Numerical Modeling of the Shape Optimization for a Commercial Car by Decreasing Drag and Increasing Stability

The aerodynamic understanding of the automobile has become very significant for the automotive industry to decrease fuel consumption. The aerodynamics of vehicles influences fuel consumption, stability, cooling, safety, and environmental pollution. As the shape of the vehicle plays an important role in automobile aerodynamics, it is desired to optimize it for better performance. For optimization, the simulations are run for the varying parameters of system design. Automobile aerodynamics depends on a large number of parameters. Even if some key parameters are selected, still there are very large numbers of aerodynamic parameters that need to be considered for which a smart optimization tool is required. A Fluent Adjoint solver has been used for aerodynamics optimization in this study. This tool directly identifies the most sensitive parameters and modifies the geometry to achieve desired changes in the observables, i.e., drag and lift. Additionally, it results in optimal design in a minimum number of simulations. In the current study, the aerodynamic investigation was performed for a commercial car, including shape optimization for reducing drag and increasing its stability (negative lift). The drag and lift coefficients of the car were computed using the ANSYS Fluent. After the conventional flow simulation, an Adjoint solver was used to determine its shape sensitivity concerning observables i.e., drag and lift. Based on that sensitivity data, the shape was modified using a mesh morphing operation. The modified car was again analyzed and a significant improvement was observed in its aerodynamics. There was a decrease of 0.02, about 6% in the drag coefficient, and an increase of 0.05, about 24% in the negative lift coefficient.