Wind Energy

242 B. Stoevesandt et al.
Bin Value
10 4
10 3
10 2
10 1
10 0
Bins of Column 3
−10 0
Bin
10
Bin Value
Fig. 44.1. PDF of Windspeed change within 2 s within a 22 h measurement at Tjare
(by Böttcher, data from http://www.winddata.com)
Fig. 44.2. Typical mesh on a fx79-w-151 profile (left) and nodal points generated
(right)
44.2 The Spectral/hp Method
The spectral/hp element method combines the accuracy of classical spectral
codes with the flexibility of finite element methods (FEM). Global spectral
methods use one representation of a function u(x) by a series through the
complete domain. This idea is advanced by the spectral/hp method by subdividing
the domain into finite – unstructured – elements. This is done by
another transformation on the spectral function. To fulfill the necessary requirements,
the spectral functions of the separate elements have to be C 0
continuous.
The subdivision into a mesh in combination with the use of unstructured
meshes allows an adaption of the problem to the curved geometry and a well
tuned resolution to the flowfield.
There are two ways to achieve convergence using the spectral/hp method.
The h-type convergence refers to convergence due to a refinement of the mesh,