Wind Energy

244 B. Stoevesandt et al.
Fig. 44.4. u-velocity at time variable boundary conditions (left) and suspicious
pressure output (right) throughout the domain
44.4 First Results
The 2D simulation worked well under stationary inflow. As the boundary conditions
were set to periodic changes of the inflow boundaries, some difficulties
were encountered. Obviously the calculation process in Nektar is working for
the velocity flows (see Fig. 44.4 left). Therefore the general process of solving
the problems seems to be working well. Nevertheless the pressure output
shows relatively high pressure variations (Fig. 44.4 right). As the force on the
profile seems to be in the same order as for the stationary calculation, the
general calculation is obviously correct. These results are in need of further
verification.
44.5 Outlook
In a first step the pressure calculation for the time variable boundary condition
has to be improved. Especially for simulating variable inflow it seems to
be reasonable to implement a new way to establish time variable boundary
conditions into the code. Since so far the time variability is limited to continuous
functions, it seems convenient to create a more flexible code for time
variable inflow.
As so far only the 2D-DNS code has been tested, all the further extension
have to be implemented in the 3D- and Fourier-LES code. As DNS is slow,
simulation has been done so far for low Reynolds numbers only.
References
1. Amandolese, X., Szechenyi, E.: Experimental Study of the Effect of Turbulence
on a Section Model Blade Oscillating in Stall. Wind Energy 7: 267–282, 2004
2. Karniadakis, G. E. and Sherwin, S. J.: Spectral/HP Element Methods for CFD.
Oxford University Press, Oxford, 1999