Experimental validation of computational fluid dynamics modeling for narrow tillage tool draft

Energy requirement of a tillage tool, mostly represented by tool draft, is a function of different soil–tool interaction components like soil parameters, tool parameters and system parameters. Soil–tool interaction modeling was conducted using computational fluid dynamics (CFD) approach considering soil as a Bingham material. Soil bin tests were conducted to validate tool draft predictions obtained from this numerical modeling. Numerical predictions and soil bin experiments for the tool draft were observed with 40 mm wide vertical tool operating at four different depths of 40, 80, 120, and 160 mm. The tool was operated at four different operating speeds of 1, 8, 16 and 24 km h⁻¹ in clay loam soil with two moisture contents of 14% and 20%. Thus, the experimental design consisted in a (2 × 4 × 4) complete randomized factorial with two replications for each test. Simulation results over-predicted tool draft in comparison to the experimental values. The difference between the predicted and measured draft were not consistent and ranged from 1% to 42%, with an average of 24% and 22% for moisture contents of 14% and 20%, respectively. The agreement of simulation data with experimental values was higher at shallow depth of operation and lower tool operating speed. The correlation coefficient between the simulation and experimental draft were found to vary from 0.9275 to 0.9914.     

g-B3C2N3: A Potential Two Dimensional Metal-free Photocatalyst for Overall Water Splitting**

Based on hybrid density functional theory (DFT) calculations, we propose a new two-dimensional (2D) B-C-N material, graphitic- (g- ), with the promising prospect of metal-free photocatalysis. We find it to be a near ultraviolet (UV) absorbing direct band gap (3.69 eV) semiconductor with robust dynamical and mechanical stability. Estimating the band positions with respect to water oxidation and hydrogen reduction potential levels along with a detailed analysis of reaction mechanism of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), we observe that g- monolayer can be efficiently used for hydrogen fuel generation over entire pH range as well as for spontaneous water splitting at basic pH range. Upon biaxial strain application, band positions get realigned along with the free energy change that is involved in HER and OER. Consequently, operational range of pH for OER gets broadened and the proposed material exhibits the ability to perform spontaneous and simultaneous oxidation and reduction even in neutral pH. The combination of pH variation and applied strain can be used as a key to control the reducing and/or oxidizing abilities precisely for diverse photocatalytic reactions to attain environmental sustainability.