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This paper presents an investigation of numerical simulation for a dilute particle laden flow (laminar) over in-line tube banks. Particles behavior of two different sizes and density (100 μm sand and 40 μm fly ash) is demonstrated through the present study for a fixed geometry and flow condition, that is, a square in-line tube bank of two rows deep with pitch-to-diameter ratio of two at Reynolds number 400. Dilute particulate flow assumption is used and the drag force is considered as the only external force term that affects the particles behavior in the flow. Experimental rebounding data and semiempirical equation for the erosion estimation are used. It was found through the present simulation that the particles behavior of the different sizes and density in tube bank system is quite different in their trajectories, impact and the erosion pattern. The protective role of the first row of cylinders could be supported with respect to the particles collision on the cylinder but not necessarily to the erosion point of view. Also the information at impact such as the impact velocity and the impact angle which affect the erosion (Tabakoff et al., 1988) can be estimated by using the numerical simulation shown in the present study.

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Adequate visibility through the automobile windshield is of paramount practical significance, most often at very low temperatures when ice tends to form on the windshield screen. But the numerical simulation of the defrost process is a challenging task because phase change is involved. In this study numerical solution was computed by a finite volume computational fluid dynamics (CFD) program and experimental investigations were performed to validate the numerical results. It was found that the airflow produced by the defrost nozzle is highly nonuniform in nature and does not cover the whole windshield area. The nonuniformity also severely affected the heating temperature pattern on the windshield. The windshield temperature reached a maximum in the vicinity of the defroster nozzle in the lower part of the windshield and ranged from 9~31°C over a period of 30 min, which caused the frost to melt on the windshield. The melting time was under 10 minutes, which satisfied the NHTSA standard. The numerical predictions were in close agreement with the experimental results. Thus, CFD can be a very useful design tool for an automobile HVAC system.

Numerical simulations were conducted to investigate the performance characteristics of bleed through normal slots and its effect on the turbulent boundary layer development under zero and strong adverse pressure gradient caused by incident oblique shock. The solution to the compressible Navier-Stokes and k-e equations was obtained in a domain that includes the regions inside the bleed slot and plenum in addition to the external flow. The computational results demonstrate the interactions between the plenum, and bleed flow and the effect of incident shock on the boundary layer development downstream.The computed results agree with the experimentally measured pitot and static pressure distribution inside the slot. The bleed mass flow without incident shock was underpredicted over the range of plenum pressures.The computations predicted the measured increase in bleed mass flow with incident shock.

The present study deals with the characterization of extracted dissolved gas from water in terms of its oxygen concentration and the total amount of gas extracted. This topic has long been the interest from scuba divers because the extracted dissolved gas is believed to have higher oxygen concentration due to the higher solubility of oxygen in water than that of nitrogen. However, the study results on the actual extraction of dissolved gas from water are rare. In the present study, a degassing process based on micro-vapor-bubble diffusion is proposed to demonstrate the availability of dissolved gas mixture of higher oxygen content than the standard atmosphere. A genuine experimental apparatus featured by micro-vapor-bubble generation along with a gas collector hood is prepared for the present study. The captured gas under a lower pressure then is reverted to atmospheric condition for the volume and the oxygen concentration measurements. Two test case results, one for depressurization only and the other for depressurization with micro-vapor-bubble diffusion, are presented to demonstrate the effectiveness of the latter which showed superior extraction performance. The proposed process based on micro-vapor-bubble diffusion seems promising and is expected to find practical applications not only in life science, food and beverage industry, but also in transport safety fields to mention a few.