We performed large-eddy simulations of the flow over an airfoil to understand the effects of leading-edge roughness designed to mimic ice accretion. The roughness elements protrude outside the boundary layer, which, near the leading edge, is very thin; thus, the configuration does not represent a classical rough-wall boundary layer, but rather the flow over macroscopic obstacles. A grid convergence study is conducted and results are validated by comparison to numerical and experimental studies in the literature. The main effect of the obstacles is to accelerate transition to turbulence. Significant variations in structure generation are observed for different roughness shapes. The three-dimensionality of the irregularities has a strong impact on the flow: it creates alternating regions of high-speed ("peaks") and lowspeed ("valleys") regions, a phenomenon termed "channelling". The valley regions resemble a decelerating boundary layer: they exhibit considerable wake and higher levels of Reynolds stresses. The peak regions, on the other hand, are more similar to an accelerating one. Implications of the channelling phenomenon on turbulence modelling are discussed.

In this study we consider the flow over airfoils with leading-edge roughness, designed to mimic the ice depositions that may occur on an aircraft in flight. The focus of this investigation is the effect of the angle of attack on the mean-flow three-dimensionality. In our previous work (Kumar et al., Journal of Turbulence, Vol. 22, No. 11, 2021, pp. 735–760), we found stationary spanwise inhomogeneities in the form of alternating regions of fast- and slow-moving fluid, which were termed “flow channels.” In the present study we investigate further this phenomenon. We observe the formation of hairpin vortices downstream of the roughness elements, which eventually merge; this causes the formation of wider channels that remain coherent and affect the trailing-edge separation. With increasing angle of attack, the intensity of flow channeling can increase or decrease depending on the topology of the leading-edge roughness. Its effect on the trailing-edge separation remains, however, significant. The mean-separation line is highly distorted, and the separation length can vary by up to 30% of the chord length along the span.

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Amongst the various types of paddy transplanters; walk-behind-type transplanters are more economically viable as compared with riding-type paddy transplanters. But, it requires more human involvement because the operator has to walk behind the two-wheel walk-behind-type paddy transplanter in puddled field conditions up to about 10-22 km during a day-long period under high temperature and humid conditions. To reduce the workload of the operator, a wireless remote-controlled system has been developed to control the various hand control levers of walkbehind-type paddy transplanter through electric linear actuators and electronic control unit. The present study emphasizes the performance evaluation of the remote control system and optimizes the machine-field parameters. Response surface methodology was used with three levels of soil puddling settlement period (4, 26, and 48 h), three forward speeds (1.40, 1.85, and 2.30 km h −1 ) in two types of soils (light-textured and medium-textured). The response factors, that is, the effective field capacity (EFC) and field efficiency (FE) were found affected by forwarding speed, soil type, and soil puddling settlement period, but no significant effect was observed at the interaction level. The optimal value of soil puddling settlement period was 26 h at a forward speed of 2.0 km h −1 for light-textured soil, whereas for medium-textured soil, it was 30 h at 1.82 km h −1 . A total saving of up to 18.18% labor requirement was observed as required in the existing walk-behindtype paddy transplanter. The increase in EFC was observed up to 20%, resulting the net benefit per unit area and per year has been increased up to 6.59% and 15.86%, respectively. The overall results of the field evaluation showed that the remotecontrolled system for the two-wheel paddy transplanter would be feasible at optimized field and machine parameters.

Environmental noise has reached an alarming level and is affecting the exposed population. The noise levels are elevated during the festival season. This study aims to explore the influence of prime festivals on noise levels in an urban area. 18 locations in the Raipur city of Chhattisgarh, India, were selected for conducting the study during the Ganesh Utsav, Dussehra, and Diwali festivals. Study of equivalent noise level (Leq) and other noise parameters Traffic noise index (TNI), Noise Climate (NC), Noise exceeding 10% and (L10) and Noise exceeding 90% of measurement time (L90) were found for all three festivals in the A-weighted decibel scale (dBA). Noise maps from observed levels were prepared using the ArcGIS Inverse Distance Weighted (IDW) interpolation method. Noise levels ranged from 61.4 to 81.3 dBA during Ganesh Utsav, 63.5 to 79.9 dBA during Dussehra, and 70.1 to 81.2 dBA during the Diwali festival. All the locations recorded above 70 dBA during Diwali, whereas nearly 50 percent of the locations recorded above 70 dBA during Ganesh Utsav and Dussehra festivals. The urgent need to control the noise pollution in the Raipur city of Chhattisgarh by making strict rules is very much needed for making the ambient environment clean, green, and healthy.