Applied Mathematics Seminars
This is only an overview page. For complete details of the venue, speakers and calendar links, please see HERE
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13th Jan
2014 Anatomically-based models of the placenta and its interactions with the maternal circulation.
Alys Clark (University of Auckland, NZ)
3:00 - Room 1.212 Alan Turing BuildingAbstract (click to view)The placenta provides the developing foetus with the nutrients that it requires through pregnancy. Maternal and placental blood are physically separated, but functionally coupled: blood flow and oxygenation in each circulation can affect the other. Structural abnormalities in both the maternal and placental blood vessels are associated with a host of pregnancy complications, and so understanding how structure relates to function in these blood vessels may be key to understanding why and how pregnancies can go wrong. Furthermore, the outer layer of the placenta sheds a numerous aggregates of nuclei which have been found in large numbers in the maternal lung. These aggregates are shed in higher numbers in complicated pregnancies, and while this is widely thought to be a secondary component of pathology there is evidence that they are potentially dangerous to maternal cells. I will describe how anatomically-based computational models can be used to test some of the hypotheses regarding the relationship between the maternal and placental circulations in pregnancy. I will then discuss how we intend to translate data obtained across multiple spatial scales into new insights regarding normal and abnormal placental development using mathematical models.
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29th Jan
2014 MSc. Project Presentations
2:00 - - Room 1.212 Alan Turing Building -
5th Feb
2014 Some new classes of free-boundary problems.
Yulii Shikhmurzaev (University of Birmingham)
2:00 - Room 1.212 Alan Turing Building -
12th Feb
2014 Colloidal particles confined to fluid interfaces: numerical and mathematical analysis of capillary forces, particle adsorption, and particle transport.
Lorenzo Botto (Queen Mary University of London)
2:00 - - Room 1.212 Alan Turing Building -
5th Mar
2014 On Beach Formation and Dredging in Multi-Phase Hele-Shaw Flows.
Onno Bokhove (University of Leeds)
2:00 - - Room 1.212 Alan Turing BuildingAbstract (click to view)Fluid-particle interactions are investigated using quasi-2D Hele-Shaw cells. Firstly, Hele-Shaw experiments with beach and berm formation under driven and breaking waves will be presented. The mathematical design of this Hele-Shaw beach cell is triggered by analysing width- and depth-averaged hydrodynamic equations, such that the minimal gap width necessary for sustained wave breaking can be determined. The beach profiles found in the Hele-Shaw cell will be compared with gravel beach profiles in much larger wave tanks and numerical results in the literature. Secondly, some new pilot experiments on particle dredging will be shown.
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12th Mar
2014 Mathematical tales of a sperm tail
Hermes Gadêlha (The University of Oxford)
2:00 - - Room 1.212 Alan Turing BuildingAbstract (click to view)Active cell motility via the controlled movement of a flagellum beating is among the phylogentically oldest forms of motility; and has been retained in higher level organisms for spermatozoa transport. Despite this ubiquity and importance, the details of how the flagellar waveform emerges from the underlying mechanics and how the cell, or the environs, may control the beating pattern by regulating the flexible tail is far from fully understood. We demonstrate in this talk that mechanics and modelling can be utilised to interpret observations of flagellar dynamics, swimming trajectories, beating patterns, as well as unexpected phenomena associated with their complex material response. It also highlights that this is a fertile and challenging area of inter-disciplinary research for applied mathematicians and demonstrates the importance of future observational and theoretical studies in understanding the underlying mechanics of these motile cell appendages.
- 19th Mar
2014 Energy spectra of finite temperature superfluid turbulence
Demos Kivotides (Imperial College, London)
2:00 - - Room G.207 Alan Turing BuildingAbstract (click to view)In the hydrodynamic regime of Bose-Einstein condensed quantum fluids, a superfluid mean field interacts via mutual friction forces with the quantum fluctuations comprising the normal fluid. In this talk, we indicate first the connections between microscopic physics and hydrodynamic modeling before moving on to the problem of fully developed turbulence at hydrodynamic scales and finite temperatures. We analyse energy spectra scalings of fully developed turbulence in terms of interactions between quantized superfluid vortices and coherent normal fluid vortical structures. We present results from numerical computations indicating that mutual friction acts as an effective classical viscous stress removing kinetic energy from the normal fluid; the latter preserves its inertial regime Kolmogorov scaling, while a new scaling regime appears at its diffusive high wavenumber scales; in this low Reynolds number flow regime, it is superfluid vortex reconnections and their associated Kelvin waves that induce fluctuations in the normal fluid. On the superfluid side, there is a low wavenumber Kolmogorov like scaling (associated with superfluid vortex polarization by the large normal fluid eddies) and a steeper high wavenumber scaling regime associated with normal fluid induced vortical patterns in the superfluid. We comment on current efforts to understand this phenomenology via statistical field theoretical modeling of turbulence fluctuations in the two fluids.
- 26th Mar
2014 Synthetic Micro-Swimming
Eric Lauga (University of Cambridge)
2:00 - - Room G.108 Alan Turing BuildingAbstract (click to view)A number of microorganisms are able to self-propel in a fluid, including many bacteria, spermatozoa, ciliates, and plankton. Inspired by the biological world, the engineering community been very active in designing and implementing synthetic swimming strategies. In this talk we will start by an introduction to the micro-fluid mechanics of such small-scale swimming. We will then introduce three specific propulsion methods (magnetic, chemical and acoustic) and outline some of the mathematical and physical questions they generate.
- 2nd Apr
2014 Tractable Choice-Based Network Revenue Management.
Arne Strauss (Warwick Business School)
2:00 - - Room 1.212 Alan Turing BuildingAbstract (click to view)Models incorporating customer behaviour, as customers choosing from an offer set of products made available by the firm, have recently become popular in assortment optimization and revenue management. The dynamic program for deciding the best offer set is intractable. A popular approximation to the dynamic program is a deterministic linear program called the CDLP which has an exponential number of columns. When there are products considered for purchase by more than one customer segment, CDLP is difficult to solve in general as the column generation subproblem is known to be NP-hard, even a 2-segment multinomial-logit mixture model of choice. However, recent research indicates that a formulation based on segments with additional constraints (SDCP+) is tractable and approximates the CDLP value very closely. We investigate the structure of the consideration sets that makes the SDCP+ formulation exactly equal to CDLP. We show that if the segment consideration sets follow a tree structure, CDLP has the same objective value as SDCP+, giving insight into the structure of the CDLP formulation as well as identifying a tractable modeling construct. We give a counterexample to show that cycles can induce a gap between the CDLP and the SDCP+ relaxation. When the consideration set structure contains cycles, we give two new classes of cycle-based constraints called flow and synchronization constraints, that tighten the upper bound on the dynamic program. We develop a new primal-based policy based on these new formulations and show numerically the performance of these cycle-based cuts.
- 23rd April
2014 Skipping, Sloshing and Washboarding
Neil Balmforth (The University of British Columbia)
2:00 - - Room G.108 Alan Turing Building- 7th May
2014 Extensional instabilities in complex fluids.
Suzanne Fielding (Durham University)
2:00 - - Room 1.212 Alan Turing Building- 14th May
2014 The influence of surfactant on the stability of a liquid bilayer coating a compliant tube.
David Halpern (University of Alabama)
2:00 - - Room 1.212 Alan Turing BuildingPrevious Seminars
- 19th Mar