Abstract
The paper introduced the research of laser-sheet technology and laser-Doppler-Velocity-Meter to study the streamline of three-dimensional separating flow of domestic cars wake and to measure the distribution of velocity .The experiment results show that it is effective, combining the method of laser flow visualization and the digital image technology, to reveal the structure of cars wake and determine the resource of drag. This paper provides the foundation to establish the theoretical model of dynamics simulation of three-dimensional separating flow of domestic car.