Closure to “Discussion of ‘Establishment of the Wake Behind a Disk’” (1964, ASME J. Basic Eng., 86, pp. 880–882)

Abstract

References 1 H. Rouse, "Repartition de l'6nergie dans les zones de d6colle-

Electrostatic precipitation of airborne dust in the wake of a perforated plate

“…In the present experiments, Reynolds number falls in the range 150 < Re < 850, considerably lower than that corresponding to Carmody's (1964) data for the disc upon which we have based our quantitative eddy characteristics. Although there was no dependence observed of EgA on Reynolds number, and despite the good agreement which has been observed between theory and experiment, it is nevertheless still possible that the actual values of mean back flow velocity and mean re-entrainment velocity which characterize the eddies may not necessarily be exactly the same as those obtained by inference from Carmody's data.…”

“…Corrsin (1943) investigated the effects of the flow through a high-solidity parallel-rod grill and observed a net back flow in the wake of the solid portions extending to a number of rod diameters downstream. This, together with extensive reported information on the flow around obstacles of various geometries (Prandtl and Tietjens 1934, Carmody 1964, Fail et al 1959, indicates the formation of recirculating flow regions, or eddy pockets, on the downstream side. As a result of such eddies, according to Zhukovskii (191 l), airborne particles passing close to the edge of an obstacle experience an effective deceleration sufficient to enable other forces besides fluid mechanical (such as gravitational settling) to take over and bring about precipitation.…”

“…In the absence of such similar information for the flow around the grid, the flow around a disc is considered to be the best, if not the only, source of data for allowing a quantitative theoretical assessment of the grid case. Carmody (1964) andFail rt al. (1959), among others, have studied the flow around a circular flat disc placed at right angles to the airflow.…”