Imperial College London

ProfessorSpencerSherwin

Faculty of EngineeringDepartment of Aeronautics

Professor of Computational Fluid Mechanics
 
 
 
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Contact

 

+44 (0)20 7594 5052s.sherwin Website

 
 
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Location

 

313BCity and Guilds BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

348 results found

Kazakidi A, Sherwin SJ, Weinberg PD, 2007, Reverse flow in arterial branches influences wall shear stress patterns around branch ostia, Joint Autumn Meeting of the British-Society-for-Cardiovascular-Research/British-Atherosclerosis-Society, Publisher: B M J PUBLISHING GROUP, ISSN: 1355-6037

Conference paper

Vincent PE, Sherwin SJ, Weinberg PD, 2007, Computational investigation of a mechanism by which blood flow could control lipoprotein uptake by the arterial, Joint Autumn Meeting of the British-Society-for-Cardiovascular-Research/British-Atherosclerosis-Society, Publisher: B M J PUBLISHING GROUP, ISSN: 1355-6037

Conference paper

Lee KE, Parker KH, Sherwin SJ, Car CGet al., 2007, The effects of geometrical configurations on steady flow in non-planar double bends, World Congress on Medical Physics and Biomedical Engineering, Publisher: SPRINGER-VERLAG BERLIN, Pages: 3461-+, ISSN: 1680-0737

Conference paper

Alastruey J, Parker KH, Peiro J, Byrd SM, Sherwin SJet al., 2007, Modelling the circle of Willis to assess the effects of anatomical variations and occlusions on cerebral flows, JOURNAL OF BIOMECHANICS, Vol: 40, Pages: 1794-1805, ISSN: 0021-9290

Journal article

van Loon R, Anderson PD, van de Vosse FN, Sherwin SJet al., 2007, Comparison of various fluid–structure interaction methods for deformable bodies, Computers and Structures, Vol: 85, Pages: 833-843, ISSN: 0045-7949

Journal article

Dongbin Xiu, Spencer Sherwin, 2007, Parametric uncertainty analysis of pulse wave propagation in a model of a human arterial network, J. Computational Physics, Vol: 226, Pages: 1385-1407

Journal article

Matthys KS, Alastruey J, Peiro J, Khir AW, Segers P, Verdonck PR, Parker KH, Sherwin SJet al., 2007, Pulse wave propagation in a model human arterial network: Assessment of 1-D numerical simulations against in vitro measurements, J. Biomech., Vol: 40, Pages: 3476-3486

A numerical model based on the nonlinear, one-dimensional (1-D) equations of pressure and flow wave propagation in conduit arteries is tested against a well-defined experimental 1:1 replica of the human arterial tree. The tree consists of 37 silicone branches representing the largest central systemic arteries in the human, including the aorta, carotid arteries and arteries that perfuse the upper and lower limbs and the main abdominal organs. The set-up is mounted horizontally and connected to a pulsatile pump delivering a periodic output similar to the aortic flow. Terminal branches end in simple resistance models, consisting of stiff capillary tubes leading to an overflow reservoir that reflects a constant venous pressure. The parameters required by the numerical algorithm are directly measured in the \emph{in-vitro} set-up and no data fitting is involved. Comparison of experimental and numerical pressure and flow waveforms shows the ability of the 1-D time-domain formulation to capture the main features of pulse wave propagation measured throughout the system test. As a consequence of the simple resistive boundary conditions used to reduce the uncertainty of the parameters involved in the simulation, the experimental set-up generates waveforms at terminal branches with additional non-physiological oscillations. The frequencies of these oscillations are well captured by the 1-D model, even though amplitudes are overestimated. Adding energy losses in bifurcations and including fluid inertia and compliance to the purely resistive terminal models does not reduce the underdamped effect, suggesting that wall visco-elasticity might play an important role in the experimental results. Nevertheless, average relative root-mean-square errors between simulations and experimental waveforms are smaller than 4% for pressure and 19% for the flow at all 70 locations studied.

Journal article

KELee, KH Parker, CG Caro, SJ Sherwinet al., 2007, The spectral/hp element modelling of steady flow in non-planar double bends, Int. J. Num. Meth. Fluids, Vol: in press

Journal article

Alastruey J, Parker KH, Peiró J, Sherwin SJet al., 2006, Can the modified Allen's test always detect sufficient collateral flow in the hand? A computational study., Comput Methods Biomech Biomed Engin, Vol: 9, Pages: 353-361, ISSN: 1025-5842

Blood flow in the largest arteries of the arm up to the digital arteries is numerically modelled using the one-dimensional equations of pressure and flow wave propagation in compliant vessels. The model can be applied to different anatomies of arterial networks and can simulate compression of arteries, these allowing us to simulate the modified Allen's test (MAT) and to assess its suitability for the detection of sufficient collateral flow in the hand if radial blood supply is interrupted. The test measures blood flow in the superficial palmar arch before and during compression of the radial artery. The absence of reversal flow in the palmar arch with the compression indicates insufficient collateral flow and is referred to as a positive MAT. This study shows that small calibres of the superficial palmar arch and insufficient compression of the radial artery can lead to false-positive results. Measurement of the drop in digital systolic pressures with compression of the radial artery has proved to be a more sensitive test to predict the presence of sufficient ulnar collateral flow in networks with small calibres of the superficial palmar arch. However, this study also shows that digital pressure measurements can fail in detecting enough collateral flow if the radial artery is insufficiently compressed.

Journal article

Kirby RM, Sherwin SJ, 2006, Aliasing errors due to quadratic nonlinearities on triangular spectral /hp element discretisations, JOURNAL OF ENGINEERING MATHEMATICS, Vol: 56, Pages: 273-288, ISSN: 0022-0833

Journal article

Eskilsson C, Sherwin SJ, Bergdahl L, 2006, An unstructured spectral/hp element model for enhanced Boussinesq-type equations, COASTAL ENGINEERING, Vol: 53, Pages: 947-963, ISSN: 0378-3839

Journal article

Sherwin SJ, Kirby RM, Peiro J, Taylor RL, Zienkiewicz OCet al., 2006, On 2D elliptic discontinuous Galerkin methods, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Vol: 65, Pages: 752-784, ISSN: 0029-5981

Journal article

Kirby RM, Sherwin SJ, 2006, Stabilisation of spectral/hp element methods through spectral vanishing viscosity: Application to fluid mechanics modelling, COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING, Vol: 195, Pages: 3128-3144, ISSN: 0045-7825

Journal article

Abdessemed N, Sherwin SJ, Theofilis V, 2006, Linear stability of the flow past a low pressure turbine blade, Pages: 1496-1510

The present work is concerned with linear BiGlobal instabilities of flow in a cascade of Low-pressure turbine (LPT) blades. In particular the three-dimensional instability of two-dimensional time-periodic basic states past a T106/3 blade is investigated using Floquet theory and a high-order spectral/hp-element scheme, used for both the basic flow and the instability calculations. The two-dimensional bifurcation of steady to time-periodic flow has been identified in the framework of earlier work on the present project.1 The present Floquet analysis shows that the time-periodic flow becomes three-dlmensionally unstable soon after the two dimensional transition. Two modes of significance have been identified, associated to the separation bubble and the wake of the basic state. Three-dimensional DNS initialized on the identified Floquet eigenmodes at low amplitudes confirms the results of linear stability analysis. Besides the completion of the eigenvalue-based analyses, first-ever transient-growth results of an essentially nonparallel flow have been obtained. In particular, the pseudospectrum of the flow under consideration has been identified and new mechanisms have been revealed, demonstrating the potential for three-dimensional transition as consequence of transient growth.

Conference paper

Broadhurst M, 2006, Vortex Stability and Breakdown: Direct Numerical Simulation and Stability Analysis using BiGlobal and Parabolised Formulations

This thesis concerns the application and implementation of recently developed stability techniques to the understanding of vortex stability and breakdown. The instability anal- ysis of vortical flows was originally motivated by a need to understand the breakdown of aircraft wake vortices and the physics of the vortex breakdown phenomenon. A more recent application is the stability analysis of the vortex wake developed from a Formula 1 front wing. Typically, the model problem when considering vortex dominated flows is the Batch- elor trailing vortex. The results of a BiGlobal linear stability analysis of a Batchelor vortex show that there are many unstable helical perturbation modes covering a wide range of axial wavenumbers. Direct numerical simulation of a corresponding unstable helical distur- bance developing on an axially periodic vortex demonstrates a non-linear energy transfer mechanism responsible for a loss of energy in the mean flow. Relaxing the assumption of periodicity allows axial gradients to develop, and leads to an abrupt drop in axial velocity indicative of vortex breakdown. Direct numerical simulations of a vortex in external pres- sure gradients also suggests that axial pressure gradients significantly influence the onset of vortex breakdown. With a BiGlobal stability analysis assuming axial homogeneity and neglecting streamwise gradients, this motivates the need for an analysis technique that can account for both velocity and pressure gradients. One such technique is the parabolised stability equations, and the current research has successfully implemented this technique and demonstrated its validity by comparing the results with direct numerical simulation.

Thesis dissertation

Sherwin SJ, Eskilsson C, 2006, Spectral/hp discontinuous Galerkin methods for modelling 2D Boussinesq equations, Journal of Computational Physics, Vol: 212, Pages: 566-589, ISSN: 0021-9991

Journal article

Broadhurst MS, Theofilis V, Sherwin SJ, 2006, Spectral element stability analysis of vortical flows, 6th IUTAM Symposium on Laminar-Turbulent Transition, 13 - 17 December 2004, Bangalore, INDIA, Publisher: Springer, Pages: 153-158

Conference paper

Giordana S, Sherwin SJ, Peiro J, Doorly DJ, Crane JS, Lee KE, Cheshire NJW, Carco CGet al., 2005, Local and global geometric influence on steady flow in distal anastomoses of peripheral bypass grafts, JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME, Vol: 127, Pages: 1087-1098, ISSN: 0148-0731

Journal article

Gambaruto AM, Radaelli A, Doorly DJ, Sherwin SJ, Peiro Jet al., 2005, Sensitivity study on by-pass graft reconstruction with emphasis on flow solutions, Pages: 832-833

Conference paper

Xiu D, Sherwin SJ, Dong S, Karniadakis GEet al., 2005, Strong and auxiliary forms of the semi-Lagrangian method for incompressible flows, Journal of Scientific Computing, Vol: 25, Pages: 323-346, ISSN: 0885-7474

Journal article

Sherwin SJ, Blackburn HM, 2005, Three-dimensional instabilities and transition of steady and pulsatile axisymmetric stenotic flows, JOURNAL OF FLUID MECHANICS, Vol: 533, Pages: 297-327, ISSN: 0022-1120

Journal article

Pitt RE, Sherwin SJ, Theofilis V, 2005, BiGlobal stability analysis of steady flow in constricted channel geometries, 8th ICFD Conference on Numerical Methods for Fluid Dynamics, Publisher: WILEY, Pages: 1229-1235, ISSN: 0271-2091

Conference paper

Miliou A, Mortazavi I, Sherwin S, 2005, Cut-off analysis of coherent vortical structure identification in a three-dimensional external flow, COMPTES RENDUS MECANIQUE, Vol: 333, Pages: 211-217, ISSN: 1631-0721

Journal article

Eskilsson C, Sherwin SJ, 2005, Discontinuous galerkin spectral/hp element modelling of dispersive shallow water systems, JOURNAL OF SCIENTIFIC COMPUTING, Vol: 22-3, Pages: 269-288, ISSN: 0885-7474

Journal article

Giordana S, Sherwin SJ, Peiro J, Doorly DJ, Papaharilaou Y, Caro CG, Watkins N, Cheshire N, Jackson M, Bicknall C, Zervas Vet al., 2005, Automated classification of peripheral distal by-pass geometries reconstructed from medical data, JOURNAL OF BIOMECHANICS, Vol: 38, Pages: 47-62, ISSN: 0021-9290

Journal article

Sherwin SJ, Peiro J, 2005, Finite difference, finite element and finite volume methods for partial differential equations, Handbook of materials modeling, Editors: Yip, Yip, Berlin, Publisher: Springer, Pages: 1-30, ISBN: 9781402032875

Book chapter

Alastruey J, Parker KH, Peiro J, Sherwin SJet al., 2005, A one-dimensional simulation of the human conduit arteries compared to experimental data, ASME Summer Biongineering Conference, abstract 0328683, Vail, CO, USA

Conference paper

Karniadakis G, Sherwin S, 2005, Spectral/hp element methods for computational fluid dynamics, Oxford, Publisher: Oxford University Press, ISBN: 9780198528692

Book

Abdessemed N, Sherwin SJ, Theofilis V, 2004, On unstable 2d basic states in low pressure turbine flows at moderate reynolds numbers

Results are presented of BiGlobal stability analysis of incompressible flow over a row of T-106/300 Low Pressure Turbine blades. In particular the two- and three-dimensional stability of a two-dimensional steady state is investigated for Reynolds numbers below 915. Both structured and unstructured meshes have been used at different degrees of refinement, while variations of the polynomial order of the numerical methods in either approach have ensured numerical convergence. The analysis shows that the transition from steady to periodic flow takes place at a Reynolds number of Rec = 905 ± 10. The flow remains linearly stable to three-dimensional disturbances below Rec. The leading eigenvalues of three-dimensional BiGlobal eigenmodes of the LPT flow have been obtained in a range of Reynolds and spanwise wavenumber parameters. The two most interesting eigenmodes have been found to be related with the wake of the blade and the separated flow in the trailing-edge region on the suction side of the blade. © 2004 by the American Institute of Aeronautics and Astronautics, Inc.

Conference paper

Blackburn HM, Sherwin SJ, 2004, Formulation of a Galerkin spectral element-Fourier method for three-dimensional incompressible flows in cylindrical geometries, JOURNAL OF COMPUTATIONAL PHYSICS, Vol: 197, Pages: 759-778, ISSN: 0021-9991

Journal article

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