296
W. W. WILLMARTH AND 5. S. LU
Measurements of sampled but unsorted values of ( u v ) at greater distances
from the wall (both downstream and to the side of the u, wire) show that the
magnitude of the peak in the wall or spanwise at a fixed downstream dstion from the u, win. The
decrease in magnitude of the peak is also obrlarvr#l as one travels downstream at a fixed distance &om tbc wall. From those more extensive measurcments of (uu)/TiB (aee Lu and Willmarth, 1972)it is apparent that the burst
events am confined to a narrow region in tbc 8panWioe direction near
the wall and downstream from the u , , wire.
I
I
I
(a)
FIG. 6. Convection and decay olwnpled sorted Rcyndcb ctrt~~. (uu,)/&,
with sampling
conditions of uw/uL = + 1, positive slope; y/&* r 0.169, r/&* p: 0, and U, 1 20 R/s; (a)-(e)
same as Fig. 5 (with permhion of J . Fluid Mcck.).
The convection of sweep related events detected with the sampling criterion that u, = 6 with p f t i v e slope was a h studied. The sampled sorted
Reynolds stress from swatps (uu,)j%i7 arc displayed in Fig. 6 in the same
format as used for Fig. S and at the same dintmas downstream and from the
wall. The behavior of t b tdagnftude ofthe pssfr in of the burst events; it dcasescs tts OM! travdu outward from the wall or
downstream at a fixed distance from the wall. Tha specd of convection of the