Recent Advances in Wake Dynamics and Active Drag Reduction of Simple Automotive Bodies

Abstract

This is a compendium of recent progresses in the development of wake dynamics and active drag reduction (DR) of threedimensional (3D) simple automotive models, largely focused on the generic Ahmed body. It covers our new understanding of involved instabilities, predominant frequencies, pressure distribution, and unsteady flow structures in the high (12.5 deg < φ < 30 deg) and lowdrag (φ > 30 deg) bodies and the squareback body (φ = 0 deg), where φ is the rear slant angle of the body. Various DR methods and their performances are reviewed, including open and closedloop controls along with machinelearning control (MLC). The involving DR mechanisms, net saving, and efficiencies are discussed. Comments are made for the areas that deserve more attention and future investigation.