CFD Based Aerodynamic Analysis

Abstract

Computatoinal Fluid Dynamics (CFD) is a trending branch in the computational and simulation sciences that deals with practical or real-life fluid flows. Aerodynamic analysis, a traditional application of CFD, has been demonstrated in this project. The aim of this project is to understand the modern aero-dynamicity comparison approach, which involves the use of software to replicate the operating conditions of a product, where in the product’s (car, bike, wing, plane, etc.) computer aided (CAD) geometry for simulation is reverse engineered. In this project, thus, the Honda CBR’s (a motor-bike) CAD geometry is obtained from an accurate scaled model with the help of a 3D scanner. Once scanned, a human rider is sculpted; the rider riding the bike in a relaxed stance. The air-flow is simulated over the bike-rider system, the simulation results of which, are compared to a case in which the bike is kept in a similar condition, however, without the rider. Since most real life flows are turbulent, the k-ε turbulence-model has been used to solve for the flow parameters over the bike or the bike-rider system.

Introduction

A CFD problem formulation is based on the mathematical discretization of the Navier- Stoke’s Equations. These equations are solved for the flow parameters (pressure, velocity, etc.) in a defined fluid domain. The fluid domain is discretized using a meshing scheme native to the mesher used by the software. Aerodynamic analysis using requires a geometric profile of the product in a Computer Aided Design format fit for simulation. Since a product’s engineering drawings are a trade secret, it is required that these geometries be obtained using reverse engineering tools such as the 3D Scanner. Once obtained, the fluid domain is meshed, and after applying necessary boundary conditions resembling a product kept in a wind tunnel, the results are validated and interpreted with the experimental/literature-obtained data. Post-processed results can be used to draw important inferences about the model, too.

Figure 3. A Slide Show