Establish appropriate fluid domain and flow parameters and consider one or more of the following aspects: 1. The front and rear shape of the vehicle

Handbook 4. 1CWK50 The Brief

The Brief

You are working as the Technical Engineering Advisor for a large DIY store. The payload of the vehicle is required to take 62 pallets of mixed palletised goods for delivery in the UK only. Goods are stored in central England at Coventry and the whole of UK is stocked from this hub. You are required to analyse the current vehicle specification to produce a vehicle body system that is aerodynamically optimised for both outward and the return journey. Use the provided CAD file and manufacturer`s specification to establish your baseline models and progress your simulations.

In your investigations, you should use the following assumptions:

1. No cross flow velocity component
2. Yaw angle is zero
3. Maximum legal speed 90kph
4. The simulation can be assumed to be steady-state i.e. no acceleration
5. Standard temperature and pressure conditions are considered for ambient atmosphere
6. The fluid is dry air zero moisture Note: If you make any other assumptions in your calculations please ensure you state these at the start of each calculation

Determine: Establish appropriate fluid domain and flow parameters and consider one or more of the following aspects:

1. The front and rear shape of the vehicle
2. The prime driver compartment and its interaction with the vehicle load
3. Any other aero aid devices that can be fitted that do not affect the legal compliance or load carrying capabilities of the combination
4. Any other modification that could be made to the outfit Values for the lift and drag should be calculated using different Reynolds numbers and appropriate analysis.

Evaluate:

Your aim is to create an aerodynamically optimised body system for both outward and return journeys performance, thus: reducing fuel consumption minimising the vehicle`s environmental impact reducing the overall operating cost.

Sample Answer

Aerodynamic Optimisation of a Pallet Delivery Vehicle for UK Distribution

1. Introduction

This report has been prepared for a large UK DIY store. It focuses on designing an improved aerodynamic vehicle body to carry 62 pallets of goods from a central hub in Coventry to various UK locations. The aim is to reduce fuel use, cut environmental impact, and lower operating costs for both outward and return journeys.

2. Project Overview and Assumptions

To begin, we make these key assumptions for our aerodynamic analysis:

• No crosswind during the journey

• Yaw angle (vehicle’s rotation side-to-side) is zero

• Maximum speed is 90 kph (UK legal limit)

• Steady-state simulation (no acceleration)

• Standard air temperature and pressure

• Dry air only (no moisture in the air)

• Pallets remain unchanged during travel

• Return journey is empty or lightly loaded

We will use the given CAD files and manufacturer specs to build a base model for simulations.

3. Simulation Setup

• Fluid domain: Air around the truck

• Flow parameters: Inlet velocity = 90 kph, outlet at ambient pressure

• Reynolds number variation: Based on vehicle length and airflow speed, tested at several speeds

• Software used: CFD tool like ANSYS Fluent (assumed)

4. Aerodynamic Factors Considered

4.1 Front and Rear Design

• Current design: Flat nose and vertical rear increase drag

• Proposed improvements:

  • Smoother, rounded front to reduce air resistance

  • Rear-end taper or boat tail to lower pressure drag

  • Trailer gap fairing to smooth air between cab and trailer

4.2 Driver Cabin and Load Interaction

• Add roof deflector on cab to direct air over the trailer

• Use side skirts on the trailer to stop air from flowing underneath

• Check alignment between cab and trailer for minimal airflow disruption

4.3 Aero Devices (Legally Compliant)

• Side skirts (reduce underbody drag)

• Boat tail rear flaps (cut rear turbulence)

• Wheel covers (smooth airflow over wheels)

• Fairings for fuel tanks or axles

• Tyre pressure monitoring for rolling resistance

All devices will be checked against UK legal height, width, and length regulations.