A method for determining a velocity of a flowing fluid includes estimating a Reynolds number for the flowing fluid; comparing the estimated Reynolds number with a selected range; and determining the velocity of the flowing fluid based on a flow model selected from a laminar flow model, a turbulent flow model, and a partial laminar flow model. An ultrasonic flow meter includes a plurality pairs of transducers configured to form a plurality of measurement paths in a pipe, wherein the plurality of measurement paths are arranged asymmetrically relative to a centerline of the pipe.