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Phan, Thanh-Hoang,Ha, Cong-Tu,Park, Warn-Gyu Elsevier 2018 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.127 No.1
<P><B>Abstract</B></P> <P>The present study aims at validating a computer simulation code for compressible interface flows with and without mass transfers. The numerical method was based on a dual-time fully compressible multiphase homogeneous mixture flow model. The interfaces with a large jump in density, pressure, velocity, and temperature were captured using a compressive high-resolution interface-capturing scheme. Lee’s boiling model was adopted for implementing the mass and energy transfers via interfaces. The bubble collapse between two parallel walls was first examined. The bubble profile during the collapse process was predicted and compared with experimental images. The numerical results showed good agreement. To evaluate the present model for multiphase flows, including the effects of heat and mass transfers, computations were performed for saturated film boiling on a sphere at atmospheric pressure. The evolution of the wavy liquid–vapor interface around the sphere during the film boiling process was observed. The time-averaged heat fluxes obtained from the numerical simulation were compared with those predicted from numerical data and analytical correlations. The effects of the superheated wall on heat fluxes were also investigated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The validation of a computer simulation code for multiphase flows is implemented. </LI> <LI> A fully compressible two-phase homogeneous mixture flow model is presented. </LI> <LI> Bubble collapse between two parallel walls and saturated film boiling on a sphere are examined. </LI> <LI> The predicted time-averaged heat fluxes agree well with those in previous studies. </LI> </UL> </P>
Hoang Nguyen(Hoang Nguyen ),Tu Phan Thanh(Tu Phan Thanh ),Hee-Cheol Moon(Hee-Cheol Moon),Binh Do(Binh Do ) The International Academy of Global Business and T 2023 The International Academy of Global Business and T Vol.19 No.3
Purpose - Given the significance of concerns raised about the global shift toward protectionism under trade policy uncertainty context, and echoed by requests to contribute to issues that concern a wider variety of stakeholders, this study aims to review new trade protection measures in response to the pandemic crisis and their effects on export performance from an emerging country’s exporters. Design/Methodology/Approach - Research data were gathered by surveying 613 export managers of different types of exporters in Vietnam from a list of exporters provided by Ministry of Industry and Trade, and then applied a regression model for analysis. Findings - The study demonstrated a negative relationship between firm export performance and six trade protectionism measures, including industrial subsidies, public-procurement restrictions, FDI restrictions, standards protectionism, green protectionism, and regional integration. Only restrictions on migrant workers had no appreciable impact on firm export performance. Additionally, only employee number, out of the three control factors, significantly and positively affected how well firms succeed in exporting. Research Implications - The study’s findings have significant ramifications and contributions to theory and practice in international trade for an emerging country to overcome new trade protectionism measures. To support firms in expanding export markets, the government of an emerging country should concentrate on establishing and developing policies to support exporters, especially small and medium enterprises. Firms should pursue a sustainable export strategy in light of the emergence of new trade protectionism in significant import markets.
Thanh-Hoang Phan,Van-Tu Nguyen,Duy-Trong Nguyen,Dong-Hyun Kim,Warn-Gyu Park 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
In this study, we aimed to explore the phase-change mechanisms and their effects on the cavitation bubble dynamics in a free-field condition over multiple cycles. A combination of a two-phase homogeneous mixture model and interface-capturing method was adopted to simulate the bubble dynamics. Complex phase-change mechanisms were evaluated to explore the major influence phenomenon on the bubble dynamics. By comparing with experimental data, a compatible bubble radius evolution under a free-field condition was obtained, particularly at the rebound and collapse stages. Disturbance secondary cavitation regions in the water field induced by rarefaction waves were observed immediately after the second rebound stage. In addition, bubble dynamic behaviors were mainly affected by the condensation mechanism. We found that the condensation phenomenon mainly occurs at the vapor–water bubble interfaces with a thin boundary layer.