Wind field simulations at Askervein hill - WindSim

ε
t
= ε p
Here
by:
K
⎛
⎜
U
=
⎝ C
β =
τ
µ
C
2
⎞
⎟ , Y is the normal distance of the first grid point from the wall, and β is given
⎠
µ
( ε ) ( )
−1
p
C
p3
K
2
C
- C
2
p1
- C
p2
which yields a value of β=0.25.
Non equilibrium log-law wall functions
This law uses the root of the kinetic energy
characteristic length scale.
Thus, equation (1) is replaced by :
k rather than the friction velocity as the
U k
U
2
r
2
τ
2
Et
k y
= ⎛ ⎝ ⎜ ⎞
ln ⎟
κ ⎠
t
where
κ
t
= κ C
µ
E
EC
0.
25
t
=
µ
0 . 2 5
The equations (2) to (5) remain unchanged. The value of k at the near wall point is calculated
from its transport equation, considering that energy diffusion is set to zero to the wall.
For the2-scale k-ε model, the treatment is similar to that employed for the standard k-ε model,
with k p and k t determined from their respective balance equations and for simplicity it is
assumed that ε p =ε t .
2.3.2.3. Other boundaries
On the lateral sides and on the top of the domain are imposed zero normal derivatives and
zero values for velocities, k and ε. At the outlet, zero gradient boundary conditions are
imposed, meaning that plane geometry downwind the domain is assumed. Pressure is set to be
equal to zero.
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