Numerical Simulation Research Of Automobile Wading And Water Phase Distribution On The Body Surface Based On VOF Method

With the increase of the per capita consumption level of urban residents, the car is no longer a prohibitive luxury, and gradually become more and more popular and a fashion trend. This trend also allows users to have a higher and higher requirement to the quality of a car. Everyone has a dream of a powerful and beautiful "movable furniture". So in order to enable the customers to have a pleasant driving experience, automobile engineers are increasingly concerned about the cleanliness and comfort of the car’s surface. Therefore, researching the water contaminated area distribution caused by the revolving wheel when the car is wading is a key process during the automotive R&D. It has the most important practical significance.Theoretical analysis, numerical simulation and experimental verification are usually used in relevant researches of computational fluid dynamics. Numerical simulation is convenient, efficient and time-saving which is the advantage compared with theoretical analysis and experimental verification. The experimental conditions, which can’t be controlled in the real road experiment, can be achieved in numerical simulation. Moreover, numerical simulation is able to obtain the precise phase and velocity contour in a short time and capture the flow field structure and phase interface to research polluted area trend.In this paper, the traditional methods of computational fluid dynamics and multiphase flow theory are combined. The article explored a method of numerical simulation of researching the water attachment region on the body side surface caused by the revolving wheel when the automobile is wading. First, 2D dam break model was used to verified the practicability of the method and then established the different wheel tire structure of the spokes and the tread pattern. During the capturing the phase interface distribution and the movement trend with the method of volume of fluid, the unsteady Realizable k-ε model was used. And in order to measure the contaminated area, the image processing software was used to calculate the water pixel area. After the comparison of the several simulations, the accuracy of the numerical simulation method was verified, which lain a good foundation for the following research work.By comparing the phase images of different models and the flow streamline of the tire, we can found that with the spoke structure the water attachment area was relatively small and the number of the spoke less the wading performance is more superior, the probability of water in the body surface attached to the smaller. At the same time, the larger the aperture area, the more turbulence of the airflow behind the tire, the more irregular movement of the water phase, it is easier to adhere to the surface of the car body.Finally, this paper proposed an improved performance of water spray according to the reality conditions when the car is wading driving. A scientific and effective method to optimize the structure of automobile fender was adopted. By making the fender size as the input and the water attachment area for the response, the optimization platform was built with the Isight software. And the process of the optimization design of pneumatic accessories was realized through the establishment of Kriging approximate surrogate model. Then the optimization results are verified by the traditional computational fluid dynamics method, which verifies the reliability of the approximate model and the accuracy of the optimization process. It also lays a theoretical foundation for the follow-up related research.In this paper, a research approach, based on finite volume method, unsteady Realizable k-ε turbulence model and volume of fluid method, was adopted to investigate the pollution distribution caused by wheels water spray when vehicles wading in the water. This approach combined computational fluid dynamics method with multiphase flow theory and revealed the influence of different wheel web plate structures and tread patterns on wheels splashing spray.In addition, pollution reduction solutions were proposed to reduce water phase distribution on auto body surface from the aspect of aerodynamics. This research contributes to automotive external flow field analysis and multiphase flow study. The conclusions can provide theoretical support for aerodynamic accessory designing during automobile research and development, which has definite guiding meaning.