256
K
+
0
z. Z A R ~
2.0
- 1.8
- 1.6
- 1.4
- 1.2
1
- 1.0 ji
V
-ae
-0.6
- 0.4
- 0.2
D
0
0
0
a t + + +
VX
$ 0 . 0
do
o
+ +
X
0
X
xo
1
0
c
0
I
I
1
1
I
I
I
1
Y+
I
20
40
60
80
Fio. 4. Distributbna of thc rmr valws of the Z,. (K,,,,,), and the velocity derivative (K'),
conditionally averaged for thc positive and the negative valws of u - Urn,,. 0, (K&)+;
0 , (K&) - ; +. (K')' ; x I (K') -.
intermittent phases arc diffcrent from each other and also that they are
dependent on the distance from the wall Y+. After some preliminary
analysis we set the critical level of Z,, which switches on the intermittency
function at an r m s value corresponding to a given intermittent phase
-( K&
for the ejections and (K&)- for the inrush phases. Another
delicate matter is whon the intermittency function is switched off [ l ( t ) = 01.
After preliminary analysb we programmed the intermittency function to
remain switched on until
where K is the rrns value of the whole signal, Md
where the (K,) value corresponds to the given intermittent phase.
1. - Urnpi < 2 K
I I < 0.3