The document summarizes a study that tested six aerodynamic modifications to a pickup truck bed to reduce drag. A team of students conducted computational fluid dynamics (CFD) simulations and wind tunnel tests to analyze drag on a baseline truck and trucks with different bed modifications. Modifications that fully covered the bed reduced drag the most, while open bed designs increased drag. One modification was able to reduce drag by an average of 10% at all speeds tested. CFD results matched wind tunnel data, validating the analyses. The team identified ways to improve future tests and additional modifications that could further reduce drag.

1. Test Setup
Truck Bed Drag Reduction
Jason Wilke, Jason Carr, Brett Navratil, Ryan Deyhle, Nathan Morgan and Eric Reynolds
Advisors: Dr. Clifford Whitfield, Jacob Allenstein and Rodolfo Manotas Ramos
Introduction
Experimental Results
Computational Fluid Dynamics Analysis Experimental Analysis
Acknowledgements
The Ohio State University and The College of Engineering
AAE 4510/4511 Senior Engineering Capstone Class
Dr. Clifford Whitfield, Jacob Allenstein (Advisor), Rodolfo Manotas Ramos
The Ohio State University: Department of Mechanical and Aerospace Engineering
Hypothesis
Design an aerodynamic modification for the bed of a pickup
truck that will reduce the drag coefficient by 10 percent
while retaining cargo capacity.
Modifications
Modification 1 Modification 2
Modification 3 Modification 4
Modification 5 Modification 6
The modifications that completely covered the bed reduced
drag the most, while the modifications that left the bed open
increased drag (in some cases a substantial amount). Only
modification 1 was able to reduce drag by an average of 10
percent for all speeds. As shown in the figure below, the
experimental and computational results show the same
trends, indicating successful validation of the Fluent and
wind tunnel analyses.
Meshing
Baseline
Modification 1
Modification 6
Modification 4
Modification 5
Modification 3
Modification 2
The figure above shows the experimental drag value at
each speed and with each modification. It can be seen that
drag increases exponentially with the velocity, which the
team used as an initial confirmation of the results, as drag
increases exponentially with velocity. The graph below
shows the coefficient of drag averaged over every velocity,
with the baseline marked as a dashed line.
After flow visualizations were created with Fluent, several
changes to the modification could be made in the future.
Removing or opening the tailgate could positively affect
the open bed designs. Reducing drag could also be
possible by changing angles on the closed bed
modifications.
Future testing in the wind tunnel could also be improved.
The sting could have a variable mounting location to align
with the center of gravity of the truck with the modification
attached. This would provide more accurate results by
measuring the forces on the exact center of gravity.
Future Work
Conclusion
New pickup truck designs improve fuel efficiency with body
modifications, and while improvements are regular they are
relatively small. Many of these improvements focus on
reducing the drag force on the truck. A reduction of drag
directly correlates with an improvement in fuel efficiency.
Recent models of trucks concentrate on modifying the
mirrors and the side skirts of the truck while neglecting the
bed, one of the most important areas for drag reduction.
Bed alterations are typically avoided because many of the
current alterations reduce the functionality of the truck and
do not allow the owner access to the bed or the ability to
haul large objects. If the modification to the truck bed was
easy to install and operate while retaining most of the area
for hauling objects, consumers may consider adding a
modification to their truck. The result would be an increase
in fuel economy of the vehicle while still allowing the bed of
the truck to be used as intended.
Analysis was conducted using ANSYS Fluent to calculate
the coefficient of drag for the baseline model and each
modification.
The model truck was tested in the wind tunnel and drag
force was calculated for the baseline model and each
modification.
The figures above depict the streamlines over the baseline
and modifications at 65 mph, colored by velocity. The dark
blue streamlines showcase where there are low pressure
areas, which increase the drag on the truck. The graph
below shows the coefficient of drag for the baseline and each
modification, as well as the percent difference from the
baseline.