Daniele De Wrachien

Computational Fluid Dynamics (CFD) Picture of Water Droplet Evaporation in Air

The study of droplet evaporation is applied to many and varied fields: the present approach is oriented to sprinkler irrigation. This paper examines a parametric study on the evaporation in air of a single droplet, with the aim of highlighting the influence of each parameter alone on the evaporative process. Four parameters are investigated:air temperature, droplet initial velocity, droplet initial diameter, diffusion coefficient of vapour in air. Droplet evaporation is studied through numerical-CFD simulation employing STAR-CCM+ version 5.04.012 software, which treats the evaporative phenomenon hypothesizing quasi-steady conditions, given the interface low liquid-gas vapour concentration gradients. The results are provided as time- and space-dependent in-percentage evaporation rates, the latter ones after defining a specific distance, from the injection point, to be covered. Apart from a qualitatively predictable effect of air temperature and diffusion coefficient of vapour in air, droplet initial velocity and above all droplet initial diameter prove not at all to be negligible when managing an irrigation process, the latter being inversely proportional to droplet mass evaporation. These results prove that droplet evaporation is a complicate fluid dynamic effect and cannot be simply regarded as a diffusive process. The final discussion provides some practical remarks useful to irrigation operators.

Theoretical and Experimental Analysis of Spray Flow and Evaporation in Sprinkler Irrigation

This paper shows the main results,reached during the last three years ofresearch by this group, on sprinklerirrigation modeling and experimenting. Amathematical method based on the SecondPrinciple of Dynamics proves to fully matchthe results obtained by more complicatedmodels from other authors, but still needsfurther verification to determine aerialwater droplet evaporation, even if this nowhelps to confirm the relevance of airfriction in the process. The experimentalactivity performed also shows its use inhelping towards a fuller understanding ofwater waste in sprinkler irrigationpractice.

WATER DROPLET TRAJECTORIES IN A SPRINKLER SPRAY FLOW: THE CLASSIC VERSUS QUANTUM AND SINGLE VERSUS MULTI-DROPLET PICTURES

One of the most challenging modelling problems in modern engineering is that of a particle crossing a continuous phase (air). In sprinkler irrigation practice this may refer to a water droplet travelling in air from the nozzle to the ground. The challenge mainly refers to the diffi culty in designing and solving the system of governing equations for that very complicate process, where many non-linearities occur when describing the relations and dependences among the parameters that rule the phenomenon. The problem becomes even more complicated when not just a single droplet alone is assessed but a multi-droplet system is accounted for. In addition to the inter-parameter dependencies, an inter-droplet reciprocal connection is also observed, mainly due to electrical interactions between the hydrogen and the oxygen atoms of the different water molecules. An alternative to traditional classic approaches to analyse water droplet dynamics in sprinkler irrigation has been recently proposed in the form of a quantum approach, but the whole classic-quantum and single-droplet versus multi-droplet alternatives need to be discussed and pinpointed which are among the main aims of the present paper which focuses on the theoretical part of the issue, thus highlighting the new perspectives of a deeper comprehension in the spray fl ow related phenomena.

Water drops kinematic analysis: the classic-quantum and single-multiparticle viewpoints

One of the most challenging modelling problems in science is that of a particle crossing a gaseous mean. In sprinkler irrigation this applies to a water droplet travelling from the nozzle to the ground. The challenge mainly refers to the intense difficulty in writing and solving the system of governing equations for such complicate process, where many non-linearities occur when describing the relations and dependences among one influential parameter and another. The problem becomes even more complicate when not just a single droplet alone is assessed but a multi-droplet system is accounted for as, in addition to the inter-parameter dependencies, it is also observed an inter-droplet reciprocal affection, mainly due to electrical interactions between the hydrogen and the oxygen atoms of the different water molecules. An alternative to traditional classic approaches to analyse water droplet dynamics in sprinkler irrigation have been recently proposed in the form of a quantum approach, but the whole classic-quantum and single-droplet versus multi-droplet alternatives need to be discussed and pinpointed and these are among the main aims of the present paper which focuses on the theoretical part of the issue, thus highlighting the new perspectives of a deeper comprehension in the spray flow related phenomena.

The Role of Metal Ions in Protein and Fatty Acids Biosynthesis in Soybean under Micronutrients Application to Soil

The present study is part of our ongoing investigation to study the role of trace elements on soybean seed composition (protein, oil, and fatty acids). This study was conducted to study the effects of five trace elements (Mn, Cu, Zn, Mo, B). The treatments of Mn, Cu, Zn, Mo, and B were chlorides, except Mo as oxide, and B as boric acid. The treatments were Mn, Cu, Zn, Mo, and B alone and in combination with the chelating agent citric acid (CA), for example Mn + CA, Cu + CA, and Zn + CA. Soybean cultivar (Bolivar with maturity group V) was grown in a repeated greenhouse experiment in a randomized complete block design. The compounds were applied to three-week-old soybean plants at V3 (vegetative) and at R3 (beginning of seed-pod initiation) stages. The plants were allowed to grow until maturity under greenhouse conditions. The harvested seeds were analyzed for mineral, protein, and fatty acid contents. Results showed that Mn, Cu, and B treatments increased seed protein, while Zn, Mo, Cu + CA, and B + CA decreased the protein. Treatments of Zn, Mo, CA, Cu + CA, Zn + CA, Mo + CA, and B + CA increased the oil. Treatments of Mn and Cu decreased the oil. The Cu and B treatments increased oleic acid by 8.0% and 7.4%, respectively for Cu and B. Treatments of Mn, Mo, CA, and Mn + CA, Cu + CA, Zn + CA, Mo + CA, and B + CA decreased oleic acid by 0.6% to 14.4%. Treatments of Cu, Zn, Mo, B, CA, Mn and their combination with CA increased linoleic acid by 1.3% to 6.5%. Our goal was to identify the trace elements that would make desirable alteration in the seed composition qualities.