Intermittency based RANS bypass transition modelling

Lodefier, Koen; Merci, Bart; Langhe, Chris De; Dick, Erik

doi:10.1504/pcfd.2006.009484

Cited by 10 publications

(15 citation statements)

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“…However, adaptations for globally averaged Navier-Stokes equations are made as well. Our work has some similarity with the work of Suzen et al and Pecnik et al The approach adopted in this paper is an unsteady extension of the steady model developed by the present authors [20,21]. A preliminary version of the model was presented in [19].…”

Section: Introductionsupporting

confidence: 65%

“…Apparently, the build-up of turbulence by the turbulence model is too strong. This observation is not really surprising, as it is known from steady flow simulations [20,21] that the SST model has a very large production of turbulence when applied to a laminar-like velocity profile. A similar phenomenon was observed by Lardeau and Leschziner [15] via simulation with a non-linear eddy viscosity model without intermittency modelling.…”

Section: T106a ( Re 2c =160000)mentioning

confidence: 63%

“…This is obtained with diffusion set to zero, which is correct in the near-wall zone. With the local velocity scale (F s = 1), steady bypass transition in attached decelerated flow is adequately described [20,21]. This is also the case for wake turbulence induced bypass transition in attached decelerating flows.…”

Section: Equation For Near-wall Intermittency Factor γmentioning

confidence: 93%

“…The k − ω model, in high-Reynolds form, typically produces a very early and very rapid transition, being completely unphysical [20,21]. The objective of an intermittency based technique is to modify the transitional behaviour of a turbulence model and to control it by using the description of the intermittency.…”

Section: Modifications Of the Turbulence Modelmentioning

confidence: 99%

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Modelling of Unsteady Transition in Low-Pressure Turbine Blade Flows with Two Dynamic Intermittency Equations

Lodefier

Dick

2006

Flow Turbulence Combust

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A transition model for describing wake-induced transition is presented based on the SST turbulence model by Menter and two dynamic equations for intermittency: one for near-wall intermittency and one for free-stream intermittency. In the Navier-Stokes equations, the total intermittency factor, which is the sum of the two, multiplies the turbulent viscosity computed by the turbulence model. The quality of the transition model is illustrated on the T106A test cascade for two Reynolds numbers, using experimental results by Stieger and Hodson for transition mainly due to kinematic wake impact on a separation bubble. The quality of the model is also revealed on the T106D test cascade using experimental results from Hilgenfeld, Stadtmuller and Fottner for wake turbulence induced transition. The test cases differ in pitch to chord ratio, Reynolds number and inlet free-stream turbulence intensity, causing different transition mechanisms. The unsteady results are presented in space-time diagrams of shape factor and wall shear stress on the suction side. The results show the capability of the model to capture the physics of unsteady transition in separated state. Inevitable shortcomings are revealed as well.Nomenclature F s = starting function for intermittency U = local velocity (m/s) U ∞ = free-stream velocity (m/s) γ = near-wall intermittency factor ζ = free-stream intermittency factor τ = turbulence weighting factor μ = molecular viscosity (Pa s) μ t = turbulent viscosity (Pa s) θ = momentum thickness Re θ = momentum thickness Reynolds number ρ ∞ U ∞ θ/μ

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Section: Introductionsupporting

confidence: 65%

Section: T106a ( Re 2c =160000)mentioning

confidence: 63%

Section: Equation For Near-wall Intermittency Factor γmentioning

confidence: 93%

Section: Modifications Of the Turbulence Modelmentioning

confidence: 99%

See 2 more Smart Citations

Modelling of Unsteady Transition in Low-Pressure Turbine Blade Flows with Two Dynamic Intermittency Equations

Lodefier

Dick

2006

Flow Turbulence Combust

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show abstract

“…Most of bypass transition models are mostly based on the concept of the intermittency coefficient according to Narasimha [3] and/or of the laminar kinetic energy (see Walters, Leylek [4]). Besides transition models with a transport equation for the intermittency coefficient, as Suzen, Huang [5], Langtry [6] or Langtry, Menter [7], Lodefier et al [8], there are models with the algebraic relation for the intermittency coefficient, e.g. Thermann, Niehuis [9] and/or Straka, PĜíhoda [10].…”

Section: Introductionmentioning

confidence: 99%