Convection patterns

The hulk solution may become depleted. In free-convection experiments, the cathode and anode compartments are often separated by a diaphragm to prevent interaction of the convection patterns. Under these conditions, replenishment of the catholyte does not take place. Examples of sagging limiting-current plateaus caused by bulk depletion can be found in... 

The most extensive and refined application of microelectrodes, both in the wall of a cell and as a moveable probe, was made by LeLan and Angelino (L2, L3, L4), who charted convection patterns and mass-transfer rate distributions in cylindrical cells with and without baffles. 

Olsen, D. E., M. F. Sudlow, K. Horsf ield and G. F. Filley, Convective Patterns of Flow During Inspiration, Arch. Intern. Med. 131 51-57 (1973). 

A simple example is the rotating disc electrode described in detail in chapter 2. The horizontal spinning disc draws liquid up and then flings it out sideways, creating a continuous but steady-state convection pattern. If the distance down from the disc is denoted by z and the distance across the disc surface by the radial distance, r, then it is not difficult to show that ... 

So we see swirling eddy (or convective ) patterns above a radiator because the density of air is a function of temperature. If all the air had the same temperature, then no such difference in density would exist, and hence we would see no refraction and no eddy currents - which is the case in the summer when the radiator is switched off. Then again, we can sometimes see a heat haze above a hot road, which is caused by exactly the same phenomenon. 

Both diffusion and convection are modes of mass transfer. Typically, large-scale mass transfer is accomplished by convection, and small-scale mass transfer is accomplished by diffusion. Similarly, large-scale heat transfer in the Earth is through convection (mantle convection), and small-scale heat transfer is through heat conduction (e.g., through the lithosphere). To treat the complicated convection pattern and diffusion requires a large computational effort. Some simple problems can be treated analytically. 

In summary, the nonuniformities of the electric field, associated with those of concentration near an inhomogeneous membrane surface, give rise to a volume force that will set in motion the fluid in the diffusion layer. The corresponding convective pattern can be described as follows. 

A pot of water, heated gradually on a stove, is seen to develop highly structured convection patterns ( Benard cells ), resembling a checkerboard of ascending and descending columns. Clearly, such order out of chaos represents a process with A S < 0, proving that the second law is invalid. 

We are interested primarily in the convection pattern close to the electrode surface in order to calculate the flux of electrons. Following Levich [19], we say... 

Because numerical errors due to discretization of a convective term introduce an additional, unphysical diffusion mechanism, termed numerical diffusion (ND), the diffusion coefficient D was set to zero [152], The resulting concentration fields nonetheless are indicative of the distribution of a solute within the micro channel volume. In this way, convective patterns can be derived for the redistribution of the liquid transverse to the flow direction. Accordingly, the stretching, tilting and thinning of liquid lamellae can be followed. 

Physical situations that involve radiation with convection are fairly common. Examples include solar radiation interacting with the earth s environment to produce complex natural convection, water environmental studies for predicting natural convection patterns in lakes, seas and oceans, and heat transfer along copper tubes in the furnace of a boiler. 

Habne, E. W. P. Heat Transfer and Natural Convection Patterns on a Horizontal Circular Plate, Int. J. Heat Mass Transfer, vol. 12, p. 651, 1969. 

V. Croquette, P. Le Gal, A. Pocheau, and R. Guglielmetti, Large-scale characterization in a Rayleigh-Benard convective pattern, Europhys. Lett., 1, 393-399 (1986). 

Systems that exchange entropy with their surroundings may undergo spontaneous transformation to dissipative structures and self-organization. The forces that exist in irreversible processes create these organized states, which range from convection patterns of Benard cells to biological cycles. 

Liu M. (1994) Asymmetric phase effects and mantle convection patterns. Science 264, 1904-1907. 

Fluid flow within the melt has a crucial effect on crystal quality. If the crystal is stationary, the dominant convection pattern is upward flow of material at the crucible walls and radial flow inward at the surface (type I). Rapid rotation of crystal causes material to be thrown radially outward at the surface, and opposes the thermal convective flow (type III). These flow patterns are shown in Figure 3. In the intermediate regime, where the two flows are of comparable rates, a more complex surface pattern is observed, labeled type II. The crystal-liquid interface is convex toward the melt in type I flow and planar in type II, a condition that is used for the growth of large crystals of gadolinium gallium garnet ... 

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