Drag reduction of bluff bodies in tandem: Size and spacing effects on cylinders and cyclists

In cycling, the presence of drag reduction from drafting, when multiple cyclists ride in tandem, is a considerable area of performance enhancement for a cycling team and the customisation of this tandem group has the potential of maximising the drag reduction for the entire group or a specific cyclist. The flow interactions between two tandem...

POD-based surface pressure reconstructions from sparse sensing: An experimental investigation

Aerodynamic load determination through integration of the surface pressure distribution is limited in accuracy by the discrete number of measurements taken. Therefore, typically relatively large numbers of spatially distributed measurements are required which increase setup complexity, latency, cost and weight while requiring physical access in...

Recent advances in understanding the flow over bluff bodies with different geometries at moderate Reynolds numbers

The application of unsteady incompressible flow phenomenon over the bluff bodies has received the attention of many researchers due to the rich and complex physics underpinning these flows, and thus requiring special attention in their modelling and numerical simulations. The wake that forms at the leeside of the bluff body is of particular...

Experimental investigation of cavitation-induced erosion around a surface-mounted bluff body

The objective of this study is to investigate the collapsing behavior of cavitation, which leads to the erosion of material. An experimental examination was conducted in a channel with a semi-circular cylinder obstacle, which serves as a “vortex cavity” generator. Cavitation was achieved by employing a range of pressure differences over the...

Experimental and numerical study of cavitating flow around a surface mounted semi-circular cylinder

In this paper, the cavitating flow around a bluff body is studied both experimentally and numerically. The bluff body has a finite length with semi-circular cross section and is mounted on a surface in the throat of a converging-diverging channel. This set-up creates various 3D flow structures around the body, from cavitation inception to...

The influence of underhood flow on bluff road vehicles in a platooning configuration: A numerical study

The transport sector is making a significant contribution to the global CO2 emissions causing Global Warming. A large portion of this is caused by heavy-duty vehicles like tractor semi-trailer combinations. Since tractor semi-trailer combinations are often operated at relatively high speeds for long periods of time their fuel consumption, and...

The Flow Topology of the Ahmed Body in Cross-Wind: An Experimental Investigation by means of Robotic Volumetric PIV

The near wake of the Ahmed reference body in the presence of steady cross-wind is investigated experimentally by means of large-scale three-dimensional Particle Image Velocimetry (PIV). A novel experimental technique is employed which exploits coaxial imaging and illumination while relying on Helium Filled Soap Bubble (HFSB) seeding as well as...

Flow analysis between two bluff bodies in a close distance platooning configuration: A Numerical and Experimental Study

In the European Union greenhouse gas emissions of heavy duty vehicles make up 30% of the total caused by road transport. By placing vehicles in a platoon configuration the aerodynamic drag can be heavily reduced. The effect of platooning has been studied on both American and European type vehicles. However many of these studies only disclose the...

Base Drag Reduction of Heavy Duty Vehicles by Combining a Tail and Guide Vanes: A Numerical and Experimental Analysis

To limit the threat posed by global climate change it is vital to reduce the emissions of the transport sector in the short term. Two existing aerodynamic add-on devices for the rear-end of a heavy duty vehicle, a tail and guide vanes, are combined in an attempt to achieve a larger drag reduction. A research is performed using numerical...

The effect of geometry on the surface waves generated by vertical surface-piercing cylinders with a horizontal velocity

Air-Wake Flow Dynamics on a Simplified Frigate Shape: An Experimental Study by Large-Scale Tomographic PTV

: The Air-Wake produced by a ship superstructure is a complex, highly turbulent and unsteady three-dimensional flow, which contains large flow features that interact with the helicopter rotor during critical take-off and landing procedures. An international research effort (TTCP, AER-TP2) which involves experimental and numerical studies on...

Aerodynamic Analysis of Drag Reduction Devices for the Tractor-Trailer Gap

Aerodynamic analysis of a platoon of bluff bodies subjected to cross wind, a numerical investigation on the effect of drag reduction devices

Due to the awareness of climate change, more sustainable and efficient ways of transport are needed. The most polluting road transport mode in the European Union are the long-haul tractor-trailer combinations. This study will investigate the aerodynamic characteristics of three vehicles in a platoon subjected to cross wind conditions. The effect...

Investigating Step Cylinder Wake Topology with Tomographic PIV

Step cylinders have numerous applications, for instance, radio communication towers, airport control-towers, antenna members, etc. Numerous applications motivate researchers to investigate this bluff body both numerically and experimentally. The single step cylinder model is comprised of a small-diameter cylinder (d) attached coaxially to a...

Design of Low Drag Bluff Road Vehicles

Low drag bluff road vehicle design can be obtained effectively and efficiently with a three phase approach that uses numerical simulations, scaled wind tunnel experiments and full-scale road testing. By applying this generalised method, SideWings were developed for an improved trailer underbody flow and tails for the trailer's rear-end. A...

Joint Scalar versus Joint Velocity-Scalar PDF Simulations of Bluff-Body Stabilized Flames with REDIM

Two transported PDF strategies, joint velocity-scalar PDF (JVSPDF) and joint scalar PDF (JSPDF), are investigated for bluff-body stabilized jet-type turbulent diffusion flames with a variable degree of turbulence–chemistry interaction. Chemistry is modeled by means of the novel reaction-diffusion manifold (REDIM) technique. A detailed chemistry...

A study of grid convergence issues for the simulation of the massively separated flow around a stalled airfoil using DES and related methods

A systematic grid convergence study is conducted for the Detached-Eddy Simulation (DES) of the massively separated flow around a NACA0021 airfoil at high angle of attack. In order to study the convergence characteristics of DES/LES problems, velocity fields using a series of grids must be generated that demonstrate sufficient dynamic similarity...

Experimental analysis of the flow around a cylinder with a square cross-section

The present work investigates the flow around a two-dimensional square section object at varying angles of incidence. The experimental approach employs Particle Image Velocimetry for the determination of the time-averaged velocity field and the unsteady large scale coherent variations (e.g. vortex shedding) as well as turbulent fluctuations. The...