S T R ~ K T I ! W F .
OF I)ENSITY ISTERFACES
439
!4 -
I0
"..,
cm) D 1 2 : 1
8
6 -
4 -
2 -
, . . .
. . . . , ...
RI = 8000
Pe = 3300
R I = 300
Pe = (6,000
1.000 1.002 t.004 I.006 1.008 t.010
olbOO l . d O 4 t.dO8 I dt2
I dt6 t &O
DENSITY
DENSITY
Fic;. 4. Instantaneous protiles 01 densit). prniluced by salinity, bcrsu% dcptli for various
viilues ol' Ri and Pc.
erosion is most rapid when the Richardson number is least. The fact that the
interface thickness then remains constant with further increase in time is also
shown in Fig. 6. Visual observation with ;I shadowgraph showed that while
the erosion was taking place the ccntrc of tlie interface remained undisturbed while the edges were eroded by the turbulence. This was confirmed
by profiles such a s those I;hown in Fig. 7 where the original gradient can be
seen to exist in the centre of the interface even though the edges have been
eroded considerably.
€
I
I
1
I
u (cm/rcc)
0
0.05
0.10
0.15
020
0.25
0.30 0 5
F I G 5 . 'Thc thickness of a adinity interface plottcd against the turhulcnt velwily u. The
viilucs reprcscnl averapcs of all profiles at each value of 14 with Ap varying from
0.002 to 0.02 gm!nil.