Short Research Visits
UKFN is pleased to invite proposals for SRVs. The call is open to anyone working in fluid mechanics in the UK. The following pdf gives the context of the call and sets out the information you need to provide in your proposal:
Proposals will be assessed in batches every 4 months. The next deadline is 30 September 2017.
Advancing Atmospheric Models: Aspects of Spatial DiscretisationDr Joanna Szmelter Wolfson School of Mechanical, Electrical and Manufacturing Engineering Loughborough University Visiting: Dr Nils Wedi, Dr Christan Kühnlein & Prof Piotr Smolarkiewicz, ECMWF (European Centre for Medium-Range Weather Forecasts)
ECMWF is currently developing a ground breaking non-hydrostatic atmospheric dynamics Finite Volume Module (FVM) which will be implemented in the ECMWF’s Integrated Forecasting System (IFS). The IFS is the operational tool used to provide medium range weather prediction services for the UK and most EU countries.
Many aspects of the spatial discretisation employed in the FVM originated from Dr Szmelter’s earlier work on unstructured mesh models for fluid flows. In recent years, these have been substantially advanced by ECMWF to take advantage of the IFS environment and High Performance Computing.
The main goal of the SRV is to discuss and initiate the implementation of an alternative discretisation of selected operators, which could potentially offer further improvements to the module in terms of accuracy and speed. Suitable numerical tests will be defined and set up. Dr Szmelter will also explore whether some of the advancements achieved for atmospheric flows in the FVM could be applied to other engineering and environmental flows.
Controlling nematic microfluidics: a merger of modelling, simulation and experimentsDr Apala Majumdar Department of Mathematical Sciences University of Bath Visiting: Dr Ian Griffiths (Mathematical Institute, University of Oxford)
Nematic liquid crystals (NLCs) are complex non-Newtonian fluids – anisotropic fluids with a degree of long-range orientational ordering. A rapidly growing research theme concerns “nematic microfluidics” or the flow of NLCs confined to thin channels. Experimentalists are keen to exploit nematic microfluidics for new applications in hydrodynamics, transport phenomena and next-generation pharmaceutical applications such as drug delivery.
The introduction of nanoparticles into NLCs modifies the fluid properties, and understanding this effect may lead to new applications. Some earlier collaborative work between Drs Majumdar and Griffiths on the flow of nanoparticles in nematic microfluidics showed interesting effects, especially in cases with multiple nanoparticles.
The SRV will therefore focus primarily on the flow of nanoparticles in nematic microfluidics, and through a combination of modelling, simulation and experiments, will address issues such as:
- how the nanoparticles interact with the fluid flow and the nematic orientation, and vice-versa;
- how this interaction can be manipulated to produce desired agglomerates with desired properties;
- how the shape and size of nanoparticles can be varied to manipulate the rheology;
- assessing the predictions of different mathematical theories for nematodynamics and how they compare to experiments.
Exploration of integrated microfluidics with phononics and acoustofluidics based on thin-film platformDr Richard Fu Department of Maths, Physics and Electrical Engineering Northumbria University Visiting: Dr Julien Reboud & Dr Rab Wilson (University of Glasgow)
The SRV will initiate proof-of-concept collaborative work to develop phononic structures (Glasgow) on thin-film ZnO surface acoustic wave devices (Northumbria). This has the potential of creating ultra-low-cost acoustofluidics devices, capable of carrying out complex microfluidic processing of samples for applications in flexible and wearable healthcare monitoring. Dr Fu will fabricate and test different designs of acoustofluidic device.
Prior to the SRV, suitable ZnO-coated substrate samples will be prepared at Northumbria, while Glasgow will carry out calculations to confirm the microstructure geometry to be used. Then:
- In the James Watt Nanofabrication Centre at Glasgow, different phononic structures (pillars or holes) will be patterned and fabricated on the ZnO-film-coated substrates
- The ultrasonic surface vibration patterns will be validated using a high-frequency laser Doppler vibrometer (frequency range in the 10’s of MHz)
- The microfluidic performance of fabricated devices will be tested using (i) conventional microfluidic test beds to look at streaming, flowing, jetting and nebulisation; and (ii) a high-frame-rate camera (up to 1MHz)
Following the SRV, the data will be used in support of new collaborative research bids, and in discussions with interested industrial partners who could develop microfluidics products for healthcare applications.
Interrogating local shear effects on coherent structure identification in turbulent flowsDr Chris Keylock University of Sheffield Visiting: Dr Oliver Buxton (Department of Aeronautics, Imperial College, London)
Dr Buxton has obtained three-dimensional experimental data on the behaviour of various turbulent flows (boundary layers, wakes, shear layers). With 3D data, the full velocity gradient tensor is available for analysis, and we will apply various vortex identification schemes to extract flow structure information. However, most of these methods are eigenvalue-based, so we will also derive complementary methods that incorporate effects excluded from consideration in an eigenvalue-based approach. Hence, we will be able to identify structures that are clear in both types of approach, as well as those that are better represented in one than the other. We will then seek to explain these differences in terms of local energy production and dissipation. Such analyses will inform the physical basis for future turbulence closures.
Towards a mechanistic understanding of haematocrit changes in tumour vasculatureDr Miguel O. Bernabeu Centre for Medical Informatics The University of Edinburgh Visiting: Prof Helen Byrne (Mathematical Institute, University of Oxford)
Several authors have reported anomalous blood flow patterns in tumour vasculature, including deviations from the typical haematocrit (red blood cell count) distributions observed in healthy tissue. Such abnormalities present a challenge for drug delivery and have been linked to tumour hypoxia and angiogenesis.
To date, most computational models of tumour blood flow view the blood as a homogeneous fluid and employ phenomenological rules to determine haematocrit changes at vessel bifurcations. Such models fail to capture the dynamics encountered in tumours. This is, in part, due to the computational challenges associated with simulating haematocrit changes in a mechanistic way, i.e. using a model of interacting deformable particles to describe the transport of red blood cells (RBCs) in the plasma.
The SRV will initiate a collaboration between the groups of Prof Byrne and Dr Bernabeu to exploit their complementary expertise:
- Prof Byrne and colleagues have considerable experience of simulating blood flow and oxygen distribution in tumours and have recently developed a microfluidics assay that recapitulates RBC dynamics in tumour vascular networks.
- Dr Bernabeu and colleagues have recently extended HemeLB, their blood flow simulation platform that treats blood as a suspension of red blood cells (http://www.archer.ac.uk/community/eCSE/eCSE01-010/eCSE01-010.php).
The SRV will focus on constructing and validating computational models of blood flow in realistic tumour microvasculature, based on experimental data recently obtained by Prof Byrne and colleagues. These models will be used to develop a mechanistic model of haematocrit changes.