Effects of Adverse Pressure Gradients on Mean Flows and Turbulence Statistics in a Boundary Layer

Nagano, Yasutaka; Tagawa, Masatoshi; Tsuji, Tomohiro

doi:10.1007/978-3-642-77674-8_2

Cited by 90 publications

(86 citation statements)

References 25 publications

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“…Pressure-gradient correction to the law of the wall The downward shift of the APG profile in figure 2(b) evokes earlier results, both experimental and from DNS (Nagano, Tagawa & Tsuji 1992;Spalart & Watmuff 1993). Seeing such results and having now noted that the velocity law of the wall is favoured over the other two scaling laws, it is tempting to conjecture the existence a 'pressure-gradient law of the wall' in which U + is a function of y + and p + , say, instead of only y + .…”

Section: Test Of the Scaling Lawssupporting

confidence: 85%

The resilience of the logarithmic law to pressure gradients: evidence from direct numerical simulation

2009

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Wall-bounded turbulence in pressure gradients is studied using direct numerical simulation (DNS) of a Couette–Poiseuille flow. The motivation is to include adverse pressure gradients, to complement the favourable ones present in the well-studied Poiseuille flow, and the central question is how the scaling laws react to a gradient in the total shear stress or equivalently to a pressure gradient. In the case considered here, the ratio of local stress to wall stress, namely τ+, ranges from roughly 2/3 to 3/2 in the ‘wall region’. By this we mean the layer believed not to be influenced by the opposite wall and therefore open to simple, universal behaviour. The normalized pressure gradients p+ ≡ dτ+/dy+ at the two walls are −0.00057 and +0.0037. The outcome is in broad agreement with the findings of Galbraith, Sjolander & Head (Aeronaut. Quart. vol. 27, 1977, pp. 229–242) relating to boundary layers (based on measured profiles): the logarithmic velocity profile is much more resilient than two other, equally plausible assumptions, namely universality of the mixing length ℓ = κy and that of the eddy viscosity νt = uτκy. In pressure gradients, with τ+ ≠ 1, these three come into conflict, and our primary purpose is to compare them. We consider that the Kármán constant κ is unique but allow a range from 0.38 to 0.41, consistent with the current debates. It makes a minor difference in the interpretation. This finding of resilience appears new as a DNS result and is free of the experimental uncertainty over skin friction. It is not as distinct in the (rather strong) adverse gradient as it is in the favourable one; for instance the velocity U+ at y+ = 50 is lower by 3% on the adverse gradient side. A plausible cause is that the wall shear stress is small and somewhat overwhelmed by the stress and kinetic energy in the bulk of the flow. The potential of a correction to the ‘law of the wall’ based purely on p+ is examined, with mixed results. We view the preference for the log law as somewhat counter-intuitive in that the scaling law is non-local but also as becoming established and as highly relevant to turbulence modelling.

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Section: Test Of the Scaling Lawssupporting

confidence: 85%

The resilience of the logarithmic law to pressure gradients: evidence from direct numerical simulation

2009

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“…The increase in the wake component is due to the significant decrease in the skin friction along the diffuser. This feature of adverse pressure gradient on the fluid velocity development has been also reported in the literature (see for example Nagano et al, 1993).…”

Section: Resultssupporting

confidence: 79%

“…Both studies measured characteristics of equilibrium turbulent boundary layers where the pressure gradient parameter is kept constant. Nagano et al (1993) experimentally studied the behavior of turbulent boundary layer under moderate and strong adverse pressure gradients. They showed that with increase in adverse pressure gradients, the near wall velocity profile shifts below the standard log-law, indicating a reduction in the viscous sub-layer thickness.…”

Section: Introductionmentioning

confidence: 99%

Computation of Developing Turbulent Flow through a Straight Asymmetric Diffuser with Moderate Adverse Pressure Gradient

Salehi

Raisee

Cervantes

2017

JAFM

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In this paper, numerical investigation of three-dimensional, developing turbulent flow, subjected to a moderate adverse pressure gradient, has been investigated using various turbulence models, namely: the low-v f  and a variant of Reynolds stress model. The results are compared with the detailed velocity and pressure measurements. Since the inlet condition is uncertain, a study was first performed to investigate the sensitivity of the results to the inlet boundary condition. The results showed the importance of including the contraction effects. It is seen that the developing flow inside the straight duct, is highly sensitive to the inlet boundary condition. The comparisons indicate that all turbulence models are able to predict a correct trend for the centerline velocity and pressure recovery inside the straight duct and diffuser but the low-Re k   and RSM turbulence models yield more realistic results. The SST k   model largely overpredicts the centerline velocity and boundary layer thickness in the straight duct. The comparisons of the numerical results also revealed that the RSM model, due to its anisotropic formulation, is able to reproduce the secondary flows. As expected, the RSM model demonstrates the best performance in prediction of the flow field and pressure recovery in the asymmetric diffuser.

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“…This value is far from the standard value of 26, but does not agree with the best fitted value of 11 for APG1. In the experimental work of Nagano et al (1992) however, the formula (23) gave good predictions. Cebeci (1970) proposed the relation,…”

Section: Apg1mentioning

confidence: 96%

Near-wall damping in model predictions of separated flows

Skote

Wallin

2016

International Journal of Computational Fluid Dynamics

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Data from the near-wall region of an attached and a separated turbulent boundary layer are used for the development of near-wall damping functions utilized in turbulence modelling. The model considered is an explicit algebraic Reynolds stress model. The data are taken from two direct numerical simulations. The turbulent boundary layer equation is analyzed in order to extend the validity of existing wall damping functions to turbulent boundary layers under severe adverse pressure gradients.

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Effects of Adverse Pressure Gradients on Mean Flows and Turbulence Statistics in a Boundary Layer

Cited by 90 publications

References 25 publications

The resilience of the logarithmic law to pressure gradients: evidence from direct numerical simulation

The resilience of the logarithmic law to pressure gradients: evidence from direct numerical simulation

Computation of Developing Turbulent Flow through a Straight Asymmetric Diffuser with Moderate Adverse Pressure Gradient

Near-wall damping in model predictions of separated flows

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