• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.11 no.1
• /
• pp.57-70
• /
• 2007

The effects of variable viscosity, blowing or suction on mixed convection flow of a viscous incompressible fluid past a semi-infinite horizontal flat plate aligned parallel to a uniform free stream in the presence of the wall temperature distribution inversely proportional to the square root of the distance from the leading edge have been investigated. The equations governing the flow are transformed into a system of coupled non-linear ordinary differential equations by using similarity variables. The similarity equations have been solved numerically. The effect of the viscosity temperature parameter, the buoyancy parameter and the blowing or suction parameter on the velocity and temperature profiles as well as on the skin-friction coefficient and the Nusselt number are discussed.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1034-1039
• /
• 2008

Recently, the sludge suction collector is preferred rather than the scraper type sludge collector due to enhancement of the clarifier efficiency. The sludge suction collector is usually operated by the user's experience without any scientific and technical consideration. There are many factors that should be considered for higher quality of discharged water and stabilized flow in the rectangular sludge suction collector but, the optimal design on the inflow channel and orifices connecting with the inflow channel is needed for similar flow rates at the orifices. The 4 cases of channel geometry are considered and mass flow rates of each case at the orifices are evaluated using Computational Fluid Dynamics applied VOF(Volume of Fraction) model.

• Korean Journal of Acupuncture
• /
• v.28 no.3
• /
• pp.141-150
• /
• 2011

Objectives : The aims of this study were to evaluate a blister caused by cupping. Methods : We searched relevant case reports, survey, and review articles using databases of online bibliography. Results : 1. The fluid in the blister caused by cupping therapy is normal substance by laboratory analysis. The fluid has no signs of infection in the culture, Gram stain, or tissue biopsy 2. In histological finding, the blister caused by cupping therapy is made by dermo-epidermal seperation at subcellular level. Suction blistering was neither inflammatory nor autolysis activation of lysosomal hydrolases. 3. Blistering times directly, related to suction pressure. Suction blister formation time is accelerated in older subjects compared with younger individuals and higher temperature was more susceptable to the blister compared with lower temperature. The flexor aspect of forearm is a easy site for suction blister formation compared with leg and abdominal site. 4. Blister caused by cupping therapy is treated by regular and judicious changes of sterile dressing over several weeks. The vesicles healed well and left no visible scar. Conclusions : Blister caused by cupping therapy is artificially controlled by doctor's therapeutic purpose. Blister is not histologically injurious to health and the blister is a natural concomitant after cupping therapy.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.7
• /
• pp.2945-2950
• /
• 2011

As the step to improve fuel efficiency, there is the system to build up the eddy of combustion chamber at the suction line in order to increase the combustion efficiency. The models installed with no vortex generation system or with various shapes of the system are examined by fluid analysis. Vortex generation system is installed prior to the suction of combustion chamber. The wing of this system winds itself around the suction air and generates the vortex. This study investigates the flow of suction air and the pressure distribution of suction stroke by using the eddy generation system.

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.8
• /
• pp.1201-1207
• /
• 2008

Numerical analysis information will be very useful to improve fluid system. General information about an internal gas flow is presented by numerical analysis approach. Relating with hydrogen compressing system, which have an important role in hydrogen energy utilization, this should be a useful tool to observe the flow quickly and clearly. Flow characteristic analysis, including pressure and turbulence kinetic energy distribution of hydrogen gas coming to the cylinder of a reciprocating compressor are presented in this paper. Suction-passage model is designed based on real model of hydrogen compressor. Pressure boundary conditions are applied considering the real condition of operating system. The result shows pressure and turbulence kinetic energy are not distributed uniformly along the passage of the Hydrogen system. Path line or particles tracks help to demonstrate flow characteristics inside the passage. The existence of vortices and flow direction can be precisely predicted. Based on this result, the design improvement, such as reducing the varying flow parameters and flow reorientation should be done. Consequently, development of the better hydrogen compressing system will be achieved.

• Journal of applied mathematics & informatics
• /
• v.26 no.1_2
• /
• pp.161-176
• /
• 2008

The effect of variable viscosity on MHD mixed convection Hiemenz flow over a thermally stratified porous wedge plate has been studied in the presence of suction or injection. The wall of the wedge is embedded in a uniform Darcian porous medium in order to allow for possible fluid wall suction or injection and has a power-law variation of the wall temperature. An approximate numerical solution for the steady laminar boundary-layer flow over a wall of the wedge in the presence of thermal diffusion has been obtained by solving the governing equations using numerical technique. The fluid is assumed to be viscous and incompressible. Numerical calculations are carried out for different values of dimensionless parameters and an analysis of the results obtained shows that the flow field is influenced appreciably by the magnetic effect, variable viscosity, thermal stratification and suction / injection at wall surface. Effects of these major parameters on the transport behaviors are investigated methodically and typical results are illustrated to reveal the tendency of the solutions. Comparisons with previously published works are performed and excellent agreement between the results is obtained.

• The KSFM Journal of Fluid Machinery
• /
• v.9 no.3 s.36
• /
• pp.36-43
• /
• 2006

Recently, micro hydropower and it's useful utilization are taking a growing interest as a countermeasure of global worming by carbon dioxide and exhaustion of fossil fuel. The purpose of this study is to investigate the possibility of extracting micro hydropower wasted by a valve in water supply system using micro cross-flow hydraulic turbine. In order to fulfill the functions of controlling flow rate and pressure in substitute for the valve, air and water are supplied into an air suction hole which is installed on the side wall of micro cross-flow hydraulic turbine. The results show that in case of supplying a lot of air into the air suction hole, about 50% of flow rate and relatively high value of loss coefficient are controlled by the turbine. Moreover, including high possibility of applying the micro cross-flow turbine to water supply system, extended application of the turbine to the water discharge system of drainage and irrigation canal.

• The KSFM Journal of Fluid Machinery
• /
• v.13 no.6
• /
• pp.51-56
• /
• 2010

A numerical simulation is carried out to investigate the effect of flow rate variation and performance characteristics of double-suction centrifugal pump. Two types of pump which have different impeller inlet breadth and curvature of the shroud line consist of six blades impeller and shroud ring. Finite-volume method with structured mesh and $k-\omega$ Shear Stress Transport turbulence model was used to guaranty more accurate prediction of turbulent flow in the pump impeller. Total head, power and overall efficiency were calculated to obtain performance characteristics of two types of pump according to the variation of flow rate. From the results, impeller having smooth curve along the shroud line obtained good performance. The lower flow rate, the more circulation region, flow unsteadiness and complicate flow pattern are observed. Complicated internal flow phenomena through impellers such as flow separation, pressure loss, flow unsteadiness and performance are investigated and discussed.

• International Journal of Fluid Machinery and Systems
• /
• v.4 no.1
• /
• pp.209-216
• /
• 2011

The flow upstream of a centrifugal pump impeller has been investigated by both experimental test and numerical simulation. For experimental study, the flow field at four sections in the pump suction is measured by using PIV method. For calculation, the three dimensional turbulent flow for the full flow passage of the pump is simulated based on RANS equations combined with RNG k-$\varepsilon$ turbulence model. From those results, it is noted that at both design lo ad and quarter load condition, the pre-swirl flow whose direction is the same as the impeller rotation exists at all four sections in suction pipe of the pump, and at each section, the pre-swirl velocity becomes obviously larger at higher rotational speed. It is also indicated that at quarter load condition, the low pressure region at suction surface of the vane is large because of the unfavorable flow upstream of the pump impeller.

• The KSFM Journal of Fluid Machinery
• /
• v.16 no.2
• /
• pp.27-34
• /
• 2013

As the operating range of centrifugal pump is expanded recently, the various suction conditions are demanded. The most important problem in the suction conditions is cavitation. In this study, to analyze the characteristics for such the cavitation, first the validity of the numerical analysis was certified through comparison with the experimental result of performance curve according to flow rate for the industrial centrifugal pump. At this time, the transient numerical analysis for the full type model of the centrifugal pump was performed to get more accurate results. The numerical analysis on the cavitation of centrifugal pump were conducted on the two-phase flow as the same method of one-phased flow.