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The University of Southampton
Engineering
Phone:
(023) 8059 2344
Email:
J.M.Lawson@soton.ac.uk

Dr. John M Lawson MA, MEng, PhD

Lecturer

Dr. John M Lawson's photo

John Lawson is a Lecturer in the Aeronautics and Astronautics Department within the Faculty of Engineering and Physical Sciences at the University of Southampton.

John specialises in experimental fluid mechanics, turbulence and particle laden flows. His work unites theory and numerical simulations with the development and application of optical flow diagnostics to explore, quantify and model turbulent flows.

2019-2021: Marie Curie Research Fellow, University of Southampton

2018-2019: Research Fellow, Ganapathisubramani Group, University of Southampton

2015-2018: Postdoctoral Researcher, Bodenschatz Group, Max Planck Institute for Dynamics and Self-Organisation, Germany

2011-2015: PhD in Engineering, “A scanning PIV study of homogeneous turbulence at the dissipation scale”, University of Cambridge, UK

2007-2011: MEng (Hons.) in Engineering, University of Cambridge, UK

Research interests

  • Turbulent flows
  • Particle laden flows
  • Mass transfer
  • Fine scale turbulence
  • Optical diagnostics development (e.g. 3D particle tracking and PIV, LIF)

Resolving Effects of particle Shape and Inertia in Scalar Transport (RESIST)

When small, rigid particles are immersed in a turbulent fluid, they tumble, slip, concentrate and re-orientate themselves amidst a chaotic flow.

Resolving Effects of particle Shape and Inertia in Scalar Transport
Resolving Effects of particle Shape and Inertia in Scalar Transport

 

 

 

 

 

 

Simultaneously, material may be transferred from the surface by convection and diffusion. Nature and engineering are filled with examples: planktonic osmotrophs absorb nutrients from turbulent ocean waters, and industrial processes grow crystals in agitated suspension, to name but two. Such particles are rarely ever spherical. Present models overlook this, neglecting the convective transport mechanisms governed by shape and inertia and fail to predict their consequences, for example, in the adaptation strategies of marine organisms.

This project aims to parametrically survey the effects of aspect ratio and inertia in the mass transfer to ellipsoidal particles through a combination of laboratory experiments, numerical simulations and theory. The project has developed and validated inexpensive models for high Péclet number particle-scale mass transfer which account for these factors, providing new avenues for the modelling and simulation of mass transfer from irregular particles.

This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 846648.

Research group

Aerodynamics and Flight Mechanics

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Articles

SESA6070: Experimental Methods for Aerodynamics

FEEG1004: Electrical and Electronics Systems (Tutor)

I advertise a new range of 3rd year Individual Projects and masters level projects each year. Some examples of past and current projects are listed below. If you have an idea for a project, I am happy to discuss supervising it.

Measuring the drag of a wall-mounted body using an integrated photoelastic sensor (IP, 2021-2022)

Drag due to the fluid flow over a vehicle’s body (e.g. a ship’s hull, an aircraft body) substantially depends upon surface roughness. Measuring and predicting the form drag of individual roughness elements and quantifying their contribution towards total skin friction drag remains challenging. Resistive strain-gauge load cells are the dominant technology for measuring aerodynamic loads but are prohibitively expensive to measure the gram-force size loads on several roughness elements.

This project is about developing a new approach to sensing form drag of individual roughness elements using a load cell based on photoelastic strain-gauges, which could be deployed to measure the form drag of arrays of several roughness elements. We have recently developed a prototype load cell based on this technology, shown in figure 1, capable of measuring loads in the tens of gram-force range. This project will extend this work by measuring forces on a wall-mounted body in a wind tunnel by integrating the sensor into the body.

Measuring the drag of a wall-mounted body using an integrated photoelastic sensor
(a)
Measuring the drag of a wall-mounted body using an integrated photoelastic sensor
(b)
Measuring the drag of a wall-mounted body using an integrated photoelastic sensor
(c)

 

Figure 1: Prototype load cell for the measurement of loads on an aerofoil section. (a) Model mounted to load cell in wind tunnel test section. (b) Schematic of photoelastic sensing element. (c) Image of sensor element, showing response to loading.

Shadowgraph particle tracking of vortex rings with low cost hardware (IP, 2021-2022)

Particle tracking velocimetry is becoming an increasingly common tool for a wide variety of aerodynamics problems. A limitation of this technique is that high frame rate video cameras are required to track sequential exposures of particles. Recently, a low-cost solution to this problem was proposed by Aguirre-Pablo et al. (2017). Using the colour filter of smartphone cameras, a single frame can be exposed with sequential pulses of red-green-blue light to recover three shadowgraph exposures of a particle track. This allows the investigation of strongly three-dimensional flow phenomena, such as the formation of vortex rings, to be examined in detail. Here, one outstanding question is what causes vortex rings to stop growing. This phenomenon, called pinch-off, is relevant to the optimisation of pulsed propulsion systems. In this project, you will build a shadowgraphic particle tracking system with low-cost hardware to make 3D measurements of a vortex ring flow field during the early stages of vortex formation.

Shadowgraph particle tracking of vortex rings with low cost hardware
(a)
Shadowgraph particle tracking of vortex rings with low cost hardware
(b)

 

 

 

 

 

 

 

Figure 1: Shadowgraphic illumination system of Aguirre-Pablo et al. (a) Arrangement of cameras, pulsed colour illumination system and vortex generator. (b) Example shadowgraph image, showing particle tracks within an emerging vortex ring.

The Design and Development of a Pulsed LED Array for Particle Image Velocimetry (IP, 2018-2019)

This project investigated the possibility of replacing high-cost laser based illumination with cheaper, pulsed light-emitting diodes for the measurement of fluids by particle image velocimetry. This was achieved by designing, building and testing a 5 x 5 pulsed light-emitting diode array. The illumination output was calculated to provide 1mJ per 10 μs pulse at 25 Hz. The modular design of the array can be easily adapted for further development. The combined cost of the components amounts to around £100. The reduced cost of the LED array means that accessibility to PIV can be increased.

Design and Development of a Pulsed LED Array for Particle Image Velocimetry
Dr. John M Lawson
Engineering, University of Southampton, Highfield, Southampton. SO17 1BJ United Kingdom

Room Number NNN: 176/2045/B1

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