Application of LES-quality criteria to internal combustion engine flows

Mare, Francesca di; Knappstein, Robert; Baumann, Michael A.

doi:10.1016/j.compfluid.2013.11.003

Cited by 44 publications

(23 citation statements)

References 22 publications

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“…It is important to note that several other LES-quality indicators have been proposed; 9,10 however, as mentioned by Baumann et al, 11 the application to engine flows is not straightforward. A systematic investigation of various quality indicators in engine LES was performed by Di Mare et al; 12 this concluded that despite several shortcomings (mainly due to the complexity of the flow), most of them can be used to assess the local resolution quality, and they provide guidance especially where underresolution might occur.…”

Section: Introductionmentioning

confidence: 99%

Scale-resolving simulations in engine combustion process design based on a systematic approach for model development

Hasse

2015

International Journal of Engine Research

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The increasing availability of high-performance computing resources will allow scale-resolving simulations such as large eddy simulations to be used instead of unsteady Reynolds-averaged Navier-Stokes approaches, not only in academic research but also for engine combustion process development. The scope of this work is to highlight and discuss this transition to scale-resolving simulations and to propose a systematic approach for model development and application. The current and future scope of industrial and academic research is discussed especially with respect to cycle-to-cycle variations, which cannot be identified with unsteady Reynolds-averaged Navier-Stokes models. The individual processes along the cause-and-effect chain leading to cyclic variations of the combustion process are identified, and the current state of scale-resolving simulations and the required models with respect to these processes are discussed.

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Section: Introductionmentioning

confidence: 99%

Scale-resolving simulations in engine combustion process design based on a systematic approach for model development

Hasse

2015

International Journal of Engine Research

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“…The idea is simple, a change in sign of the correlation R yy along the horizontal sampling line or R xx along the vertical sampling line can be considered as a very coarse estimation of the radius of the vortex [37]. More detailed explanation and discussion of the method can be found in the papers [12,38]. Figure 10 shows the calculated two-point correlation function R(r) along two chosen sampling lines.…”

Section: Dissipation Ratementioning

confidence: 99%

“…The sub-grid kinetic energy k sgs (x, t) can be modeled from the phase averaged strain rate tensor hS ij i 2 according to Equation (12) [12,44] with the constant C i set to 0.202: Figure 14 shows the distributed value of M (x, t) as computed from the in-cylinder flow at À270, À180, À90 CAD. As discussed, six investigated schemes lead to results that satisfy the "good LES criterion" related to resolved kinetic energy.…”

Section: Les Quality Criteriamentioning

confidence: 99%

“…Focusing on engine simulations, some authors [12,37] have applied several LES quality indices [11,13]. These LES indices are used to estimate, whether a given resolution is sufficient for a "good LES".…”

Section: Les Quality Criteriamentioning

confidence: 99%

“…This leads to a misleading situation where many commonly used LES quality criteria must fail. Criteria based on the amount of modeled turbulent kinetic energy [11,12], as well as the criteria based on the ratio between the turbulent and the laminar viscosity (as proposed by Celik et al [13]), will no longer be adequate.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of Numerical Effects on the Flow and Combustion in LES of ICE

Nguyen

Kempf

2017

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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-This work investigates the influence of numerical dissipation on the modeled combustion in Large Eddy Simulations (LES). It is well known that capturing the dynamics of the in-cylinder flow is crucial for engine simulations, as it strongly affects flame propagation. The flame propagation during the power-stroke highly depends on the turbulence level that is developed throughout compression. This turbulence level will be strongly influenced by the accuracy of the numerical schemes employed. Even a small extent of upwinding, filtering, low-order implicit time-stepping, cell-stretching or mapping between grids may affect the flow field, the turbulence level, and hence the turbulent flame speed and the pressure curve. To provide a reference, the LES in-house code PsiPhi is used, which ensures a minimum of dissipation due to high order explicit time-stepping, homogeneous and isotropic filters and cells. Good stability of the code permits the use of a second-order Central Differencing Scheme (CDS) for the transport of momentum, avoiding numerical dissipation. To analyse the effect of numerical dissipation, simulations of a fired engine are performed using different numerical schemes for the convection of momentum. Physical quantities including the total kinetic energy, the velocity gradient, the turbulent viscosity, the in-cylinder pressure, the flame propagation or the burning rate of different test cases are evaluated and compared to each other to show the numerical effects on combustion. Furthermore, the suitability of common LES quality criteria including an energy criterion and viscosity ratio is discussed based on the comparison of simulations with less and more accurate numerics. It is shown that these LES quality indicators can be highly misleading.

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On the Evolution of the Flow Field in a Spark Ignition Engine

Janas

Wlokas

Böhm

et al. 2016

Flow Turbulence Combust

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The development of the turbulent flow field inside a spark ignition engine is examined by large-eddy simulation (LES), from the intake flow to the tumble break-down. Ten consecutive cold flow engine cycles on a coarse and twenty cycles on a fine grid are simulated and compared to experiments of the same engine. The turbulent subgrid scales are modeled by the standard Smagorinsky and by the recently developed Sigma model. A comparison of the intake flow is made against Particle Image Velocimetry (PIV) measurements along horizontal and vertical lines and to an LES simulation performed by the Darmstadt group. Furthermore, we show the first LES comparison to Magnetic Resonance Velocimetry (MRV conducted by Freudenhammer et al.) measurements, which provided the 3D flow field inside a full scale dummy of the entire upper cylinder head including the valve seat region, at a time which mimics inflow conditions of the corresponding engine. Our LES is in good qualitative and quantitative agreement with the simulation and the experiments, with the notable exception of the measured in-cylinder pressure,

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Application of LES-quality criteria to internal combustion engine flows

Cited by 44 publications

References 22 publications

Scale-resolving simulations in engine combustion process design based on a systematic approach for model development

Scale-resolving simulations in engine combustion process design based on a systematic approach for model development

Investigation of Numerical Effects on the Flow and Combustion in LES of ICE

On the Evolution of the Flow Field in a Spark Ignition Engine

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