Source: http://www.library.tudelft.nl/

Abstract
Previous research (e.g., Jongeling et al 2003, Hofland 2005) has shown that turbulence has an important influence on stone stability and in non-uniform flow it should be modeled explicitly. The dimensionless entrainment rate should be used to describe the bed response because of its complete dependence on local hydrodynamic conditions and independencies on time and bed material. In all studies where entrainment rate data are available, the correlation between the flow forces and the bed response still shows a high scatter level (e.g. the data of Jongeling et al (2003) and De Gunst (1999). Therefore, more experiments are needed to increase understanding of this cause-and-effect relation and to verify the available stability parameters for non-uniform flow. In this research, experiments were carried out in which both the bed response (quantified by a dimensionless entrainment rate) and the flow field (velocity and turbulence intensity distributions) are measured. The flow in a gradual expansion ope nchannel and its influence on stone stability were chosen to study as in such a flow the turbulence intensity is high. Three experimental set-ups with different expansion dimensions were used to create different combinations of velocity and turbulence. The nine-month experiment1 has resulted in a huge amount of data available. In this report the experiment arrangement and data processing methods that are employed are described and the measured data and some calculated variables are presented. The report is structured as follows. In Section 2 the experimental set-ups are described in additional to the instrumentation, hydraulic conditions and experimental procedures. Data processing methods is briefly described in Section 3. In Section 4 the measured data to determine stone parameters are presented. Finally in Section 5 the measured data and calculated variables are presented in detail.