Abstract
A method of automatic recognition of the reversed flow region in a digitalized path-line picture has been proposed. Flow direction is locally determined by calculating the vorticity at an average position among four neighboring pathlines in four different ways. The input image needed in this method is only one path-line picture taken with standard camera equipment. In order to examine the accuracy, this method is applied to determine the flow directions in a separated flow around a circular cylinder, using the velocity distribution obtained numerically by the MAC method. It is found that only 2% error occurs in this case. As an application of the method to a flow visualization picture, a reversed flow region in a square cavity is recognized by the method, and the result is in good agreement with that of other experimental methods.
