Shape Optimization of an abrupt contraction using numerical streamlining

This research was conducted to find a reliable technique to shape an abrupt contraction for minimizing the energy loss. The method may find broader applications in design of variety of transitional cross-sections in hydraulic structures. The streamlines in a 2-D contraction were calculated through solving the potential flow equations in rectangular and curvilinear coordinates. The natural cubic spline equations were applied to approximate the shape of streamlines. The streamlines close to the solid boundary, usually those that represent 5 and 95 percent of the discharge, were repeatedly mapped onto the solid boundary in a trial and error procedure until a negligible difference between two consecutive shapes was achieved. This procedure was applied through a code developed in C++, namely Streamlining Program Code or SPC. The initial and final shapes were used to validate SPC by the help of a robust CFD software, OpenFOAM. In a 2-D contraction with contraction ratio of 5, entrance velocity of 1 m/s and outlet pressure of atmosphere (P = 0 pa), the maximum spatial difference between the stream lines found by the code and OpenFOAM was limited to 2.74% that occurred in the entrance of the contraction. Finally, according to the validation, the streamlining technique and the code could successfully applied to shape optimization of hydraulic structures

Removal of cadmium from contaminated soil using iron (III) oxide nanoparticles stabilized with polyacrylic acid

The aim of this study is to evaluate the effect of Fe3O4 nanoparticle, stabilized with polyacrylic acid on cadmium removal from the contaminated soils. To investigate the effect of important parameters, including nanoparticle concentration, pH, contact time, and the ratio of contaminated soil mass to nanofluid volume, several batch tests were performed. The maximum removal rate (100%) of cadmium was obtained in the following conditions: nanofluid concentration = 500 ppm, pH = 6.5, contact time = 24 hr and the ratio of contaminated soil mass (gr) to nanofluid volume (mL) = 1:150. Results of selective sequential extraction tests showed that the distribution of cadmium in different fractions of the soil was carbonates, oxides and hydroxides, residual fraction, exchangeable, and organic matter respectively. The tendency of nanoparticles for removal of Cd2+ from the soil fractions was in the order of: exchangeable > carbonates > oxides and hydroxides > organic matter > residual

Phosphorus migration in an unconfined aquifer using modflow and Mt3dms.

The rapid rate of urbanization and increasing demand for water in agriculture and industry are the reasons for considering groundwater as a main source of water. This can be a prologue to contamination of groundwater. Phosphorus as a type of nutrient that is derived from fertilizers has adverse effect on surface and subsurface water. The aim of this study was to monitor groundwater quality and the fate of contamination via three dimensional finite-different groundwater flow simulation (i.e. Visual MODFLOW version 4.2.). The study area was the campus of University Putra Malaysia. The monitoring indicated that the concentration of phosphorus is higher than those imposed by the standard of the Malaysian Department of Environment (DOE). Results of contamination transport modelling revealed the different rates of phosphorus transport in layers at the end of simulation period

Mechanical Behavior of Concrete, Made with Micro-Nano Air Bubbles

Nano materials have been widely used in laboratory and industrial scales in order to improve various properties of concrete and concrete mixture. The mainstream practice of the researches in this field is to add metallic nano-particles into the concrete mixture. The present research focuses on adding Micro-Nano Air Bubbles (MNAB) into water before mixing it with aggregate and cement mixtures. It studies the compressive and tensile strength as well as other engineering properties of the concrete such as the initial and final setting time and the variation in temperature during the setting. The ratio of water/cement was 0.6 with three specimens, prepared for each mixed design to ensure the data quality. Results showed that MNAB-made concrete had 19% higher compression and 16% tensile strength, while the initial and final setting times were significantly shorter (approximately a half) and hydration temperature was notably lower than ordinary concrete