ESDU 01008:2010
$191.10
Computer Program for Wind Speeds and Turbulence Properties: Flat or Hilly Sites in Terrain with Roughness Changes
| Published By | Publication Date | Number of Pages |
| ESDU | 2010-11 | NA |
PURPOSE AND SCOPE
For strong winds (neutral atmosphere), estimation methods are
provided in ESDU 82026, 83045, 85020 and 86010 giving the variation
of hourly-mean wind speed, gusts, intensities of turbulence and
integral length scales and spectral densities of turbulence with
height over terrain with roughness changes. For convenience, tables
of wind speed factors and properties of the u-component of
turbulence based on these methods are presented in ESDU 84011,
84030 and 86035 for various combinations of ground roughness at the
site and upwind.
The computer program used to generate the data for these simple
look-up tables has been extensively modified for more general use
and expanded to include topographic effects. A number of features
have been added to the program to assist practical application. In
particular, the program has now been converted to Visual Basic and
is run as a module in Microsoft Excel 97 (or later) using a
spreadsheet format for entering data and printing the resultant
output.
A major modification to the previous version (A9232) is that
topographic effects are now computed via a program based on the
theoretical model of Deaves rather than on a simplified model which
could only be applied conveniently to isolated hills. The program
can be used to calculate wind speeds over hilly terrain which may
consist of several peaks and troughs. It has also been adapted to
provide estimates for steep terrain where flow separation effects
occur. Also included is a simplified method for the distortion
effect of topography on turbulence.
The user is recommended to use Tables 3.1 and 3.2 which
provide a summary and guidance for the input data
required. The rest of this document supplies more detailed
information concerning the input data (cross-referenced in Tables
3.1 and 3.2), the use of the program, an example and the basis of
the methods used.
The main features of the program are listed in Section 2.1 and
the installation and setting up of the program is described in
Section 3. A description of the input and output data formats is
given in Sections 4 and 5 and a summary of the basis of the methods
used is described in Section 6. Examples of the use of the program
are given in Section 7 and comparisons with two sets of full-scale
measurements on hills are given in Section 9.
Other programs which perform some of the same tasks as the
program given in this Item have been included previously in ESDU
84011 and 85003. These programs will give values of wind speed and
turbulence intensity (Iu) to within a few
percent (typically less than 5%) of the values given by the present
program for a single roughness change. However, the present program
has a more definitive source (see Section 6) and is likely to be
more reliable in general application. It is also more comprehensive
and has a research and application role in providing a means of
correcting measured data to specified standard conditions.
The application of the neutral atmosphere model to tropical
storms such as hurricanes and typhoons is discussed in ESDU 87034.
It is reasonable to expect that over land the program can be used
for such storms at heights below 200 m.