Unsteady vortex structures in the wake of nonaxisymmetric bumps using spiral MRV

Ching, David S.; Elkins, Christopher J.; Alley, Marcus T.; Eaton, John K.

doi:10.1007/s00348-018-2599-8

Cited by 6 publications

(5 citation statements)

References 29 publications

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“…The 50 • bump has a single dominant longitudinal vortex existing through the entire wake. Temporal features of the flow, most notably a quasi-periodic wake shedding cycle, agree closely with experimental results presented by Ching et al (2018b). The LES results allow a more detailed look at the temporal features than was possible using the experiments.…”

Section: Discussionsupporting

confidence: 82%

“…Figure 17 is a schematic of the wake vortex dynamics, showing alternating vortices moving across the centreline as they are advected downstream. The reconstructed shedding cycle here is consistent with the experimental results from Ching et al (2018b).…”

Section: Reconstructed Cycle Analysissupporting

confidence: 88%

“…Figure 14 shows the first SPOD mode at the shedding frequency for the plane located at X/H = 4 in the wake of the 10 • bump. Because SPOD modes have arbitrary phase, the phase of the modes in figure 14 appear different from the SPOD modes in Ching et al (2018b). SPOD modes operate at fixed frequency, so the modes show correlated fluctuations at the shedding frequency.…”

Section: Quasi-periodic Cycle Reconstruction 421 Spectral Proper Omentioning

confidence: 99%

“…Uncertainties fromChing et al (2018a) are plotted every fourth point on the experimental data. number computed from LES and experiments ofChing et al (2018b).…”

mentioning

confidence: 99%

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Large-eddy simulation study of unsteady wake dynamics and geometric sensitivity on a skewed bump

Ching

Eaton

2019

J. Fluid Mech.

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Section: Discussionsupporting

confidence: 82%

Section: Reconstructed Cycle Analysissupporting

confidence: 88%

Section: Quasi-periodic Cycle Reconstruction 421 Spectral Proper Omentioning

confidence: 99%

“…Uncertainties fromChing et al (2018a) are plotted every fourth point on the experimental data. number computed from LES and experiments ofChing et al (2018b).…”

mentioning

confidence: 99%

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Large-eddy simulation study of unsteady wake dynamics and geometric sensitivity on a skewed bump

Ching

Eaton

2019

J. Fluid Mech.

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“…The case features an upstream concave surface flow and a downstream complicated three-dimensional separation. The flow dynamics of this case was first studied using experiment by [37,38] and LES by [39], primarily focusing on the dynamics of three-dimensional separation bubble and unsteady vortex structures. In the present work, we selected the bump case with the skew angle of 10 • in [39], introduced two independent passive scalars to the flow field, and implemented a new LES for turbulent transport of the two scalars.…”

Section: Scalar Dispersion Around a Skewed Bump 421 Flow Configuratio...mentioning

confidence: 99%

On correcting the eddy-viscosity models in RANS simulations for turbulent flows and scalar transport around obstacles

Hao¹,

Gorlé²,

Ching³

et al. 2022

Preprint

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In Reynolds-averaged-Navier-Stokes (RANS) simulations for turbulent scalar transport, it is common that using an eddy-viscosity (EV) model to close the Reynolds stress yields reasonable mean flow predictions but large errors in scalar transfer results regardless of scalar flux model inadequacies. This failure mode of EV models is generally related to the fact that the transport of momentum and scalar depends on different Reynolds stress components. The present work addresses two common issues relevant to such failures in the scenarios of turbulent scalar transport around obstacles. The first issue is the general overprediction of scalar transfer near the upwind surfaces, which is primarily attributed to the absence of wall-blocking mechanism in conventional EV models. We accordingly propose a Shear-Preserving-Wall-Blocking (SPWB) method to analytically correct the overpredicted wall-normal stress under the realizability constraint. The second issue is the general underprediction of scalar transfer in the downstream large separation regions, which is essentially attributed to the presence of vortex shedding invalidating the scaling ground in conventional EV models' dissipation closures. We accordingly generalize the recently proposed Double-Scale Double-Linear-EV (DSDL) model to scalar transport predictions. Consequently, a combined model, SPWB-DSDL, is developed. The model is then applied to two test cases, of which the first features a bluff obstacle with an upstream impingement flow and a downstream two-dimensional separation and the second features a streamlined obstacle with an upstream concave surface flow and a downstream three-dimensional separation. In the two cases, the SPWB-DSDL model is capable of simultaneously yielding reasonable results of mean flow field, turbulence energy and stress, and scalar transfer in both upstream

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Investigation of geometric sensitivity of a non-axisymmetric bump: 3D mean velocity measurements

2018

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Unsteady vortex structures in the wake of nonaxisymmetric bumps using spiral MRV

Cited by 6 publications

References 29 publications

Large-eddy simulation study of unsteady wake dynamics and geometric sensitivity on a skewed bump

Large-eddy simulation study of unsteady wake dynamics and geometric sensitivity on a skewed bump

On correcting the eddy-viscosity models in RANS simulations for turbulent flows and scalar transport around obstacles

Investigation of geometric sensitivity of a non-axisymmetric bump: 3D mean velocity measurements

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