A new wall boundary condition for the standard Wilcox’s k–ω model (1988) is proposed. The model combines a wall function and a low-Reynolds number approach, and a function that smoothly blends the two formulations, enabling the model to be used independently of the location of the first interior computational node. The model is calibrated using DNS-data for a channel flow and applied to a heat transfer prediction for a flow in a rib-roughened channel (Reb = 100 000). The results obtained with the new model are improved for various mesh sizes and are asymptotically identical with those of the standard k–ω turbulence model.
{"title":"On the Wall Boundary Condition for Computing Turbulent Heat Transfer With K–ω Models","authors":"J. Bredberg, S. Peng, L. Davidson","doi":"10.1115/imece2000-1582","DOIUrl":"https://doi.org/10.1115/imece2000-1582","url":null,"abstract":"\u0000 A new wall boundary condition for the standard Wilcox’s k–ω model (1988) is proposed. The model combines a wall function and a low-Reynolds number approach, and a function that smoothly blends the two formulations, enabling the model to be used independently of the location of the first interior computational node. The model is calibrated using DNS-data for a channel flow and applied to a heat transfer prediction for a flow in a rib-roughened channel (Reb = 100 000). The results obtained with the new model are improved for various mesh sizes and are asymptotically identical with those of the standard k–ω turbulence model.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134004522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Deng, M. Gordon, L. Roe, A. Malshe, W. F. Schmidt
In an effort to better understand and thereby utilize laser processing, an existing code describing laser-metal (aluminum) interaction is modified to describe laser-ceramic (diamond) interaction. Comparisons between our modified code (diamond target) and the original code (aluminum target) highlight similarities and differences between laser-ceramic and laser-metal processing. Gas breakdown effects, which are expected for the simulated short (time duration), high energy laser pulses, are observed in both codes. Due to the lower sublimation heat of aluminum (1.1×104J/g) compared to diamond (5.3×104J/g), aluminum vaporizes more quickly and exhibits a faster expansion speed (1.4×107 cm/sec compared to 8×106 cm/sec for diamond) in the early stage of the laser pulse. Because aluminum requires significantly more energy to fully ionize than does carbon, our simulations show that the diamond plasma is fully ionized (6 of 6 electrons per atom) and the aluminum plasma is partially ionized (11 of 13 electrons per atom).
{"title":"Comparison of Laser-Ceramic and Laser-Metal Material Processing","authors":"G. Deng, M. Gordon, L. Roe, A. Malshe, W. F. Schmidt","doi":"10.1115/imece2000-1553","DOIUrl":"https://doi.org/10.1115/imece2000-1553","url":null,"abstract":"\u0000 In an effort to better understand and thereby utilize laser processing, an existing code describing laser-metal (aluminum) interaction is modified to describe laser-ceramic (diamond) interaction. Comparisons between our modified code (diamond target) and the original code (aluminum target) highlight similarities and differences between laser-ceramic and laser-metal processing. Gas breakdown effects, which are expected for the simulated short (time duration), high energy laser pulses, are observed in both codes. Due to the lower sublimation heat of aluminum (1.1×104J/g) compared to diamond (5.3×104J/g), aluminum vaporizes more quickly and exhibits a faster expansion speed (1.4×107 cm/sec compared to 8×106 cm/sec for diamond) in the early stage of the laser pulse. Because aluminum requires significantly more energy to fully ionize than does carbon, our simulations show that the diamond plasma is fully ionized (6 of 6 electrons per atom) and the aluminum plasma is partially ionized (11 of 13 electrons per atom).","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"173 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127302841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A simplified finite element model is built to study the thermal response of the 193-nm pulsed-laser calorimeter. The nonequivalence between pulsed-laser heating and electrical heating is estimated to be 0.46% at the thermocouple locations by comparing the calibration factors for average-power laser heating and electrical heating. This study should help the development of calibration and measurement standards in pulsed energy measurements for deep ultraviolet excimer lasers that are important for photolithographic and materials processing applications.
{"title":"Thermal Modeling of the Cavity in Pulsed Excimer Laser Calorimeters","authors":"D. Chen, Z. M. Zhang","doi":"10.1115/imece2000-1574","DOIUrl":"https://doi.org/10.1115/imece2000-1574","url":null,"abstract":"\u0000 A simplified finite element model is built to study the thermal response of the 193-nm pulsed-laser calorimeter. The nonequivalence between pulsed-laser heating and electrical heating is estimated to be 0.46% at the thermocouple locations by comparing the calibration factors for average-power laser heating and electrical heating. This study should help the development of calibration and measurement standards in pulsed energy measurements for deep ultraviolet excimer lasers that are important for photolithographic and materials processing applications.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125438125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The velocity distributions inside a centrifugal separator with outside and inside diameters of 152.4 mm (6″) and 76.2 mm (3″), respectively, have been investigated experimentally and numerically to obtain optimum separation efficiency. Two 12.7 mm (1/2-inch) holes were drilled on the external surface of the separator to measure the velocity distribution in the separator. Two direction velocities (tangential direction along the cylinder surface and axial along the vertical direction) were measured to compare with the numerical simulation results. A 6060P Pitot probe was employed to obtain the velocity distribution. The dust samples (a mixture of steel particle and dust) from the dust collection box were analyzed using a Phillips XL30 Scanning Electron Microscope. FLUENT code is used as the numerical solver for this fully three-dimensional problem. The fluid flow in the separator is assumed to be steady and incompressible turbulent flow. The standard k–ε model was employed in this study. Non-uniform, unstructured grids are chosen to discretize the entire computation domain. Almost 100,000 cells are used to discretize the whole separator. The constant velocity profile is imposed on the inlet plane. The pressure boundary condition is adopted at outlet plane. Comparing the velocity distribution and separation efficiency from the experiment and the numerical modeling shows that the experimental results and the estimated data agree fairly well and with a deviation within ±10%.
{"title":"Experimental and Numerical Investigation of Air-Particle Two-Phase Flow in Centrifugal Separator","authors":"H. Kang, B. Zheng, C. Lin, M. Ebadian","doi":"10.1115/imece2000-1578","DOIUrl":"https://doi.org/10.1115/imece2000-1578","url":null,"abstract":"\u0000 The velocity distributions inside a centrifugal separator with outside and inside diameters of 152.4 mm (6″) and 76.2 mm (3″), respectively, have been investigated experimentally and numerically to obtain optimum separation efficiency. Two 12.7 mm (1/2-inch) holes were drilled on the external surface of the separator to measure the velocity distribution in the separator. Two direction velocities (tangential direction along the cylinder surface and axial along the vertical direction) were measured to compare with the numerical simulation results. A 6060P Pitot probe was employed to obtain the velocity distribution. The dust samples (a mixture of steel particle and dust) from the dust collection box were analyzed using a Phillips XL30 Scanning Electron Microscope.\u0000 FLUENT code is used as the numerical solver for this fully three-dimensional problem. The fluid flow in the separator is assumed to be steady and incompressible turbulent flow. The standard k–ε model was employed in this study. Non-uniform, unstructured grids are chosen to discretize the entire computation domain. Almost 100,000 cells are used to discretize the whole separator. The constant velocity profile is imposed on the inlet plane. The pressure boundary condition is adopted at outlet plane. Comparing the velocity distribution and separation efficiency from the experiment and the numerical modeling shows that the experimental results and the estimated data agree fairly well and with a deviation within ±10%.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128003747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Numerical modeling was performed to investigate the buoyancy effect on developing turbulent flow and the heat transfer characteristics of saturated water in a helical pipe with finite pitch. The renormalization group (RNG) κ–ε model was used to account for the turbulent flow and heat transfer in the helical pipe at a constant wall temperature with or without buoyancy force effect. A control volume method with second-order accuracy was used to numerically solve the three-dimensional full elliptic governing equations for this problem. The O-type nonuniform structured grid system was adopted to discretize the computation domain. The Boussinesq approximation was applied to deal with the buoyancy. This study explored the influence of buoyancy on the developing heat transfer along the helical pipe. Based on the results of this research, the velocity, temperature, and Nusselt number are presented graphically and analyzed.
{"title":"Buoyancy Effect on Developing Turbulent Flow and Heat Transfer in a Helical Pipe With Finite Pitch","authors":"B. Zheng, C. Lin, M. Ebadian","doi":"10.1115/imece2000-1581","DOIUrl":"https://doi.org/10.1115/imece2000-1581","url":null,"abstract":"\u0000 Numerical modeling was performed to investigate the buoyancy effect on developing turbulent flow and the heat transfer characteristics of saturated water in a helical pipe with finite pitch. The renormalization group (RNG) κ–ε model was used to account for the turbulent flow and heat transfer in the helical pipe at a constant wall temperature with or without buoyancy force effect. A control volume method with second-order accuracy was used to numerically solve the three-dimensional full elliptic governing equations for this problem. The O-type nonuniform structured grid system was adopted to discretize the computation domain. The Boussinesq approximation was applied to deal with the buoyancy. This study explored the influence of buoyancy on the developing heat transfer along the helical pipe. Based on the results of this research, the velocity, temperature, and Nusselt number are presented graphically and analyzed.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121784028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yongmao Zhou, Y. J. Shen, Zhuomin M. Zhang, B. Tsai, D. Dewitt
This work employs a Monte Carlo method to study the radiative process in a rapid thermal processing (RTP) furnace. A “true” effective emissivity, accounting for the directional optical properties, is defined and predicted in order to determine the wafer temperature from the measured spectral radiance temperature using light-pipe radiation thermometry. The true effective emissivity is the same as the hemispherical effective emissivity for diffuse wafers, in which case the Monte Carlo model gives the same results as the net-radiation method. Deviations exist between the hemispherical effective emissivity and the true effective emissivity for specular wafers because the effective emissivity is directional dependent. This research will help reduce the uncertainty in the temperature measurement for RTP furnaces to meet the future requirements for integrated circuit manufacturing.
{"title":"Monte Carlo Simulation for Radiometric Temperature Measurement in Rapid Thermal Processing","authors":"Yongmao Zhou, Y. J. Shen, Zhuomin M. Zhang, B. Tsai, D. Dewitt","doi":"10.1115/imece2000-1575","DOIUrl":"https://doi.org/10.1115/imece2000-1575","url":null,"abstract":"\u0000 This work employs a Monte Carlo method to study the radiative process in a rapid thermal processing (RTP) furnace. A “true” effective emissivity, accounting for the directional optical properties, is defined and predicted in order to determine the wafer temperature from the measured spectral radiance temperature using light-pipe radiation thermometry. The true effective emissivity is the same as the hemispherical effective emissivity for diffuse wafers, in which case the Monte Carlo model gives the same results as the net-radiation method. Deviations exist between the hemispherical effective emissivity and the true effective emissivity for specular wafers because the effective emissivity is directional dependent. This research will help reduce the uncertainty in the temperature measurement for RTP furnaces to meet the future requirements for integrated circuit manufacturing.","PeriodicalId":221080,"journal":{"name":"Heat Transfer: Volume 5","volume":"43 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113943901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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