A bypass transition model based on the intermittency function

Ge, Xuan

doi:10.31274/etd-180810-4424

Cited by 11 publications

(18 citation statements)

References 31 publications

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“…The T3C2 case has a lower free-stream intensity and lower Reynolds number than T3C1 and the C f prediction in Ref. 24 is fairly accurate; correspondingly, the inferred and modeled fields were confirmed to be fairly close. The cases presented here are representative of the other T3 cases: The inferred intermittency field shows the region of γ < 1 extending higher into the boundary layer near the inlet and the γ = 1 region is achieved farther inside the downstream boundary layer.…”

Section: B Application To a Transition Modeling Problemsupporting

confidence: 56%

“…These features were selected from a set that included the full velocity gradient tensor, the transported scalars k, ω, γ, and three non-dimensional parameters {ν t /ν; d 2 Ω/ν; Ω/ω} that appear in the original Ge et al 24 model. A standard hill-climbing 27 algorithm was used to narrow down the feature set.…”

Section: Results On Transition Modeling Problemmentioning

confidence: 99%

“…The most significant difference in the T3A and T3B cases is that the inferred field extends higher in the boundary layer near the inlet. This difference explains the the over prediction of C f near the inlet in the original Ge et al 24 model and suggests that the sink term in Eq. 8 needs improvement.…”

Section: B Application To a Transition Modeling Problemmentioning

confidence: 87%

“…The left column in Figure 6 shows the inferred intermittency field. The right column shows the intermittency field obtained using the transition model of Ge et al 24 with the mean flow imposed from the inferred solution. The most significant difference in the T3A and T3B cases is that the inferred field extends higher in the boundary layer near the inlet.…”

Section: B Application To a Transition Modeling Problemmentioning

confidence: 99%

“…The model developed by Ge et al 24 is based on the idea that, in bypass transition under free-stream turbulence, non-zero γ diffuses into the boundary layer, allowing k to be produced, thereby creating eddy viscosity and further enhancing the diffusion of γ. In this way, transition occurs by penetration of free-stream turbulence into the boundary layer via molecular and turbulent diffusion.…”

Section: B Application To a Transition Modeling Problemmentioning

confidence: 99%

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New Approaches in Turbulence and Transition Modeling Using Data-driven Techniques

Duraisamy

Zhang

Singh

2015

53rd AIAA Aerospace Sciences Meeting

151

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A data-driven approach to the modeling of turbulent and transitional flows is proposed in this work, with the goal of developing more robust and accurate closure models. The key idea is to (i) infer the functional form of deficiencies in known closure models by applying inverse problems to computational and experimental data, (ii) use machine learning to reconstruct the improved functional forms, and (iii) to inject the improved functional forms in simulations to obtain more accurate predictions. The inverse modeling step, on its own, can yield valuable insight to the modeler, essentially converting data to information. The machine learning step is a tool to convert information into modeling knowledge. Representative examples are used to describe the methodology and to demonstrate its viability. The first example investigates the modeling of a non-equilibrium turbulent boundary layer, and the second involves the modeling of bypass transition to turbulence. Evidence from these problems emphasizes the utility of the proposed approach in offering new routes to closure modeling in general computational physics disciplines.

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Section: B Application To a Transition Modeling Problemsupporting

confidence: 56%

Section: Results On Transition Modeling Problemmentioning

confidence: 99%

Section: B Application To a Transition Modeling Problemmentioning

confidence: 87%

Section: B Application To a Transition Modeling Problemmentioning

confidence: 99%

Section: B Application To a Transition Modeling Problemmentioning

confidence: 99%

See 3 more Smart Citations

New Approaches in Turbulence and Transition Modeling Using Data-driven Techniques

Duraisamy

Zhang

Singh

2015

53rd AIAA Aerospace Sciences Meeting

151

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Perspectives on the Phenomenology and Modeling of Boundary Layer Transition

Durbin

2017

Flow Turbulence Combust

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This article is a perspective review of boundary layer transition. Both orderly and bypass transition are discussed, but with a decided emphasis on bypass routes. The focus is on transition in a natural, perturbed environment. Then orderly transition occurs through Λ vortices, that develop locally on instability waves. The precursors to bypass transition are boundary layer 'streaks'. Transition proceeds through inner and outer mode secondary instability, leading to patches of turbulence: in zero pressure gradient, bypass transition develops through local, undulatory, outer mode breakdown; in sufficiently adverse pressure gradient, bypass transition proceeds through inner mode instability, which may be of varicose or of helical form.Phenomenology of the creation, growth and breakdown of streaks is surveyed. Theories of shear sheltering, transient and optimal growth, and Orr-Sommerfeld continuous mode resonance are summarized.Recent developments in predictive modeling are summarized. These include laminar fluctuation, and intermittency models.Some open questions are discussed, as are needs for further research.

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