3B: Aerodynamic improvements of conventional and double trailers

This project will explore the potential gains from aerodynamic improvements to trailer design. A particular focus is the exploration of improved underbody profiles to minimise aerodynamic drag utilising a novel approach – the use of a water tow tank for road vehicle aerodynamics.


(i) Identify major drag contributions of current semi- and double trailer designs.
(ii) Demonstrate the advantages of tow-tank experiments for vehicle underbody aerodynamics research.
(iii) Quantify underbody drag contribution and identify problem areas.
(iv) Develop geometric flow control solutions to reduce system and underbody drag
(v) Quantify overall drag reduction in demonstrator tests.

Programme, Methodology and Deliverables

Project Tasks

Task 3B1: Compare aerodynamic performance of conventional and novel semi-trailer configurations by i) Designing and building baseline wind tunnel models and ii) conducting baseline testing to determine drag and problem areas.

Task 3B2: Identify potential avenues for drag reduction through literature review and consultation with partners. In this process include practical and operational considerations.

Task 3B2: Evaluate underbody flow.  This will entail i) Designing and building underbody models for tow-tank testing, ii) Analysing the flowfield and identifying critical regions, iii) developing and testing novel flow control devices and iv) evaluating drag savings.

Task 3B3: Explore the potential for modifying the tractor-trailer gap.  We will begin with parametric studies on trailer gap flow, to evaluate how flow control devices might be used, and what drag savings they might give.  Demonstrator design and testing could provide validation of the results and provide a mechanism for disseminating results and future potential.


The work will result in:

(i) a literature survey and new wind tunnel data for trailer aerodynamic drag identifying key contributions, communicated through dialogue with industrial partners to ensure optimum usefulness,
(ii) quantitative data on key drag components to single and double deck trailers as identified from literature,
(iii) a new test facility for underbody flow investigations
(iv) identification and quantification of key drag contributions on the underbody, and
(v) potential for novel geometric modifications to improve underbody drag on trailers.


Click here to read a case study about the aerodynamic improvements made to Waitrose refrigerated vehicles


Academic impact: This project will provide improved understanding of road haulage vehicle aerodynamics, including double trailer layouts and provide improved methodologies for road vehicle testing.  Both the findings and the methodologies will be applicable to other road vehicles and to rail applications.  We will also make a point of disseminating results to those interested in high speed rail.  We will also incorporate research findings in undergraduate education.

Commercial and social impact: The implementation of successful and novel flow control devices would be commercially significant to industrial partners adopting our findings.  Incorporating insights from the work into vehicle design would enhance the competitiveness of UK manufacturers.