5% - eTheses Repository - University of Birmingham

Chapter 5
Fluctuating
vel f (u or v)
U=lm/s mean (f 2)
U=0.64 mean (f2 )
max E (X/H=1.25)
mean (f2 )
max (f2 )
max (f)
u-Johns
-1991
E
0.642 E
0.018
0.007
0.010
0.102
v-Johns
-1991
0.35E
0.35(0.642 )E
0.018
0.003
0.004
0.063
u,v-Nak.
-1987
{ mean u,v }
{(0. 18*0. 64)=0. 115}
0.013
0.019
0.137
Figure 18. Table of maximum fluctuating velocities u,v=f. Johns
(1991) prescribes u=E and v=0.35E where E is the turbulence energy
density in (m/s) 2 which has a peak value 0.018. We then assume a
sinusoidal distribution for the fluctuating parameters which classically
gives (f 2)max = l^H^mean. Data from Nakagawa & Nezu (1987)
gives u,v directly.