Systematic study of the effect of terrain on dynamics and turbulence of wind flow within the constant flux layer

低层大气边界层内的流动和输送现象除了受到热分层的影响外，还受到湍流的显著影响。人类所感知的微气候条件、建筑物上的风荷载或例如风力发电都受到地面风流中固有的湍流的影响。在最低层，由于地形、建筑物和地面植被的存在，风的流动非常复杂，湍流动力学仍然需要广泛的研究。原则上，现场测量以及数值模拟或流体模拟都可用于研究低大气边界层内的流动现象。然而，由于有限的空间密度和分辨率，代表性和推广的潜力，从现场测量结果是有限的，并受到不断变化的物理边界条件，通常不能完全重新编码和记录。将湍流条件推广和转换到其他位置通常需要进行一些简化和假设。此外，小尺度湍流和输运现象的数值模拟也是基于一些并不总是完全合理的假设。然而，部分涡解数值模式，如LES提供了一个更可靠的洞察地面风的动力学和湍流对运输过程的影响。然而，使用任何模型的先决条件是，它已经过特定应用的、系统的和-在物理意义上-完整的模型验证。在该项目中，通过在大型边界层风洞设施中进行专门和系统的实验室实验，研究了中等结构地形对低空风的湍流特性和动力学的影响。对大气边界层最低10%区域内的湍流进行了足够详细的模拟，并将通过最先进的测量技术进行测量，以便获得关于受不同理想化和真实的地形结构影响的湍流动量通量、流量-压力相关性和湍流质量通量等方面的系统信息，并得出不同的因果关系。测量数据预期用作已知、量化和记录质量的参考数据，满足模型验证的数据质量标准。该项目建立了一个专门的高质量数据库，目前还没有。项目内产生的数据将通过互联网以经过预处理、质量有保证和有充分文件记录的形式提供给潜在用户。

Flow and transport phenomena within the lower atmospheric boundary layer are substantially influenced, besides effects due to thermal stratification, by turbulence. Micro-climatic conditions as they are perceived by humans, wind loads on structures or, for instance, wind power production are substantially affected by turbulence inherently present in ground level wind flows. At lowest levels, wind flow is very complex due to the presence of terrain, buildings and ground vegetation, and turbulent dynamics still remains subject to extensive research. In principle, both field measurements as well as numerical or fluid modeling can be applied for the investigation of flow phenomena within the lower atmospheric boundary layer. However, representativeness and the potential for the generalization of results from field measurements is limited due to limited spatial density and resolution, and constrained by continuously changing physical boundary conditions which usually cannot be recoded and documented completely. Generalization and translation of turbulence conditions to other locations usually requires a number of simplifications and assumptions to be made. Also, numerical modeling of small-scale turbulent flow and transport phenomena is also based on a number of assumptions which are not always completely justified. Nevertheless, partially eddy-resolving numerical models such as LES provide a much more reliable insight into the dynamics of ground level winds and the impact of turbulence on transport processes. A precondition for the use of any model is, however, that it has undergone an application-specific, systematic and - in a physical sense - complete model validation. In the project, the impact of moderately structured terrain on turbulence characteristics and dynamics of low level winds is investigated by means of dedicated and systematic laboratory experiments in a large boundary layer wind tunnel facility. Turbulence within the lowest 10% of the atmospheric boundary layer is modelled in sufficient detail and will be measured by means of state-of-the-art measurement techniques in order to obtain systematic information on, for instance, turbulent momentum fluxes, flow-pressure-correlations and turbulent mass fluxes affected by different idealized and real terrain structures and to derive distinct causalities. The measured data is intended to be used as reference data of known, quantified and documented quality, fulfilling data quality standards for model validation. The project establishes a dedicated high quality data base which is not available yet. The data generated within the project will be available for potential users in a preprocessed, quality-assured and sufficiently documented form via Internet.