Category Archives: Engineering

Aorta: structure to rupture

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Decorative image from a video showing predicted flow through aortic valve and resultant stress in leaflets of valveRegular readers have probably already realised that I have very broad interests in engineering from aircraft and power stations [see ‘Conversations about engineering over dinner and haircut‘ on February 16th, 2022] to nanoparticles interacting with cells [see ‘Fancy a pint of science‘ on April 27th, 2022].  So, it will come as no surprise to hear that I gave a welcome address to a workshop on ‘Aorta: Structure to Rupture‘ last week.  The workshop was organised in Liverpool by one of my colleagues, with sponsorship from the British Heart Foundation, and I was invited to welcome delegates in my capacity as Dean of the School of Engineering.  It was exciting on two levels: speaking, for the first time in more than two years, to an audience who had travelled from around the world to discuss research. And because the topic was closely associated with cardiac dynamics, which is a field that I worked in for nearly twenty years until around 2006.  I was part of an interdisciplinary team modelling the fluid-structure interaction in the aortic valve as it opens when blood is pumped through it by the heart and then closes to prevent back flow into the heart.  The team dispersed after I moved to the USA in 2004.  So speaking to the workshop last week was something of a trip down memory lane for me and led me to look up our last publication in the field.  I was surprised to find it was cited seven times last year.

The image in the thumbnail is a snapshot from a video showing the predicted time-varying distribution of blood flow through the aortic valve and the resultant distribution of stress in the leaflets of the valve during a heart beat.  The simultation is described in our last publication in cardiac dynamics: Carmody, C. J., Burriesci, G., Howard, I. C., & Patterson, E. A.,  An approach to the simulation of fluid–structure interaction in the aortic valve. J. Biomechanics, 39(1), 158-169, 2006.

Exploiting complexity to help society adapt

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photograph of a flower for decorative purposes onlyI am worried that engineering has become a mechanism for financial returns in an economic system that values profit above everything with the result that many engineers are unwittingly, or perhaps in a few cases wittingly, supporting the concentration of wealth into the hands of a few capitalists.  At the start of the industrial revolution, when engineering innovation started to make a difference to the way we live and work, very few engineers foresaw the impact on the planet of the large scale provision to society of products and services.  Nowadays most engineers understand the consequences for the environment of their work; however, many feel powerless to make substantial changes often because they are constrained by the profit-orientated goals of their employer or feel that they play a tiny role in a complex system.  Complex systems are often characterised by self-organisation in which order appears without any centralised control or planning and by adaptation to change and experience.  Such systems are familiar to many engineers and perhaps they do not, but should, think of the engineering profession as complex system capable of adaptation and self-organisation in which the actions and decisions of individual engineers will cause the emergence of a new order. Our individual impact might be tiny but by acting we influence others to act and the cumulative effect will emerge in ways that no one can predict – that’s emergence for you.

A sign of normality returning

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I am in the midst of marking examination scripts.  I have about two weeks to award a maximum of about 26,000 marks which is a huge number of decisions to make in a relatively short time [see ‘Depressed by exams‘ on January 31st 2018].  Although the pile of examination scripts is tall and the task can feel overwhelming, it represents a return to normality following the pandemic when we conducted on-line, open-book examinations [see ‘Limited bandwidth’ on June 2nd, 2021].  We have been teaching 100% on-campus for the whole semester and all of our examinations have returned to their pre-pandemic format, i.e., the majority have been in-person, closed-book and invigilated.  I have enjoyed teaching thermodynamics in a huge lecture-theatre filled with students and it is relief that I do not have to set examination questions whose answers cannot be found using a search engine or solved using a programme.  Anyway I need to pick up my red pen and return to my marking so only a brief post this week.

Diving into three-dimensional fluids

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My research group has been working for some years on methods that allow straightforward comparison of large datasets [see ‘Recognizing strain’ on October 28th 2015].  Our original motivation was to compare maps of predicted strain over the surface of engineering structures with maps of measurements.  We have used these comparison methods to validate predictions produced by computational models [see ‘Million to one’ on November 21st 2018] and to identify and track changes in the condition of engineering structures [see ‘Out of the valley of death into a hype cycle’ on February 24th 2021].  Recently, we have extended this second application to tracking changes in the environment including the occurance of El Niño events [see ‘From strain measurements to assessing El Niño events’ on March 17th, 2021].  Now, we are hoping to extend this research into fluid mechanics by using our techniques to compare flow patterns.  We have had some success in exploring the use of methods to optimise the design of the mesh of elements used in computational fluid dynamics to model some simple flow regimes.  We are looking for a PhD student to work on extending our model validation techniques into fluid mechanics using volumes of data from measurement and predictions rather than fields, i.e., moving from two-dimensional to three-dimensional datasets.  If you are interested or know someone who might be interested then please get in touch.

There is more information on the PhD project here.