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In this paper, the turbulents bursts triggered by the interactions between fluid and bar are investigated using the bursting events technique. The intricate association of scouring that occurred at a region upstream of the bar is reflected by the parameter Dominance Function. It is the ratio of occurrence probability of ejection events to the occurrence probability of sweep event. The results indicate that the high magnitude of scouring is observed in the interaction region of these events. (near bed region, z/h < 0.03). The parameter Dominance Function is successfully predicting the high scouring region. The linkage of deposition process which occurred at locations downstream of the mid-channel bar is signified by the parameter Bursting Index which is the ratio of summation of odd events to the summation of even events. The results indicate that the high magnitude of Bursting Index (BI ≥ 1.3) is observed at the high depositional region. The parameter Bursting Index is successfully predicting the high deposition region located downstream of bar. The effect of Submergence Ratio on the turbulent structure of flow is also investigated. The dominance of sweep and ejection events is observed at regions upstream of the mid-channel bar by analyzing the Reynolds stress contours. The high positive value of Reynolds stress is responsible for scouring at regions just upstream of the bar. The negative value of Reynolds stress is observed at regions just downstream of the bar. The velocity fluctuations are modelled using the Gram-Charlier method. The impact of bar on the turbulent flow structure is investigated by plotting the Joint Probability distribution of bursting events. For regions upstream of the bar, the turbulent burst triggered by the interaction of fluid and bar is maximum at a point located closest to the upstream end of bar. [ABSTRACT FROM AUTHOR]

Abstract Indigenous plants are widely abundant in Mauritius and if made proper use of, these renewable plants can contribute largely to the local economic sector. This paper assesses the suitability of producing eco-friendly and biodegradable papers using low-cost raw materials by means of fibre from Pandanus utilis’ leaves commonly known as ‘Vacoas’. The leaves were used along with Arundo donax or wastepaper to manufacture composite paper samples in the ratios of 20:80, 40:60, 60:40, 80:20 and 100:0. Chemical pulping was done through Kraft process for a period of 1.5 h at a concentration of 14 wt% NaOH and 4 wt% Na2S at 90 ± 2.5 °C. The mean thickness of the papers was determined to be 0.261 ± 0.027 mm. It was found that the 100% Vacoas fibres had the highest absorbency rate of 1.8 ± 0.5 s followed by the composite A. donax and Vacoas fibre (1.8 ± 0.3 s). The most abrasion resistant paper which also demonstrated the highest burst index of 0.63 kPa m2 g− 1 and tensile index 11.8 N m g− 1 was observed to be that of 100:0 Vacoas fibre paper requiring 35 turns to get abraded followed by the P. utilis and A. donax mix where the 80:20 fibre ratio revealed a high bursting index of 0.45 kPa m2 g− 1 requiring 25 turns to get abraded while 40% P. utilis and 60% A. donax had a high tensile strength of 11.9 N m g− 1. Vacoas to wastepaper mix ratios of 20:80 and 40:60 were found to have the highest mean recovery angles of 61.3 and 59.6°, respectively.

The widespread availability of banana pseudo stems which do not have considerable commercial value in the country presents a potential source of non-wood raw material for paper production. This investigation determined the suitability of using banana fiber for wrapping paper production. Banana fiber was used with sugarcane bagasse and wastepaper to produce paper in 20:80, 40:60, 60:40 and 80:20 ratios. Banana and sugarcane bagasse were chemically pulped using 12% NaOH and 4% Na 2 S for 1.5 h. The mean thickness of the papers were 0.263 ± 0.04 mm. 100% banana paper and 100% bagasse paper showed nearly similar water absorbency (2.15 s and 2.17 s) and were 2.25 times more than paper from 100% wastepaper. Highest tensile index was evidenced by banana paper with 20% wastepaper (29.4 Nm/g). For banana-bagasse mix-ratios, 20% bagasse demonstrated highest tensile index (16.04 Nm/g). 100% banana paper produced a tensile index of 18.97 Nm/g. Highest bursting index was from banana paper with 20% wastepaper mix (2.00 kPa m 2 /g). For banana-bagasse mix-ratios, 20% bagasse addition showed the greatest bursting index (0.88 kPa m 2 /g). 100% banana paper produced a burst index of 1.05 kPa m 2 /g. Highest abrasion resistance was 180 turns which was demonstrated by 100% banana paper. 20% mix bagasse and 20% mix wastepaper demonstrated the greatest abrasion resistance with 136 turns and 120 turns respectively. 20 ̶ 40% of wastepaper (5.4 ̶ 5.8% weight loss) and 10 ̶ 30% bagasse (10.0 ̶ 15.5% weight loss) were categorised as optimal mix percentages in the pulp mix for their minimal weight losses. [ABSTRACT FROM AUTHOR]