Aerodynamic Analysis of the Preliminary Design of SURIAKAR 4 Using CFD Lai Gwo Sung 1,a , Wan Zaidi Wan Omar 1,2,b* , Ahmad Zafri Zainudin 1,c , Shuhaimi Mansor 1,d and Tholudin Mat Lazim 1,e 1 Aerolab, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia. 2 Centre for Electrical Engineering System, Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia. a gslai2@live.utm.my, b,* wanzaidi@fkm.utm.my, c zafri@fkm.utm.my, d shuhaimi@mail.fkm.utm.my, e tholuddin@fkm.utm.my Keywords: Computational Fluid Dynamics (CFD), aerodynamic forces, aerodynamic moments, solar car aerodynamics, energy efficiency, solar power. Abstract A four-wheel solar car, the SURIAKAR 4, was designed based on the revised regulations for the Challenger Class World Solar Challenge (2013). It is a four-wheel car with the front and back wheels on each enclosed in a wind cheating cover. The cockpit is sited in such a way that it sits between the front and rear wheel within the wheel cover on the right side of the car. This paper investigates the aerodynamic characteristics of the car, especially the drag and lift forces, and other forces and moments that determine the stability of the car using CFD package ANSYS Fluent. The model analysis was done with 2.23 million elements after a thorough grid independence study was conducted. At the design speed, the drag coefficient of SURIAKAR 4 is 0.18173 with a frontal area of 0.89342 m 2 and 2131 of power is required to overcome this aerodynamic drag. It was also found that the rolling moment is significant when angle of attack of -8°. Hence, SURIAKAR 4 require 99 kg to maintain its stability. The results also showed the airflow quality around the car, and points where turbulent flow occurred were identified. This flow incurs drag penalty to the car and thus have to be modified. The results of this preliminary study will become the basis for the subsequent development of the new solar car. 1.0 Introduction World Solar Challenge (WSC) is a competition that encourage researchers to develop technologies related to energy generation from solar and energy management in a vehicle. Thus they are to explore the boundaries of sun-powered vehicle or solar car [1]. In 2013, WSC organizer revised the competition’s regulations so that the solar powered cars entering the competition would be more readily realized into future general transport system. This leads to the design and development of the new SURIAKAR 4 that would fulfil the new competition regulations. The aerodynamic design of a solar powered car plays a crucial role since the aerodynamics drag consumes the major power at high speed. The proposed shape of SURIAKAR 4 design is shown on Figure 1. Its body has a symmetric aerofoil section, to reduce the drag force to lowest possible value. The wheel enclosure covers the front and rear wheels on each side, with the driver seat located within the right-side wheel cover between the front and the rear wheels. Another important consideration is the behaviour of the car in cross wind condition. According to the revised regulations, the changes of SURIAKAR 4 from previous version are: i. The driver’s seat position is changed from prone to seating position. ii. The maximum dimension of the vehicle is revised so that it must be no more than 4500 mm in length, no more than 1800 mm in width and no more than 1800 mm in height.