• Archives of Craniofacial Surgery
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• v.14 no.2
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• pp.102-106
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• 2013

Background: When using the anterior approach for performing superficial parotidectomy, the first thing to do is to find the buccal branch of the facial nerve and the parotid duct. The buccal branch usually runs transversely with the parotid duct from the anterior border of the parotid gland. We wanted to check the relationship between the two structures during the operation and to get clinically helpful information. Methods: Twelve patients with parotid mass were treated with superficial parotidectomy between May 2012 and August 2012. The outline of superficial and deep lobes of the parotid gland, parotid duct, and the buccal branch of the facial nerve were drawn on the transparent film by tracing the structures intraoperatively. Results: In 7 (58.3%) of 12 cases, the buccal branch of the facial nerve was located more caudally than the parotid duct at the anterior border of the superficial lobe of the parotid gland. In 3 cases (25%), the buccal branch was located more cephalically than the parotid duct. The mean distance between two structures were $2.54{\pm}1.48$ mm. In 11 cases, the parotid duct was located deeper than the buccal branch. Conclusion: The buccal branch of the facial nerve tends to be located more caudally than parotid duct and runs more superficially than parotid duct in all cases. We identified the relationship between the parotid duct and the buccal branch of the facial nerve during the operations on living subjects, not from the cadavers, so it would be a clinically helpful study which supplied more accurate anatomical information.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.4
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• pp.1416-1425
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• 1996

A numerical method has been proposed to predict 3-dimensional flow in a duct system with multiple outlets. For the duct system, it is supposed that the pressure values are given at multiple outlets while the velocity profile is given at a inlet. To maintain the continuity of pressure distribution between main and branch duct, present method allows that the pressure value taken from analysis of branch duct can be converted to the main duct analysis. The result from present method which can handle the pressure boundary condition closely coincided with that from regular method which can handle the velocity boundary condition only. Furthermore the flow distribution from present method showed good agreement with that from the single block method. From the comparison of the present method with the total pressure method used for engineering duct design, 13% of discrepancy in pressure loss was shown between the main duct inlet and the branch duct outlet.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.67-74
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• 2005

Fluid flow and heat transfer in rectangular duct system are measured and computed by commercial software of Star-CD for comparison between them. Three rectangular systems are investigated in this study. Those are a rectangular duct with 90 degree bended elbow, a rectangular duct with two branchs, and a circular cylinder in a rectangular duct. But heat transfer is studied only for last system. These investigations show us that the numerical solutions predict satisfactorily design factors (K-factor for the elbowed duct, distributions of flow rates into each branch from a duct, and Nusselt number around circular cylinder) even though there are some disagreements in velocity profiles and turbulent kinetic energy.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.2
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• pp.211-217
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• 2006

This study is focused on the analysis of the characteristics of marine HVAC duct. These results will be applied to develope a robot which is for maintaining a cabin comfort, convenience and healthy through HVAC duct. The followings are the results of this study. (1) The evaluated items which proposed by at the view point of robot's function can be adapted to other vessels for the same purpose, (2) For the case of round type duct. the maximized conditions which robot has to have are straight length of 40.152mm, inclination of $45^{\circ}$. horizontal bending of $90^{\circ}$. increasing diameter of 1.28 times, and 0.625 times decreasing diameter in branch. (3) For the case of rectangular type duct. the maximized conditions are straight length of 15.987mm. aspect ratio of 4.17:1, inclination of $18.92^{\circ}$. horizontal bending of $90^{\circ}$, and 0.65 times decreasing diameter in branch.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.4
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• pp.386-395
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• 2005

With the development of a living standard, the importance of indoor air conditioning system in all kinds of buildings and vehicles has increased. A lot of researches on energy losses in a duct and various kinds of flow pattern in branches or junctions have been carried out over many years, because the primary object of a duct system used in HVAC is to provide equal flow rate in the interior of each room by minimizing pressure drop. In this study, to get equal flow distribution in each branch, a blockage is applied to the rectangular duct system. The flow analysis for flow distribution of a rectangular duct with two branches was performed by CFD. By using SIMPLE algorithm and finite volume method, flow analysis is performed in the case of 3-D, incompressible, turbulent flow. Also, the standard $k-{\varepsilon}$ model and wall function method were used for analysis of turbulent fluid flow. The distribution diagrams of static pressure, velocity vector, turbulent energy and kinetic energy in accordance with variation of Reynolds number and blockages location in a rectangular duct show that flow distribution at duct outlets is improved by a blockage. In this rectangular duct system, mean velocity and flow rate distribution in two branch outlets are nearly constant regardless of variation of Reynolds number, and a flow pattern of the internal duct has a same tendency as well.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.9
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• pp.766-773
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• 2002

Flow distributions in a rectangular duct with two branch ducts are measured by 5 W laser doppler velocity meter. The fluid flows are also computed by commercial soft-ware of STAR-CD for comparison between them. The Reynolds numbers in the main duct are from 4,226 to 17,491. The ratios distributed into two branches from the main duct are in-variant to Reynolds numbers according to both of numerical and experimental results. However computed velocity profiles at exit of each branch are somewhat different from measured profiles at the same location.

• Journal of ILASS-Korea
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• v.1 no.3
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• pp.37-50
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• 1996

Computational fluid dynamics was used to optimize an A/C duct. Three dimensional flow analysis in an automotive A/C duct was performed computationally using various turbulence models and compared numerical predictions such as outlet flow split, surface pressure distribution along the duct to experimental data. Additionally, we studied the effect of location variation of 2nd branch on exit flow ratio and could find optimal location of 2nd branch. The design of an A/C duct was modeled and calculated to enhance the airflow distribution in each outlet using the STAR-CD computational fluid dynamics software. In results, modified $k-\varepsilon$ turbulence model allows a successful prediction of static pressure distribution particulary at around strong curvature but little improvement flow split. In the future, adoption of CFD to design an A/C duct with modified $k-\varepsilon$ model will bring benefits of producing more accurate prediction, and also give designers more detail information much more than now.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.71-74
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• 2002

Fluid flow in a rectangular duct system are measured by W laser doppler velocity meter, and also computed by commercial software of STAR-CD for comparison between then First, for a rectangular duct with 90 degree metered elbow, the fluid flow with Reynolds numbs's of 1,508 is predicted by assumption of both laminar and turbulent models. But, even though the Reynolds number is less than 2,300-3,000, the computation by turbulent model is close to the experimental data. Moeover, the computation by turbulent model for Reynolds number of 11,751 also predicts the experimental data satisfactorily. Second, for a rectangular duct with two branch ducts, the ratios between flow rates in the two branches are invariant to Reynolds number according to both of numerical and experimental results.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.376-380
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• 2009

The transmission noise characteristics through the ventilating duct was conducted numerically using SYSNOISE. A ventilating system is usually composed of mufflers for preventing noise transmission from the ventilator into indoors through the ducts and distributors for transferring air to or from each room. The transmitted noise characteristics of distributors which have different branch angles and of mufflers having different shapes were analyzed numerically. New duct element combining a muffler and a T-shaped distributor was developed for better noise reduction in this paper. New element's performance was shown numerically.

• International Journal of Air-Conditioning and Refrigeration
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• v.11 no.2
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• pp.51-60
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• 2003

In the nuclear power plant, emergency core coolant system (ECCS) is furnished at reactor coolant system (RCS) in order to cool down high temperature water in case of emergency. However, in this coolant system, thermal stratification phenomenon can occur due to coolant leaking in the check valve. The thermal stratification produces excessive thermal stresses at the pipe wall so as to yield thermal fatigue crack (TFC) accident. In the present study, effects of turbulence penetration on the thermal stratification into T-branches with square cross-section in the modeled ECCS are analysed numerically. Standard k-$\varepsilon$ model is employed to calculate the Reynolds stresses in momentum equations. Results show that the length and strength of thermal stratification are primarily affected by the leak flow rate of coolant and the Reynolds number of duct. Turbulence penetration into the T-branch of ECCS shows two counteracting effects on the thermal stratification. Heat transport by turbulence penetration from main duct to leaking flow region may enhance thermal stratification while the turbulent diffusion may weaken it.