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Proposing Institution

Institut für Automobilaerodynamik, TUM
Project Manager

Daiki Matsumoto
Boltzmannstr. 15
85748 Garching
Abstract
The recent growth of available computational resources has enabled the automotive industry to utilize unsteady Computational Fluid Dynamics (CFD) for their product development on a regular basis. Over the past years, it has been confirmed that unsteady CFD can accurately simulate the transient flow field around complex geometries. Concerning the aerodynamic properties of road vehicles, the detailed analysis of the transient flow field can help to improve the driving stability. Until now, however, there haven’t been many investigations that successfully identified a specific transient phenomenon from a simulated flow field causing poor driving stability. This is because the unsteady flow field around a vehicle consists of various time and length scales and is therefore too complex to be analyzed with the same strategies as for steady state results. Dynamic Mode Decomposition (DMD) extracts the coherent structures from complex, transient flow fields, which can help to identify certain target phenomena. However, one issue in the practical application of DMD is the difficulty to find a connection between a computed mode and an actual aerodynamic effect on the body. To overcome this issue, one goal of this work is to develop an extension of existing DMD algorithms that enables the interpretation of DMD modes such that they can be connected to the aerodynamic design.Another issue is that conventional DMD algorithms require massive storage space and RAM (up to several TB per case), because all the snapshots of the unsteady flow field must be loaded into the RAM at once. This behavior must be improved to enable the practical application of DMD, since industry usually does not have access to computers with such a large amount of RAM. Therefore, another goal of this work is to optimize an incremental algorithm of DMD for large industrial cases, which results in significantly reduced RAM consumption.

Impressum, Conny Wendler