To capture the effect of initial conditions in far field evolution of momentum driven and scalar dominated Flow field, Witze scaling has been used for collapsing vector and scalar data to attain asymptotic state at self-preserving region of the jet. It incorporates the initial mass, momentum, energy to capture the effect of heating level on both near and far field development of strongly heated coaxial turbulent round air jets entering into quiescent ambient. This paper compares the effectiveness of potential core length and jet effective diameter as the length scales to collapse both mean and fluctuating components of velocity vector and temperature scalar. Similarity considerations with Witze length scale using the initial momentum flux and buoyancy flux gives a good collapse at all levels of heating.

field observations of Flow measurement difficulties using portable ultrasonic Flow meters are reported in this work. Accordingly, pipe wall thickness and sensors’ spacing were identified as two important sources of the in-situ Flow measurement inaccuracies. Experimental tests were accomplished to evaluate the effect of input parameters on the performance of the portable ultrasonic Flow meters. Iron and Unplasticized Poly Vinyl Chloride (UPVC) pipes of the outer diameters of 3, 4, and 8 inches were tested. For all tested cases, the pipe wall thickness increase would affect the ultrasonic performance more than the cases with the wall thickness decrease. A mixed effect of the sensors’ spacing was observed for the changes in pipe material/dimensions. Finally, a correction equation was proposed to improve the Flow measurements.

Introduction: The computational fluid dynamics (CFD) simulation of three-dimensional wire-plate electrostatic precipitator is performed in the present study. Materials and methods: The momentum equation, the electric potential equation and current continuity equation are solved by using ANSYS Fluent. The ion charge density at the corona is calculated iteratively using the Peek formula. The SIMPLE algorithm is used to treat the pressure-velocity coupling. The RNG k-ε model is used to describe turbulence. Results: The airFlow keeps stable away from the first corona electrode. The distribution of the electric potential is dependent on the wire-plate distance and the wire-wire distance. The potential and ion charge density increase with the increase of the wire-plate distance. With the increase of wire-wire distance, the maximum electric field strength decreases whereas the maximum ionic charge density increases. The ion charge density near the second corona electrode is relatively small. A small wire-wire distance will make the electric field concentrated around the wires. Conclusion: According to this study, the wire-wire distance and the wire-plate distance have great effect on the distribution of ion charge density and electric field strength.

The knowledge related to the methodology of the field trial study as a type of intervention studies, yet for many of our researchers is not fully understood. The aim of the current study was a better understanding of conducting this type of research. field trial studies are done on healthy individuals and aim to prevent. These types of studies such as clinical trials are performed on both individual and collective levels. One type of these studies is Community Intervention Trial which is usually done on a large scale population. field trial study should be carried out in stages, such as the formulation of hypotheses, selection of the population (reference population, study population, and sampling), measuring the baseline variables (before conducting preventive intervention), random allocation of subjects to intervention and control groups, doing interventions and measuring outcome. The methodology of field trial studies is very similar to clinical trials. The difference is that field trials are conducted on healthy individuals and aim to prevent and also the sample size required to this type of study is relatively more, and these studies are usually time consuming and costly.

This study represented results of the in-situ measurements of Flow in the Karun River for a period of one-month length in the spring season. The measurements were carried out in a station with average depth of 5 m, located approximately 120km distance from the northern head of the Persian Gulf. It was aimed to improve our understanding of Flow hydrodynamics in the Karun River. Spectral analysis of current showed a high energy in tidal frequencies which represent the tidal influence on this station. Unexpected, results from the field work show that the the maximum measured Flow was 70.6 cm/s in seaward direction, coincidence with neap tide. It was due to the high level of river discharge. In this period, the most important reasons for the change Flow direction were identified to be tide and river discharge fluctuation .Also, it is worth to mention that Harmonic Analysis of water level varations introduces M2, K1and O1 as the main tidal constituents with dominant of semi-diurnal tide at the location of observation.

Simulation and analysis of two phase Flow that crosses over tube bundles is crucial in safety analysis and design of kettle reboilers and steam generators. The geometry complexity of the tube bundle Flow field increases the difficulty of the conventional numerical analysis. One of the methods to reduce the numerical calculations cost is to use the porous media theory instead of the complete tube bundle modeling. Drag and tube bundle resistance force equations have been used in the porous media analysis. Based on available experimental results, two tube bundle arrangements have been considered. Due to existence of symmetric geometry and uniform energy source over the tube bundle, the two dimensional symmetric models have been used as well. It was observed that the predicted pressure drop in this research has acceptable adaptation with the experimental results. Meanwhile, by considering different outlet boundary conditions, calculated void fraction is compared to the experimental results and showed better accuracy than similar CFD research. It was observed that the enhancement of the tube bundle thermal power increases the void fraction in the heating area of the reboiler.