Wavy surfaces

Numerical simulations by Hooke and Venner et al. [57,58] for small amplitude wavy surfaces show that the amplitude attenuation of waviness in an EHL contact depends on the operating conditions and the orientation of the roughness pattern. They found that the attenuation appeared to be governed by a single nondimensional parameter the ratio of the wavelength to the length of the inlet pressure sweep at the entrance to the conjunction, it can be evaluated by... 

Annular flow, wavy interface (Henry, 1971) Under this condition the virtual mass of gas flowing over a wavy surface can be approximated by flow over a surface made of continuous rows of half-cylinders ... 

Common defects that are observed in this coating technique are voids, pin holes, thickness variations, and wavy surfaces. Voids and pinholes are caused by air entrapment in the film, surface contamination, or dust particles. 

Crystal faces with curved or wavy surfaces, not exhibiting either striations or step patterns, are rarely encountered. In most cases, these faces appear by dissolution. Rough interfaces grow by the adhesive-type growth mechanism, their normal... 

Although there are numerous published investigations in which records of the wavy surface profile have been obtained, e.g. (H9, D16, Sll), not many of these have been analyzed for information on wavelengths, most being concerned with wave-size (height) distributions. However, it may be noted that the experimental wavelengths of Kapitsa and Kapitsa (K10) show a trend in the direction of the data reported above, even at very small Reynolds numbers (lVa < 25). It seems, therefore, that the Kapitsa theory is applicable only at very small flow rates, as far as wave characteristics are concerned, in the case of the free flow of wavy films. Allen (A3) has reported a similar conclusion. 

Fig. 5. Types of two-phase How in a horizontal pipeline (a) Stratified smooth flow where gas velocity is low. Liquid flows along bottom portion of pipelines with essentially a smooth surface, (b) Stratified flow with a wavy. surface, the waviness caused by increased gas flow velocity, (c) Liquid bridges the pipeline cross section, thus causing slugs or plugs of liquid, which move at a velocity approximately that of ihe flowing gas, (d) Annular flow, in which the liquid essentially flows as an annular film on the pipe wall while gas flows as in a centra) core of the pipe, (e) Dispersed bubble flow usually results when liquid flow rates are high and gas rates are low. Because of comparative density differences, most bubbles are found above the pipe center line. Conditions vary somewhat when the pipeline is in a vertical orientation. After Cindric, Gandhi, and Williams)...

Pockrand I, Raether H (1976) Surface plasma oscillations in silver films with wavy surface profiles a quantitative experimental study. Opt Commun 18 395-399... 

Suppose we imagine cleavage along the (100) face of a-CraOs. We can obtain a wavy surface which contains O - and Cr3+ ions in the same surface and which is electrically neutral. A strip of this surface is shown... 

II Strong slicken side lineations Slightly wavy surfaces Shear (11)... 

Smith, J. D., McLean, S. R., 1977. Spatially averaged flow over a wavy surface. Journal of Geophysical Research 82 (12), 1735-1746. 

Wootz steel later became known as Damascus steel because sword blades made from it had wavy surface patterns like Damask fabric. Damascus steel became famous because these swords kept their sharpness and strength after many battles. The knowledge of how to make Damascus steel was lost in the 1800s, but recently the process was redeveloped under the name superplastic steel. Collector hunting knives worth thou sands of dollars are being made from superplastic steel. 

In Figure 8 (right) the transfer coefficients are plotted as a function of the waterside friction velocity. The theoretical curves for a smooth surface based on a diffusion model (Deacon 1977) and for a rough surface based on a surface renewal model (Danckwerts 1970) are also included. The theoretical curve for a smooth surface (no waves were visually observed) is in good agreement with the measurements when a surfactant was present. For a clean interface, the transfer coefficient follows the theoretical curve for a surface renewal model with a wavy surface. 

Damascus Steel. This was a very high quaiity ancient steei with a beautifui wavy surface pattern used in making sword biades. it seems to have come mainiy from india. 

In this example, is the intended chip thickness, which is defined by the machine s feed rate. Due to resonant vibrations, the process leaves a wavy surface on the workpiece. The resulting chip thickness h i) is now calculated from the difference between the present and the previous tooth period (Eq. 4) ... 

Rough wavy surface (applesauce) wrong resin/temperature too low or high. 

Wavy surface Screw clearance set improperly Puller drive slipping Adjust clearance Adjust or replace puller drive... 

Keywords Roughness waviness surface finishing 3D measurement. 

It is obvious that a particle sitting on a surface will adhere diffeently when there is roughness. This is clear from Fig. 9.11 which shows three situations smooth surfaces, wavy surfaces with large diameter roughness, and rough surfaces with small diameter asperities. 

Figure 9.11. (a) Smooth particle on smooth surface (h) particle adhering better to a wavy surface (c) (ess adhesion on surface with sharp asperities. 

We now proceed as in the stabihty analyses of Chapter 5 and suppose that perturbation shifts the interface from the plane z = 0 in the moving coordinate system to the wavy surface z givrai by We further suppose that the... 

Rough, wavy surfaces resulting in a poor surface appearance of the part. 

Wavy surface appearance of an object molded from thermoplastic resins, caused by improper flow of the resin into the mold. Also see Splay marks. ... 

Geometric aspects can also be important, as illustrated by control of the spreading of mammalian cells on wavy PDMS surfaces. Wavy surfaces were generated by stretching a sheet of the elastomer, exposing it to a oxygen plasma, and the allowing it to relax. 

Attempts to explore this complicated interaction and to model the response of the eddy viscosity and turbulent shear stresses to the time variation of pressure gradients in turbulent air flow over a solid wavy surface have been made by Thorsness et al. [85] and Abrams and Hanratty [89]. Large variations of the amplitude and phase angle of the surface shear stress with the dimensionless wave number were predicted (Figure 3). The analysis shows that the surface shear stress fluctuation is shifted upstream with respect to the wave elevation and the phase shift varies in the range of 0-80° in comparison to the constant phase shift predicted by Benjamin [84],... 

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