Present article reviews the early and recent developments in skid resistance measurement techniques at asphalt concrete pavement. Suitability and limitations of various methods used for capturing skid characteristics of the surface has been outlined. The harmonization of laboratory and field-testing methods has been summarized briefly. Harmonization is agreement of test outcomes reported from field as well as laboratory. Correlation analysis of various in-situ and laboratory test data has been made to maintain the better harmony of measurement either in field or in laboratory. Measurement of skid resistance in field is time consuming, labor intensive and requires use of costly, advanced and sophisticated instruments. Lab measurement lags in accuracy and still needs improvement in design and working methodology which compelled researchers for looking into modelling as an alternative option. In the subsequent sections, progress in modelling approach (analytical to numerical) has been discussed in brief. Analytical and numerical solutions of asphalt concrete pavement for modelling skid resistance have been reviewed and emphasis for choosing a particular solution has been justified on the basis of accuracy as well as efficacy of the output model. Critical factors affecting skid resistance model like hydroplaning, tire related parameters, temperature, surface texture has been highlighted in this manuscript. Skid data obtained from any model whether it is analytical or numerical, needs to be validated against field measurement or some established data. Validation of skid resistance model using field test and experimentally derived equations in various research studies has been summarized in later section of this article. Few key research directions have been suggested as scope of future study so as to predict a more reliable skid resistance model (1) For predicting dynamic frictional properties with higher accuracy at tire pavement interface, tire pavement interaction modelling still needs improvement considering all field constraints (2) Influence of surface texture, hydroplaning, temperature and pavement ageing needs to be studied in depth for modelling skid resistance as these are critical parameters & contributes significantly.

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Trailing edge and wake flows are of interest for a wide range of applications. Small changes in the design of asymmetrically beveled or semi-rounded trailing edges can result in significant difference in flow features which are relevant for the aerodynamic performance, flow-induced structural vibration and aerodynamically generated sound. The present study describes in detail the flow field characteristics around a family of asymmetrically beveled trailing edges with an enclosed trailing-edge angle of 25 ∘ and variable radius of curvature R. The flow fields over the beveled trailing edges are described using data obtained by particle image velocimetry (PIV) experiments. The flow topology for different trailing edges was found to be strongly dependent on the radius of curvature R, with flow separation occurring further downstream as R increases. This variation in the location of flow separation influences the aerodynamic force coefficients, which were evaluated from the PIV data using a control volume approach. Two-point correlations of the in-plane velocity components are considered to assess the structure in the flow field. The analysis shows large-scale coherent motions in the far wake, which are associated with vortex shedding. The wake thickness parameter yf is confirmed as an appropriate length scale to characterize this large-scale roll-up motion in the wake. The development in the very near wake was found to be critically dependent on R. In addition, high-speed PIV measurements provide insight into the spectral characteristics of the turbulent fluctuations. Based on the time-resolved flow field data, the frequency range associated with the shedding of coherent vortex pairs in the wake is identified. By means of time-correlation of the velocity components, turbulent structures are found to convect from the attached or separated shear layers without distinct separation point into the wake.@en

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