Study on the effect of dimple position on drag reduction of high-speed maglev train

Transient numerical simulations were carried out by placing dimples at the top, sides and bottoms of the tail car streamline area of a high-speed maglev train. The results of an improved delayed detached eddy simulation turbulence model using three-dimensional compressible Navier-Stokes and shear-stress transport K-Omega double equations were compared to the results of a wind tunnel test to verify the numerical simulation accuracy, within 5% of the ground truth, which is an acceptable precision range. The results show that dimples arranged on the streamline area atop the train tail car affected the locations at which the airflow at the top and bottom of the train met and weakened the strength of the wake. The aerodynamic drag and lift coefficient decreased by 3.40% and 4.27%, respectively. When the dimples were arranged on the streamline area at the sides or bottoms of the train tail car, they had little effect on the top of the tail car, so they did not destroy the balance of the airflow at the top and bottom. They also had little influence on the development of wake topology. Therefore, the aerodynamic drag and lift of the train changed little.