Boundary layer parameters

FIG. 6-49 Boundary layer parameters for continuous cylindrical surfaces. (From Sakiadis, Am. Inst. Chem. J., 7, 467 [1.961].)... 

The meteorological input required in the Unified EMEP model are the 3D horizontal and vertical wind fields, specific humidity, potential temperature cloud cover, and precipitation. The transferred surface 2D fields for use in the chemical transport model are surface pressure, 2 m temperature, surface flux of momentum, sensible and latent heat, and surface stress. All variables are given in 3-h interval. Table 13.1 lists the variables and their main purposes in the EMEP model. Inside the model different boundary layer parameters like the stability, eddy diffusion, and mixing height are calculated based on MOST. 

For consistent calculation of boundary layer parameters in off-line coupling the land-use classes in the meteorological model should ideally match the land-use classes presented in EMEP (Table 13.2). In the coupling with HIRLAM, where only... 

ACTM models can make use of atmospheric parameters that are output from some parametrization schemes. Boundary layer parameters have to be calculated inside ACTM models or in pre-processing if they are not available from the meteorological model. Entrainment and detrainment rates in cumulus clouds could be provided if sufficiently sophisticated cumulus parametrization is used in the meteorological model. 

This relation along with (3.132) and with the relation Ux = Uh + ln + l) constitute the algebraic system sufficient for the determination of all three integral boundary layer parameters Uh, U , and zh. The latter equation set reduces to one transcendental equation for the mixing length parameter Zh = zh/h... 

From the foregoing local results, the average boundary-layer parameters may be determined. If the flow is laminar over the entire boundary layer length, L, the average mass-transfer coefficient is given by... 

Where k = 0.4, A = 5.5 are the usual Newtonian boundary layer parameters. This expression is plotted in Fig. 5, which... 

In the region behind the DMR structure (Fig. 8), one can similarly define local boundary layer parameters ... 

It should be noted that for polymerization-modified perlite the strength parameters of the composition algo go up with the increasing initial particle size. [164]. In some studies it has been shown that the filler modification effect on the mechanical properties of composites is maximum when only a portion of the filler surface is given the polymerophilic properties (cf., e.g. [166-168]). The reason lies in the specifics of the boundary layer formation in the polymer-filler systems and formation of a secondary filler network . In principle, the patchy polymerophilic behavior of the filler in relation to the matrix should also have place in the failing polymerization-modified perlite. 

GP 11] [R 5] A judgement on mass-transfer limitations on the reaction rate according to the Mears criterion was made [121], This inequality predicts no such limitations in the boundary layer when the Mears criterion is smaller than 0.15. Using process parameter data applied in a number of experiments, the highest... 

For a very thin liquid film, the value of 3 cannot be evaluated, and it should be replaced by a new parameter 3, using the generalized turbulent boundary-layer profile in an adiabatic flow as in Reference (Levy and Healzer, 1980). GF can be solved stepwise along the pipe until the G value goes to zero, where dryout occurs. This analysis was performed to compare the calculated g"rit with Wurtz data (Wurtz, 1978) and also to compare with the predictions by the well-known Biasi et al. correlation (1968), as shown in Figure 5.90. For the limited data points compared, the agreement was good. 

The next parameter varied was the location of the susceptor within the deposition zone. Variations of the susceptor location did not affect film stoichiometry, but they did influence the morphologies of the films. When the susceptor was moved toward the evaporation zone, denser, smoother, and shinier looking films were obtained from a reduced concentration boundary layer (less diffusion-limited) toward the evaporation zone. 

The concentration of the substrate S is also uniform throughout the boundary layer. This case is often called chemical regime , because the limiting phenomenon is the chemical reaction and not the physical process of mass transfer. In that case, the gas-liquid contact area (A, o, oL...) is not a crucial parameter conversely, the liquid retention (eL) must be high to promote the reaction. 

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