Comparison of structured- and unstructured-grid, compressible and incompressible methods using the vortex pairing problem

Tsoutsanis, Panagiotis; Kokkinakis, Ioannis; Könözsy, László; Drikakis, Dimitris; Williams, R. J. R.; Youngs, D. L.

doi:10.1016/j.cma.2015.04.010

Cited by 83 publications

(57 citation statements)

References 43 publications

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“…The Mach number for the left and right states are calculated based on the velocity magnitude of all the velocity components independent of the normal direction in which the flux is computed. This modification is different in nature from a preconditioning step used for changing the flow variables, since our main motivation is not to relax the restriction in terms of the time-step size, but rather to increase the resolution at low speed regions, where this modification has demonstrated increased resolution and accuracy for a wide-range of flow problems [1,2,32,33,54], can be utilised with any Riemann solver and without computational overheads.…”

Section: Low-mach Number Treatment Modificationmentioning

confidence: 99%

“…The diagonal elements of the matrix must be stored and inverted directly and the off-diagonal ones are computed at every stage. Hence, the diagonal elements used in the present study are scalars multiplied by the identity matrix and the off-diagonals are computed according to equation (33). The number of sweeps per Newton iteration is set to 5 in the present study, based on the findings of various approaches using the LU-SGS schemes for similar flow problems [56][57][58][59][60][61].…”

Section: Time Discretisationmentioning

confidence: 99%

“…Furthermore, low Mach number effects can become important in near wall regions as well as in flow regions where vortical structures are 2 dominant [32,33]. Numerical methods designed for compressible flows should be assessed for their accuracy in these flow regions.…”

Section: Introductionmentioning

confidence: 99%

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Assessment of high-order finite volume methods on unstructured meshes for RANS solutions of aeronautical configurations

2017

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This version is available at https://strathprints.strath.ac.uk/59947/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. Assessment of High-Order Finite Volume Methods on Unstructured Meshes for RANS Solutions of Aeronautical Configurations.Antonis F. Antoniadis a, * ,P a n a g i o t i sT s o u t s a n i s referenced data and discussed in terms of accuracy, grid dependence and computational budget.

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Section: Low-mach Number Treatment Modificationmentioning

confidence: 99%

Section: Time Discretisationmentioning

confidence: 99%

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Assessment of high-order finite volume methods on unstructured meshes for RANS solutions of aeronautical configurations

2017

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“…The aforementioned contributions made attempts to obtain very accurate results within the framework of LES and ILES methods to gain a deeper insight into the behaviour of the physics of turbulence. The reader can refer to the application of the ILES method in different contexts [14][15][16][17][18], where the quantification of numerical dissipation and dispersion could also be employed to improve the accuracy of the numerical solution.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Numerical Dissipation in Classical and Implicit Large Eddy Simulations

2017

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Abstract:The quantitative measure of dissipative properties of different numerical schemes is crucial to computational methods in the field of aerospace applications. Therefore, the objective of the present study is to examine the resolving power of Monotonic Upwind Scheme for Conservation Laws (MUSCL) scheme with three different slope limiters: one second-order and two third-order used within the framework of Implicit Large Eddy Simulations (ILES). The performance of the dynamic Smagorinsky subgrid-scale model used in the classical Large Eddy Simulation (LES) approach is examined. The assessment of these schemes is of significant importance to understand the numerical dissipation that could affect the accuracy of the numerical solution. A modified equation analysis has been employed to the convective term of the fully-compressible Navier-Stokes equations to formulate an analytical expression of truncation error for the second-order upwind scheme. The contribution of second-order partial derivatives in the expression of truncation error showed that the effect of this numerical error could not be neglected compared to the total kinetic energy dissipation rate. Transitions from laminar to turbulent flow are visualized considering the inviscid Taylor-Green Vortex (TGV) test-case. The evolution in time of volumetrically-averaged kinetic energy and kinetic energy dissipation rate have been monitored for all numerical schemes and all grid levels. The dissipation mechanism has been compared to Direct Numerical Simulation (DNS) data found in the literature at different Reynolds numbers. We found that the resolving power and the symmetry breaking property are enhanced with finer grid resolutions. The production of vorticity has been observed in terms of enstrophy and effective viscosity. The instantaneous kinetic energy spectrum has been computed using a three-dimensional Fast Fourier Transform (FFT). All combinations of numerical methods produce a k −4 spectrum at t * = 4, and near the dissipation peak, all methods were capable of predicting the k −5/3 slope accurately when refining the mesh.

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“…It modifies and replaces the previously used lower-order scheme of piecewise parabolic method (PPM). Similar to the PPM scheme, this WENO reconstruction is performed in a dimension-bydimension fashion (as also done in [210,211]), working along one-index direction at a time. Therefore, thef (u − , u + ) is extended for expressing the 2-D fluxes:…”

Section: Truncatedmentioning

confidence: 99%

Micro/mesoscale combustion based portable power generating system

Kang¹

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Micro/mesoscale combustion-driven power generation is a promising alternative to replace traditional batteries for powering small scale electronics owing to its much higher energy densities. However, the considerable heat losses from the combustor walls due to the dramatically increased surface-tovolume ratio, as well as the short flow residence time at small scales pose a technical challenge in stabilising the flame inside the micro/mesoscale combustor. On the other hand, the significantly enhanced flame-wall thermal coupling at small scales can also lead to some unique flame characteristics.Recently, solid state power conversion of the heat released in the micro/mesoscale combustor such as thermoelectric (TE) and thermophotovoltaic (TPV) has been favoured over traditional power conversion methods such as micro-turbines. This is due to the excessive mechanical and viscous losses that rotating machinery suffers from upon miniaturisation.One of the main aims of this thesis is to perform numerical simulations to investigate the fundamental aspects of micro/mesoscale combustion, such as micro-flame behaviours of propagation and stabilisation, the conditions under which flame dynamics occur and the choices that suppress them. A set of modelling techniques that gives guidelines and practices for performing the time-accurate micro/mesoscale combustion simulations has been developed through investigation. Knowledge on standard and well-accepted numerical methods in literature are collected in a cohesive document. The less well-established modelling choices have been thoroughly evaluated and discussed.Using the developed numerical models, the effects of hydrogen and carbon monoxide addition on premixed methane/air flame dynamics is investigated. Results show that the flame instabilities which exist in pure methane/air flames could be effectively suppressed via a small amount of additives. Deep understanding of the underlying physics and chemistry has been gained. The effects of wall temperature profiles on the simulated micro-flame behaviours are also studied. The role of the combustion heat release and the gas-solid heat transfer in determining the micro-flame propagation speed is identified.Experimental works are also carried out, towards a full system demonstration for micro-power generation. The focus is placed on the "wall thermal engineering" on the improvement of the combustor performance and power output. The thermally-orthotropic pyrolytic graphite for the combustor wall material is explored. Compared to an isotropic material of stainless steel, a widened flame stability limit with pyrolytic graphite is demonstrated. Moreover, a uniform and moderate temperature distribution over the combustor surface is achieved, which is favourable for thermoelectric power conversion applications. Meanwhile, a novel, compact mesoscale thermophotovoltaic power generating system using a combination of porous media combustion and a simple band-pass filtering method is developed. The use of the porous media effectively enh...

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Comparison of structured- and unstructured-grid, compressible and incompressible methods using the vortex pairing problem

Cited by 83 publications

References 43 publications

Assessment of high-order finite volume methods on unstructured meshes for RANS solutions of aeronautical configurations

Assessment of high-order finite volume methods on unstructured meshes for RANS solutions of aeronautical configurations

Investigation of Numerical Dissipation in Classical and Implicit Large Eddy Simulations

Micro/mesoscale combustion based portable power generating system

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