dynamore, that is calculating. The calculation results can be linked to ParaView and reveal the effects of changes and modifications to the designers.

With regard to the slats on the interior vents, this means first defining the optimizsation parameters. The optimisation program LS-OPT determines the best possible geometry that can be used to achieve the defined goal based on these parameters. The geometry here is varied and formed in the ANSA pre-processor using morphing. Each geometrical variation is automatically transferred to a simulation model where it is calculated and the results are analysed to assess the effect of the change(s).

Creating knowledge

Unlike meteorologists, here at csi we can predict and calculate more factors. Thanks to our in-house design expertise, we can often take things into our own hands. That means we can input the knowledge acquired from our simulations directly into the design. Development times are further reduced with the use of the FloEFD tool integrated in CATIA. The "lean" EFD simulations (Engineering Fluid Dynamics) which our designers work with are regularly supplemented by CFD analysis to observe any physical effects that may arise.

A hot topic: batteries

Apart from air flows, multi-phase simulations and stationary or transient heat transfer are some of the major issues the csi calculation team deals with. This is assuming even greater importance due to the growth of electric mobility. Multi-phase simulation is used in the development of cooling plates for battery-powered vehicles etc. Multi-phase simulation is used to analyse whether the cooling cycle is designed in such a way that its geometric form enables it to be fully ventilated in the first filling. At csi we can also examine whether the heat generated by the battery cell packs can be reliably dissipated. The efficiency of the cooling can be evaluated by observing the temperature processes. If the temperature process is largely even, this supports the operational stability of the cooling plate system. You won’t be surprised to learn that our calculation and simulation department also has and uses tools to predict operational stability. After all, this is also ultimately part of ensuring that you don’t suddenly find yourself sitting on a hot seat inside the vehicle, while somebody else has a pleasant breeze wafting around them.


csi entwicklungstechnik | Neckarsulm | Simulation Project Manager

Valerij Schwiderik | Simulation Project Manager

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