Wind Energy

10 On the Atmospheric Flow Modelling over Complex Relief 57
The finite volume method (cell centered) and a multi-stage explicit Runge-
Kutta time integration scheme are applied to the system (10.2), see [1]. The
scheme is theoretically second order accurate in space and time (on orthogonal
grids) and it also needs to be stabilized by the artificial viscosity term of fourth
order to remove a spurious oscillations from the flow-field generated by the
use of central differences for space discretization.
10.2 Definition of the Computational Case
The computational domain is 43 × 35 × 1 km long, wide and high and is
discretized by:
1) no-slip wall modelling: 150 × 100 × 16 mesh cells, horizontally uniform and
exponentially distributed in the z-axis direction, ∆zmin =4.6 m.
2) wall function modelling: 150 × 100 × 10 mesh cells, horizontally uniform
and exponentially distributed in the vertical direction, ∆zmin =28.3 m.
The other parameters are: the mean free stream velocity U =10ms −1 ,the
characteristic wall-normal domain dimension L = 1, 000 m and the corresponding
Reynolds number Re = U × L/ν =6, 7 × 10 8 , the roughness parameter
z0 = 1 m and the power law exponent 0.3 and the friction velocity
u ∗ =0.33 ms −1 are used for the inlet velocity profile, see [2], [3].
Z: 212 235 258 282 305 329 352 375
−1.03E+06
−1.04E+06
Y
−1.05E+06
−1.06E+06
−760000 −755000−750000−745000−740000−735000−730000−725000
X
Y Z
X
−720000
Fig. 10.1. The applied topography coloured by the geographical altitude (m), scale
1:1:17