The study of thin fluid layers is an integral part of many flow problems, ranging from gear lubrication and cleaning simulations, through automotive water management and spray coating. While specialized thin film solvers have been studied for several decades, existing models are typically based on evolution equations that assume the presence of a fully developed thin film in the entire domain of interest. These methods are usually unable to simulate the formation of the thin film itself or the evolution of free moving boundaries within the film. This limits potential applications of the film flow models.&nbsp;In this talk, we will introduce different film models and discuss their limitations which motivate the present work. To overcome these issues, we then propose a particle-based thin film model that tracks the movement of individual fluid droplets. This enables us to predict not just the evolution of an existing film, but also the formation, collapse and break up of a liquid film. Unlike many existing thin film models, the proposed method can simulate flow of thin fluid sheets on arbitrarily curved and moving surfaces. The film thickness or height is built up based on the agglomeration of droplets. We will discuss the applicability of different methods for this height reconstruction.&nbsp;Each fluid droplet being tracked is represented by a single moving particle. The curved surface over which the particles move can be composed either of particles in a meshfree setting, or be given as a surface mesh. We will present both the validation and verification of the proposed thin film flow model. We verify our numerical method against manufactured solutions, and validate the model by comparing results against other thin film models and with finely resolved bulk flow. We then discuss the topic of thin films collecting in corners and edges, which is essential to make these models robust enough to use in actual applications.&nbsp;We also present the application of our method on automotive applications, carried out with industry collaborations. Rainwater falling on a car often forms thin water films on the car surface. Predicting and controlling the behaviour of these fluid films flowing on a vehicle has become essential while considering vehicular design. Accurate modelling of flow paths around vehicles is required for various safety concerns ranging from preventing contamination of windshields and rear-view mirrors to the prevention of water entering critical regions. With the push towards autonomous driving, these thin film flow models become all the more relevant to predict film flow and the collection area of rain water to ensure the correct functioning of exterior automotive sensors.

Thin Film Flow Modelling and Automotive Applications

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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