Flow laminarisation and drag reduction


Funded by Department of Mechanical Engineering Studentship, 2020-2024

PhD student: Stephen Jackson. Supervisor: Prof. Shuisheng He

Aerodynamic optimisation is of paramount importance in improving the design of aircrafts, automobiles as well as turbomachinery to reduce energy consumption and improve energy production efficiency. Recently it has been demonstrated numerically by researchers at University of Sheffield [1] and experimentally by other research groups [2] that a turbulent flow may be partially or fully laminarised through manipulation of its velocity profile, leading to significant drag reduction. This project is aimed at advancing this theory to better understand the flow laminarisation mechanisms and exploring a number of flow configurations to achieve effective flow laminarisation and drag reduction with minimal effort. The research will be carried out using advanced CFD, namely, direct numerical simulations (DNS) using an in-house code base CHAPSim and making use of high performance computing (HPC) facilities. It is planned that experiments may also be carried out using an existing test facility to verify and extend the numerical results. The test facility is equipped with advanced instrumentation including particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) for velocity measurement and flush mount hot film anemometry for wall shear measurement.

Radial profiles of turbulent shear stress in buoyancy-opposed flows
Radial profiles of turbulent shear stress in buoyancy-opposed flows

He et al. [1] introduces a new framework for characterising the effect of body forces acting in the same direction as the main flow. Initial work in this project is to consider the case with body forces acting against the main flow direction, aiming to get an overview of the changes in turbulence characteristics. Then going on to explain the behaviour using the new framework, and verifying against DNS cases.

Visualisation of turbulent vortexes in buoyancy-opposed flows
Visualisation of turbulent vortexes in buoyancy-opposed flows

1. S. He, K. He, and M. Seddighi. Laminarisation of flow at low Reynolds number due to streamwise body force. Journal of Fluid Mechanics, 809:31–71, 2016.

2. Jakob K ̈uhnen, Baofang Song, Davide Scarselli, Nazmi Burak Budanur, Michael Riedl, Ashley P. Willis,  Marc Avila,  and Bj ̈orn Hof. Destabilizing turbulence in pipe flow. Nature Physics, 14(4):386–390, 2018.

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