| 1. |
- Asako, Y., et al.
(författare)
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Mach Number on Outlet Plane of a Straight Micro-Tube
- 2014
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Ingår i: Proceedings of the ASME 2013 International Mechanical Engineering Congress and Exposition. Volume 7A: Fluids Engineering Systems and Technologies. - 9780791856314 ; 7A, s. 07-020
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Konferensbidrag (refereegranskat)abstract
- The Mach number and pressure on the outlet plane of a straight micro-tube were investigated numerically for both laminar and turbulent flow cases. The numerical methodology is based on the Arbitrary-Lagrangian-Eulerian (ALE) method. The LB1 turbulence model was used for the turbulent flow case. The compressible momentum and energy equations with the assumption of the ideal gas were solved. The computational domain is extended to the downstream region from the micro-tube outlet. The back pressure was given to the outside of the downstream region. The computations were performed for a tube whose diameter ranges from 50 to 500 gm. The average Mach number on the outlet plane of the fully under-expanded flow depends on the tube diameter and ranges from 1.16 to 1.25. The flow characteristics of the under-expanded gas flow in a straight micro-tube were revealed.
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| 2. |
- Yamada, Toru, et al.
(författare)
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Diffusive-Ballistic Heat Transport in a Two-Dimensional Square Plate Using Energy Conserving Dissipative Particle Dynamics
- 2014
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Ingår i: ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology Volume 4: Heat and Mass Transfer Under Extreme Conditions. - 9780791855508 ; 4, s. 004-016
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Konferensbidrag (refereegranskat)abstract
- Diffusive-ballistic heat transport in a two-dimensional square plate was simulated using energy conserving dissipative particle dynamics (DPDe). The solution domain was considered to be a two-dimensional square plate surrounded by walls at constant temperatures, where DPD particles are uniformly distributed. The effects of phonon mean free path was incorporated by its relation to the cutoff radius of energy interaction. This cutoff radius was obtained based on Knudsen number (Kn) using the existing phonon-boundary scattering models. The simulations for 0.1 < Kn < 10 were conducted with different modifications of the cutoff radius. The results are presented in form of temperature distributions in the solution domain and the effect of Knudsen number is discussed.
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| 3. |
- Yamada, Toru, et al.
(författare)
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Diffusive-ballistic heat transport in thin films using energy conserving dissipative particle dynamics
- 2013
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310. ; 61, s. 287-292
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Tidskriftsartikel (refereegranskat)abstract
- Diffusive-ballistic heat transport in thin films was simulated using energy conserving dissipative particle dynamics (DPDe). The solution domain was considered to be two-dimensional with DPD particles distributed uniformly under constant temperature boundary conditions at the top and bottom walls and periodic boundaries at the side walls. The effects of phonon mean free path were incorporated by its relation to the cutoff radius of energy interaction. This cutoff radius was based on the Knudsen number using the existing phonon-boundary scattering models. The simulations for 0.1 < Kn < 10 were obtained with the different modifications of the cutoff radius. The results were presented in form of a nondimensional temperature profile across the thin film and were compared with the semi-analytical solution of the equation of phonon radiative transport (EPRT). When the phonon-boundary scattering is not considered, the DPDe simulation results have more discrepancies compared with the EPRT solution as Kn increases, indicating that the phonon-boundary scattering plays an important role when the heat transport across the film becomes more ballistic. The results demonstrate that the DPDe can simulate the diffusive-ballistic heat transport for a broad range of Kn, but phonon-boundary scattering should be considered for the accurate simulation of the ballistic heat transport. (C) 2013 Elsevier Ltd. All rights reserved.
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| 4. |
- Yamada, Toru, et al.
(författare)
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Numerical Study on the Diffusive-Ballistic Heat Transport in a Two-Dimensional Square Plate
- 2014
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Ingår i: ASME 2013 International Mechanical Engineering Congress and Exposition Volume 8C: Heat Transfer and Thermal Engineering. - 9780791856369 ; 8C, s. 08-015
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Konferensbidrag (refereegranskat)abstract
- The heat conduction in a two-dimensional square plate at nano/micro scales is investigated using numerical and semi-analytical methodologies which are energy conserving dissipative particle dynamics (DPDe) and Boltzmann transport equation (BTE) with the gray relaxation time approximation. The solution domain was considered to be a two-dimensional square plate surrounded by walls having constant temperatures. The numerical and semi-analytical results for different Knudsen numbers ranging from 0.1 to 10 are presented in form of temperature distributions in the solution domain. These results are compared with each other and the applicability of the DPDe model to two-dimensional structures is discussed.
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| 5. |
- Yoshimaru, Takahiro, et al.
(författare)
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Under-Expanded Gaseous Flow at a Straight Micro-Tube Exit
- 2014
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Ingår i: Journal of Fluids Engineering. - : ASME International. - 0098-2202 .- 1528-901X. ; 136:8
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Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on under-expanded gaseous flow at a straight micro-tube exit. The pitot total pressure of gas flow (jet) in the downstream region from a straight micro-tube exit was measured by a total pressure pitot tube to accumulate data for validation of numerical results. A micro-tube of 495 mu m in diameter and 56.3 mm in length and a total pressure pitot tube of 100 mu m in outer diameter were used. The pitot total pressure was measured at intervals of 0.1 mm in both the flow and radial directions. The measurement was done for the mass flow rates of 9.71 x 10(-5) kg/s and 1.46 x 10(-4) kg/s. The data were accumulated for validation of the numerical results to reveal the characteristics of the under-expanded gas flow at the exit of a micro-tube. Comparisons were conducted for numerical results of corresponding cases and a slight discrepancy can be seen between numerical and experimentally measured pitot total pressures.
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