Boundary layer turbulence

As the fluid s velocity must be zero at the solid surface, the velocity fluctuations must be zero there. In the region very close to the solid boundary, ie the viscous sublayer, the velocity fluctuations are very small and the shear stress is almost entirely the viscous stress. Similarly, transport of heat and mass is due to molecular processes, the turbulent contribution being negligible. In contrast, in the outer part of the turbulent boundary layer turbulent fluctuations are dominant, as they are in the free stream outside the boundary layer. In the buffer or generation zone, turbulent and molecular processes are of comparable importance. [Pg.66]

Johnson B, Barchi RH (1968) Effect of drag reducing additives on boundary-layer turbulence J Hydronautics 2 108... [Pg.161]

Fig. 6. Boundary layer turbulence reduces width of low-pressure wake...

Greenhut, G.K., and Bean, B.R., Aircraft measurements of boundary-layer turbulance over the central equatorial pacific ocean, Boundary Layer Meteorology, 20, 221-41, 1981. [Pg.243]

Among experimental studies of chemical reactions in turbulent media, fast reactions in tubular reactors with multijet injection of reactants are very popular, since the first experiments of Mao and Toor (34) and Vassiliatos and Toor (35). Their data have been (and are still) extensively exploited for testing theoretical models, although one may ask if homogeneous isotropic turbulence was perfectly controlled in these experiments. In order to rule out this objection, a new series of experiments was recently performed by Bennani et al. (28, 29, 30, 36) in a 0.29 m i.d. tube eliminating the influence of boundary layers. Turbulence was created by a grid and carefully controlled by velocity fluctuation measurements. Previous studies (2) had confirmed that the decrease of Ig with a non-reacting species (passive scalar) obeys Corrsin s equation ... [Pg.148]

Moeng, C.H. (1984) A large-eddy simulation model for the study of planetary boundary-layer turbulence, J. Atmos. Sci. 41, 2052-2062. [Pg.394]

Moeng CH (1984) A Large-Eddy-Simulation Model for the Study of Planetary Boundary-Layer Turbulence. J Atm Sci 41(13) 2052-2062 Moin P, Kim J (1982) Numerical investigation of turbulent channel flow. J Fluid Mech 118 341-377... [Pg.183]

Jackson JL, Webster DR, Rahman S, Weissburg MJ (2007) Bed roughness effects on boundary-layer turbulence and consequences for odor tracking behavior of blue crabs (Callinectes sapidus). Limnol Oceangr 52 1883-1897... [Pg.82]

Kolev, N., and Nakov, S. (1994), Performance characteristics of a packing with boundary layer turbulizers. m. Liquid film controlled mass transfer, Chemical Engineering and Processing, 33(6) 437-442. [Pg.290]

Landahl, M. T. Bark, F. Application of a two-scale boundary layer turbulence model to drag reduction. In C. N. R. S. Colloque Int. Polymferes et Lubrification, Brest. [Pg.26]

BERTSCHLER M., DRACOS T. GYR A. (1979) On the flow structures giving rise to high Reynolds stresses in a turbulent boundary layer. Turbulence in liquids. Dept. Chem. Eng. Univ. of Missouri-Rolla (Proc. 6th Symp. on tub. in liquids Oct. 1979)... [Pg.246]

Quantity Laminar boundary layer Turbulent boundary layer Percolation+ viscous BL loss Coulomb friction loss Viscoelastic (KV) Viscous mud Viscoelastic (Jeffreys)... [Pg.799]

While the viscous drag is greater with a turbulent boundary layer, the pressure drag will be less. At certain values of Reynolds Number, the decrease in pressure drag due to boundary layer turbulence far exceeds the increase in friction drag. In such cases, the total drag decreases with an increase in turbulence in the boundary layer. [Pg.129]

Packings wife vertical walls wife boundary layer turbulizers ... [Pg.252]

Description of the structured packing with boundary layer turbulizers The usage of thermopressed plates for honeycomb packings allows to press on there walls special turtnilizers of the mass transfer boundaiy layer [148-156] for intensification of tibe h and mass transfer processes. A packing block wi such a construction is presented in Fig. 6S. [Pg.294]

To prnlict the pressure drop of dry packings with boundary layer turbulizers, following equation is proposed [153] ... [Pg.296]

Fig. 7S. Comjrarison of the experimental data for fiir pacldnp with boundary layer turbulizers and the pr Bction line computed using Eq. (208) (sc Table 31).

Comparison of the structured packings with boundary layer turbulizers with other highly effective types of packing... [Pg.307]

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