EXPERIMENTAL STUDY ON THE INFLUENCE OF RIBLETS ON BUS BODY TOWARDS DRAG COEFFICIENT

Abstract

Heavy vehicles such as buses and trucks, generally have a form that is not very aerodynamic, usually
very long and boxy. Aerodynamics can be very influential on the use of fuel when the coefficient of
drag is reduced, the vehicle can be more efficient in their use of fuel because the force that inhibits
will be reduced. One way to reduce this drag force is with riblets. Riblets is a structure shaped like a
bunch of lined trenches. The results of the study on flat plate showed that with the riblets, up to 10%
drag reduction can be achieved with the blade structure compared with only a flat surface under the
same conditions.
Methods to validate the experiments were performed using simulation results with experimental
results from the wind tunnel at a speed of 16-27 m/s. Bus model created by CAD software according
to its original shape to be tested in the wind tunnel and then compare it with the results of the
ANSYS Fluent simulation. Riblets geometry studied using ANSYS Fluent simulation and the
results of the Boundary Layer will be observed as the riblets geometry changes. From the research, it
is known that the best riblets geometry is 1% of the overall length of the bus and with the application
of said geometry, 1.46% drag reduction can be obtained, from Cd 0.548 to 0.54. The model with the
best drag reduction uses riblets on the front roof of the bus.