Numerical assessment of wall modelling approaches in scale-resolving in-cylinder simulations
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2018-12-01
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en
Pages
19
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International Journal of Heat and Fluid Flow, Volume 74, pp. 154-172
Abstract
Wall modelling in internal combustion engines (ICEs) is a challenging task due to highly specific boundary layers and a dynamically changing flow environment. Recent experimental (Jainski et al., 2013, Renaud et al., 2018) and direct numerical simulation (DNS, Schmitt et al., 2015a) studies demonstrate that scaled near-wall velocity and temperature profiles in ICEs deviate considerably from the law of the wall. Utilising the DNS data, the present paper focusses on benchmarking a scale-resolving approach with a 1-D non-equilibrium wall model (HLR-WT, Keskinen et al., 2017) in ICE-like flows. Specific emphasis is put on the compression stroke using different grids and two additional wall-modelled large eddy simulation (WMLES) reference approaches. The standard wall law based WMLES-1 produces highly grid-dependent underprediction of wall fluxes, to which WMLES-2 (Plensgaard and Rutland, 2013) and HLR-WT, employing engine-targeted wall treatments, yield considerable improvement. Differences between the improved methods are noted in detailed metrics. Throughout the compression stroke, HLR-WT provides a good match to the DNS in scaled mean boundary layer profiles for both velocity and temperature. With relevance to local heat flux distribution, the characteristic impingement-ejection process observed in the DNS is qualitatively replicated with WMLES-2 and HLR-WT. The non-equilibrium formulation of the latter allows for slight improvements in terms of local heat transfer fluctuation predictions. In contrast, coarse near-wall grids appear to be detrimental for such predictions with all approaches. The study provides evidence on the potential of the HLR-WT and WMLES-2 approaches in ICE near-wall flow prediction, advocating further investigations in more realistic engine configurations.Description
Keywords
Compression stroke, Engine flows, Wall heat transfer, Wall modelling, Wall-modelled large eddy simulation
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Citation
Keskinen, K, Koch, J, Wright, Y M, Schmitt, M, Nuutinen, M, Kaario, O, Vuorinen, V, Larmi, M & Boulouchos, K 2018, ' Numerical assessment of wall modelling approaches in scale-resolving in-cylinder simulations ', International Journal of Heat and Fluid Flow, vol. 74, pp. 154-172 . https://doi.org/10.1016/j.ijheatfluidflow.2018.09.016