78
P. Liu
gradient and mean velocity gradient is obtained as follows:
∂u
i
∂ x j
≈
V t
l t
Ret
1/2
,
∂u i
∂ x j
≈
V t
l t
,
∂u
i
∂ x j
≈
∂u i
∂ x j
Ret
1/2