ANALISA DESAIN AERODINAMIKA MOBIL SEDAN DENGAN MENGGUNAKAN PROGRAM KOMPUTASI DINAMIKA FLUIDA

Abstract

Computational Fluid Dynamic (CFD) simulation was used to calculate drag coefficient (Cd) sedan model, Honda Civic 2006. The simulation processes consist of three steps; those are pre-processor, solving, post processor. Pre-processor consists of modelling using CATIA V5R6 and mesh generation using Gambit 2.3.16. Next step is solving using FLUENT 6.2.16. First, simulation is conducted by employing k-epsilon and k-omega turbulence models to calculate the drag coefficient, and then the result is compared to the drag coefficient released by Honda. From seven models applied in this simulation k-omega SST is selected as turbulence model for the next simulation process because of its smallest errors value that is 1.939 %. Post processing process is presenting to present the simulation result done by FLUENT. The next simulation is done on various speeds that result the various Reynolds numbers. The relation between the various Reynolds numbers to drag coefficient is obtained where the curve formed has the same trend to that of the experiment from the reference. The next case is simulation of ground wall supposed as road, where road is assumed to be stationary or moving wall parallel to fluid speed. The difference of drag coefficient within 0.02 is obtained. The last cases are to study the effect of spoiler on the model. With the various angle of 5°, 10°, and 15°, the result confirms the usage of spoiler increases drag coefficient value. The biggest drag coefficient value is on spoiler angle of 15 ° that is 0.429. Thus, the function of spoiler is increasing the compressive force downwards for model on the chance of stability model on high speed.