Comprehensive CFD Aerodynamic Simulation of a Sport Motorcycle

Abstract

Nowadays, aerodynamics is a key focal point in the vehicle design process. Beyond its direct impact on the performance of a vehicle, it also has significant effects on economics and safety. In the last decade numerical methods, mainly Computational Fluid Dynamics (CFD), have established themselves as a reliable tool that assists in the design process and complements classical tunnel tests. However, questions remain about the possible obtained accuracy, best practices and applied turbulence models. In this paper, we present a comprehensive study of motorcycle aerodynamics using CFD methods which, compared to the most common car aerodynamics analysis, has many specific features. The motorcycle, along with its rider, constitutes a shape with very complex aerodynamic properties. A detailed insight into the flow features is presented with detailed commentary. The front fairing, the front wheel and its suspension were identified as the main contributors to the aerodynamic drag of the motorcycle and its rider. The influence of rider position was also studied and identified as one of the most important elements when considering motorcycle aerodynamics. An extensive turbulence models study was performed to evaluate the accuracy of the most common Reynolds-averaged Navier–Stokes models and novel hybrid models, such as the Scale Adaptive Simulation and the Delayed Detached Eddy Simulation. Similar values of drag coefficients were obtained for different turbulence models with noticeable differences found for k−ϵ models. It was also observed that near-wall treatment affects the flow behaviour near the wheels and windshield but has no impact on the global aerodynamic parameters. In the summary, a discussion about the obtained results was set forth and a number of questions related to specifics of motorcycle CFD simulations were addressed.

Unsteady Subsonic/Supersonic Flow Simulations in 3D Unstructured Grids over an Acoustic Cavity

“…To our knowledge, most of the numerical fluid dynamics applications of the SAS turbulence model has been performed in incompressible flows and over structured meshes and relatively simple geometries [21][22][23][24]; whereas, only few studies have focused on unstructured meshes [25][26][27]. With the purpose to fill that research gap, the Menter SST-SAS model is tested in complex geometries via unstructured grids for the subsonic-supersonic flow regime, then validated with experimental data for the M219 acoustic cavity [14].…”

Aerodynamic Study of MotoGP Motorcycle Flow Redirectors

“…A specific field of aerodynamic research is focused on the analysis and performance improvement of sport motorcycles or superbikes. For example, general aerodynamic studies of a racing motorcycle have been carried out by Winski and Piechna [15] and Palanivendhan et al [16] The work of Winski and Piechna was performed within the MotoStudent university competition, in which students use their analytical skills to conceptualise the motorcycle design and riding experience, as outlined in one study [17]. They focused on a motorcycle in a completely straight position and used several turbulence models, obtaining very accurate results for both the k-ω and S-A model (Spalart-Allmaras) [4,5].…”

Effect of Rider Position on the Energy Consumption of an Electric Motorcycle

“…Although there has been a significant amount of study undertaken around motorcycle aerodynamics [3,4], these are largely focused on the fundamentals of motorcycle design (bodywork, windshield) or performance improvement in a computational environment [5,6]. In the previous studies, the motorcycle and rider are not considered together while evaluating aerodynamics, and the fundamental output of improving aerodynamic behaviour in commercially available vehicles are not evaluated.…”