Eddy pumping

Eddy pumping Vertical water displacement caused by internal waves. 

Martin, A. P., and Pondhaven, P. (2003). On estimates for the vertical nitrate flux due to eddy pumping. Journal of Geophysical Research, Oceans 108, doi 10.1029/2003JC001841. 

Palkowski, P. G., Ziemann, D., Kolber, Z., and Bienfang, P. K. (1991). Role of eddy pumping in enhancing primary production in the ocean. Nature 352, 55-58. 

Cavitation Loosely regarded as related to water hammer and hydrauhc transients because it may cause similar vibration and equipment damage, cavitation is the phenomenon of collapse of vapor bubbles in flowing liquid. These bubbles may be formed anywhere the local liquid pressure drops below the vapor pressure, or they may be injected into the hquid, as when steam is sparged into water. Local low-pressure zones may be produced by local velocity increases (in accordance with the Bernouhi equation see the preceding Conservation Equations subsection) as in eddies or vortices, or near bound-aiy contours by rapid vibration of a boundaiy by separation of liquid during water hammer or by an overaU reduction in static pressure, as due to pressure drop in the suction line of a pump. 

Eddy Current eleetromagnets that ean experienee some slip inside the pump and may deeouple. 

Flow of the liquid past the electrode is found in electrochemical cells where a liquid electrolyte is agitated with a stirrer or by pumping. The character of liquid flow near a solid wall depends on the flow velocity v, on the characteristic length L of the solid, and on the kinematic viscosity (which is the ratio of the usual rheological viscosity q and the liquid s density p). A convenient criterion is the dimensionless parameter Re = vLN, called the Reynolds number. The flow is laminar when this number is smaller than some critical value (which is about 10 for rough surfaces and about 10 for smooth surfaces) in this case the liquid moves in the form of layers parallel to the surface. At high Reynolds numbers (high flow velocities) the motion becomes turbulent and eddies develop at random in the flow. We shall only be concerned with laminar flow of the liquid. 

Tchobanoglous, G. (ed.) (1981), Occurrence, effect and control of the biological transformations in sewers. Chapter 7 in Metcalf and Eddy, Inc., Wastewater Engineering Collection and Pumping of Wastewater, McGraw-Hill, New York, pp. 232-268. 

The mechanism of transfer of solute from one phase to the second is one of molecular and eddy diffusion and the concepts of phase equilibrium, interfacial area, and surface renewal are all similar in principle to those met in distillation and absorption, even though, in liquid-liquid extraction, dispersion is effected by mechanical means including pumping and agitation, except in standard packed columns. 

One of the most important processes involved in the scale-up of liquid parenteral preparations is mixing [1]. For liquids, mixing can be defined as a transport process that occurs simultaneously in three different scales, during which one substance (solute) achieves a uniform concentration in another substance (solvent). On a large, visible scale, mixing occurs by bulk diffusion, in which the elements are blended by the pumping action of the mixer s impeller. On the microscopic scale, elements that are in proximity are blended by eddy currents, and they 43... 

Recently, one of the most practical results of these studies has been the ability to design pilot plant experiments (and, in many cases, plant-scale experiments) that can establish the sensitivity of process to macroscale mixing variables (as a function of power, pumping capacity, impeller diameter, impeller tip speeds, and macroscale shear rates) in contrast to microscale mixing variables (which are relative to power per unit volume, rms velocity fluctuations, and some estimation of the size of the microscale eddies). 

Gibb, L.E. Eddy, A.A. (1972). An electrogenic sodium pump as a possible factor leading to the concentration of amino acids by mouse ascites-tumour cells with reversed sodium ion concentration gradients. Biochem. J. 129, 979-981. 

Metcalf Eddy, Inc. (1981). Wastewater Engineering Collection and Pumping of Waste-water. McGraw-Hill, New York. 

Those who prepare and/or manufacture LC columns must use the above methods to limit the effects of eddy diffusion on the chromatographic separations. However, there are practical limitations. Column and stationary-phase particle diameters can only be reduced to points that are compatible with the pressure limitations of the pumps used in chromatographic instruments and the required sample capacities of the columns. The degree of training and experience of those who pack the columns may also limit the quality of the procedure used in packing the column. Nevertheless, most commercial manufactur-... 

The axial impeller discharges fluid mainly axially, parallel to the impeller shaft. The fluid is pumped through the impeller, normally towards the bottom of the tank. Since the flow make a turn at the bottom, the velocity vectors fan out radially at approximately D/2 beneath the impeller. Then, the flow moves along the bottom and rises near the tank wall. Analyzing the flow pattern, one can see that a back-flow eddy region is formed directly under the impeller. Upon examining the flow around the axial impeller one can also observe that a large contribution to the inlet flow enters radially at the tip of the impeller blade. This pattern is shown in Fig 7.1. 

Lo [51] simulated two- and three phase isothermal non-reacting stirred tanks with two downward pumping 45o pitched -blade disc turbines and one curved-blade impeller at the bottom. Four or six baffles were placed at equal distance around the vessel wall. An Eulerian multiphase-population balance (MUltiple-SIze-Group, MUSIG) model was used as implemented in CFX. Turbulence of the continuous phase was modeled by the standard k-e turbulence model, and an algebraic relation was used for the particle induced eddy vis-... 

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