59 results found
Bluck MJ, Wolfendale MJ, 2017, An analytical solution to the heat transfer problem in thick-walled hunt flow, INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW, Vol: 64, Pages: 103-111, ISSN: 0142-727X
Palazzi A, Bluck MJ, Lo S, et al., 2016, Coupling RELAP5-3D and STAR-CCM+ for simulations of steady and transient single phase flows, Pages: 2202-2211
A coupling scheme was developed to couple the CFD software STAR-CCM+ v10.04 and the system code RELAP5-3D v4.2.1. In this paper the structure of the scheme is presented, together with validations for single phase flow in smooth pipes in both transient and steady state cases. Attention was also given to the problem of reconstructing the profile at the inlet of the CFD model under the hypothesis of fully developed flow. This problem arises when flow data has to be passed from the one-dimensional system code to the three-dimensional CFD software.
Bluck MJ, Wolfendale MJ, 2015, An analytical solution to electromagnetically coupled duct flow in MHD, Journal of Fluid Mechanics, Vol: 771, Pages: 595-623, ISSN: 0022-1120
The flow of an electrically conducting fluid in an array of square ducts, separated by arbitrary thickness conducting walls, subject to an applied magnetic field is studied. The analytical solution presented here is valid for thick walls and is based on the homogeneous solution obtained by Shercliff (Math. Proc. Camb. Phil. Soc., vol. 49 (01), 1953, pp. 136-144). Arrangements of ducts arise in a number of applications, most notably in fusion blankets, where liquid metal is used both as coolant and for tritium generation purposes. Analytical solutions, such as those presented here, provide insight into the physics and important benchmarking and validation data for computational magnetohydrodynamics (MHD), as well as providing approximate flow parameters for 1D systems codes. It is well known that arrays of such ducts with conducting walls exhibit varying degrees of coupling, significantly affecting the flow. An important practical example is the so-called Madarame problem (Madarame et al., Fusion Technol., vol. 8, 1985, pp. 264-269). In this work analytical results are derived for the relevant hydrodynamic and magnetic parameters for a single duct with thick walls analogous to the Hunt II case. These results are then extended to an array of such ducts stacked in the direction of the applied magnetic field. It is seen that there is a significant coupling affect, resulting in modifications to pressure drop and velocity profile. In certain circumstances, counter-current flow can occur as a result of the MHD effects, even to the point where the mean flow is reversed. Such phenomena are likely to have significant detrimental effects on both heat and mass transfer in fusion applications. The dependence of this coupling on parameters such as conductivities, wall thickness and Hartmann number is studied.
Bluck MJ, Wolfendale MJ, Marquis AJ, 2015, An analytical solution to the heat transfer problem in Shercliff flow, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, Vol: 86, Pages: 542-549, ISSN: 0017-9310
Wolfendale MJ, Bluck MJ, 2015, A coupled systems code-CFD MHD solver for fusion blanket design, FUSION ENGINEERING AND DESIGN, Vol: 98-99, Pages: 1902-1906, ISSN: 0920-3796
Bluck M, Cinosi N, Walker S, 2014, A multilevel hierarchical preconditioning method for multiscale scattering bodies
This paper considers the solution of the electric field integral equation (EFIE). Hierarchical conforming bases are developed which are subsequently used in the construction of a multilevel Schwarz type preconditioner. The effectiveness of this approach is demonstrated by the computation of scattering from sub-wavelength scattering bodies. The resulting schemes are shown to be faster than conventional schemes up to an order of magnitude.
Bluck MJ, Cinosi N, Walker SP, 2014, A multilevel hierarchical preconditioner for multiscale EM scattering
Cinosi N, Walker SP, Bluck M, et al., 2014, CFD ANALYSIS OF THE FLOW IN CRUD-COATED NUCLEAR ROD BUNDLES, 22nd International Conference on Nuclear Engineering (ICONE22), Publisher: AMER SOC MECHANICAL ENGINEERS
Cinosi N, Walker SP, Bluck MJ, et al., 2014, CFD simulation of turbulent flow in a rod bundle with spacer grids (MATIS-H) using STAR-CCM, NUCLEAR ENGINEERING AND DESIGN, Vol: 279, Pages: 37-49, ISSN: 0029-5493
Palazzi A, Bluck MJ, Lo S, 2014, A coupled RELAP5-3D/STAR-CCM+ simulation for the calculation of friction factor in pipes, Pages: 1323-1329
The thermal hydraulic analysis of nuclear reactors is largely performed by what are known as "System Codes". These codes predict the flows in the complex network of pipes, pumps, vessels and heat exchangers that together form the thermal hydraulic systems of a nuclear reactor. These codes have been used for many decades, and are now very well established, and given this long process of refinement, they are able to produce remarkably accurate predictions of plant behaviour under both steady and transient conditions. Modern CFD is able to produce high-quality predictions of flows in complex geometries, but only with the use of large computing resources. It would be impractical to build a CFD model of, for example, the entire primary circuit of a PWR. However, much of the primary circuit may well be able to be modelled with adequate fidelity using a cheaper one-dimensional system code, and it may only be in a limited part of the circuit that full three-dimensional effects are important. In this paper, the coupling tool present in the STAR-CCM+ v8.02 software was used, together with RELAP5-3D v4.0.3, to perform a coupled analysis of single phase flow in a circular pipe in order to evaluate Moody's friction factor. Three different cases were studied, following two different models. The first case consisted in using smooth walls for the pipe, whereas, in the second and the third ones, the roughness of the wall was set to 20 μm and 50 μm respectively. The first model consisted in using RELAP5-3D for the upstream part of the pipe and STAR-CCM+ for the downstream part. In the second model, instead, STAR-CCM+ was used for the upstream part of the pipe and RELAP5-3D for the downstream part. The results obtained with these two models have been compared with each other to check for possible incongruences. Furthermore, all the results have been compared with standalone simulations performed with RELAP5-3D and STAR-CCM+ and with experimental data (Moody's diagram).
Bluck M, Cinosi N, Walker S, 2013, A p-MUS Preconditioner for the EFIE, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, Vol: 61, Pages: 5547-5552, ISSN: 0018-926X
Bluck M, Cinosi N, Walker S, 2013, A multilevel hierarchical preconditioner technique for multiscale and complex em scattering bodies, Pages: 1519-1522
This paper considers the solution of the combined field integral equation (CFIE) for lossy/dielectric problems. Hierarchical conforming bases are developed which are subsequently used in the construction of a multilevel Schwarz type preconditioner. The effectiveness of this approach is demonstrated by the computation of scattering in free space from a range of spheres with different permittivity (non PEC material). The resulting schemes are shown to be faster than conventional schemes. © 2013 IEEE.
Bluck MJ, Cinosi N, Walker SP, 2013, A multilevel hierarchical preconditioner for multiscale EM scattering
Integral equation schemes, both EFIE and MFIE, have become a powerful tool, particularly with the development of accelerated schemes such as the fast multipole method (FMM). Key to most such treatments is the requirement to solve matrix equations iteratively, which at their core involve matrixvector multiplications. Much of the cost of such solutions then depends on the number of iterations and the cost per iteration. The vast majority of integral equations implementations employ the simplest Rao-WiltonGlisson (RWG) basis functions on triangles. High order interpolatory bases have been developed which (in principle) offer improved accuracy for a given cost. Within the current developments, the next natural step beyond high order interpolatory methods is to arrange these bases hierarchically, as already experienced within the finite element community. Of themselves hierarchical bases offer little more than their high order interpolatory counterparts. However, as has been demonstrated in finite elements it is possible to employ this hierarchical structure to great effect in the reduction of the computational cost of the underlying iterative scheme via a multilevel Schwarz type preconditioner. In this paper we attempt to apply such hierarchical bases and their associated acceleration schemes to integral equations. The results suggest that their efficacy depend strongly on the scattering regime. In particular, high frequency problems (those where the wavelength is the principal determinant of mesh size) are shown to benefit little from hierarchical functions. Unlike their finite element counterparts, equivalent p-MUS integral equation schemes appear to offer little gain, if any, over nonhierarchical schemes. On the other hand, for ̀low frequency' problems, such as scattering of objects with sub-wavelength features (where geometry is the main determinant of mesh size), there are significant improvements in performance over corresponding interpolatory schemes. Copyright &
Bluck MJ, 2012, Conforming Hierarchical Basis Functions, COMMUNICATIONS IN COMPUTATIONAL PHYSICS, Vol: 12, Pages: 1215-1256, ISSN: 1815-2406
Cinosi N, Bluck M, Walker S, 2012, Application of Time-Domain BIE to sub-wavelength Scattering Bodies with Finite Conductivity, International Conference on Electromagnetics in Advanced Applications (ICEAA) / IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (IEEE APWC) / URSI Electromagnetic Environment and Interference Symposium (EEIS), Publisher: IEEE, Pages: 1177-1179
Bluck M, Cinosi N, Walker S, 2011, A multilevel hierarchical preconditioner for the electric field integral equation, Pages: 1180-1183
This paper considers the solution of the electric field integral equation (EFIE). Hierarchical conforming bases are developed which are subsequently used in the construction of a multilevel Schwarz type preconditioner. The effectiveness of this approach is demonstrated by the computation of scattering from a range of perfectly conducting objects including spheres, cubes, plates and dihedrals. The resulting schemes are shown to be faster than conventional schemes by approximately an order of magnitude. © 2011 IEEE.
Cinosi N, Haq I, Bluck M, et al., 2011, The effective thermal conductivity of crud and heat transfer from crud-coated PWR fuel, NUCLEAR ENGINEERING AND DESIGN, Vol: 241, Pages: 792-798, ISSN: 0029-5493
Cinosi N, Walker S, Bluck M, 2011, Time-domain bie analysis of large electromagnetic scattering problems with Impedance Boundary Condition, Pages: 1172-1175
Methods for solving the electromagnetic scattering of computationally large problems in a fast and efficient way are well established. However their application is limited to PEC scattering bodies, whilst when applied to lossy or conducting materials they become inefficient and less desirable. In this paper we extend the capabilities of these fast methods to solve for non-dispersive conductors by using the approximation of the Impedance Boundary Condition. © 2011 IEEE.
D'Arcy M, Weiss D, Bluck M, et al., 2011, Adsorption kinetics, capacity and mechanism of arsenate and phosphate on a bifunctional TiO2-Fe2O3 bi-composite, JOURNAL OF COLLOID AND INTERFACE SCIENCE, Vol: 364, Pages: 205-212, ISSN: 0021-9797
ul Hag I, Cinosi N, Bluck M, et al., 2011, Modelling heat transfer and dissolved species concentrations within PWR crud, NUCLEAR ENGINEERING AND DESIGN, Vol: 241, Pages: 155-162, ISSN: 0029-5493
Ahmad M, Alexandrou I, Al-Nuaimy W, et al., 2010, WCE 2010 - World Congress on Engineering 2010: Preface, WCE 2010 - World Congress on Engineering 2010, Vol: 2
Cinosi N, Walker SP, Bluck MJ, 2009, Integral equation transient analysis of experiments on electromagnetic scattering from sub-wavelength apertures, International Conference on Electromagnetics in Advanced Applications (ICEAA 2009), Publisher: IEEE, Pages: 537-540
Bluck MJ, Walker SP, 2008, Polynomial basis functions on pyramidal elements, COMMUNICATIONS IN NUMERICAL METHODS IN ENGINEERING, Vol: 24, Pages: 1827-1837, ISSN: 1069-8299
Bluck M J, Walker S P, 2007, High-Order Discrete Helmholtz Decompositions for the Electric Field Integral Equation, IEEE Transactions on Antennas and Propagation, Vol: 55, Pages: 1338-1347, ISSN: 0018-926X
Cinosi N, Walker SP, Bluck MJ, 2007, Transient near field analysis of optical modes in sub-wavelength arrays, Workshop on Computational Electromagnetics in Time-Domain, Publisher: IEEE, Pages: 104-107
Cinosi N, Walker SP, Refig A, et al., 2007, Integral equation time domain analysis of frequency-dependent transmission through aperture arrays, Pages: 960-963
Whereas a single sub-wavelength aperture transmits little light, much greater transmission is observed through an array of such apertures. Plainly the apertures interact, at a length scale related to their spacing, and encourage the transmission of the light through the small holes. This behaviour is studied via solution of the governing Maxwell equations in the space surrounding the perforated plate, and the field distributions associated with this anomalous transmission are investigated. © 2007 IEEE.
Bluck MJ, Hatzipetros A, Walker SP, 2006, Application's of differential forms to boundary integral equations, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, Vol: 54, Pages: 1781-1796, ISSN: 0018-926X
Bluck MJ, Hatzipetros A, Walker SP, 2006, Applications of differential forms to boundary integral equations, Antennas and Propagation, IEEE Transactions on, Vol: 54, Pages: 1781-1796, ISSN: 0018-926X
Bluck MJ, Walker SP, 2005, Algebraic topology and computational electromagnetics, Pages: 853-856
In this paper we discuss the application of algebraic topology to computational electromagnetics. Basic homology and cohomology theory is explained in the context of numerical schemes. We will show how these concepts influence the choice of discrete spaces for both finite and boundary element methods. Spaces on simplicial manifolds (triangles, tetrahedra), cartesian product manifolds (quadrilaterals, hexahedra) and prismatic manifolds are easily constructed in the light of these topological considerations. In particular, Nedelec, Raviart-Thomas, Whitney and Rao-Wilton-Glisson type function spaces are easily obtained as special cases. This approach is not restricted to affine manifolds with results being equally valid for the general curvilinear case. In general an adjoint form of the commuting de Rham diagram is shown to hold and how this property affect convergence is discussed.
Cinosi N, Walker SP, Bluck MJ, 2004, Modelling of sub-wavelength optical apertures in thin metal sheets via 3D transient Maxwell's equations, New York, 5th international conference on numerical simulation of optoelectronic devices, 19 - 22 September 2005, Berlin, GERMANY, Publisher: Ieee, Pages: 99-100
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