The current study reports a numerical analysis of free convection of air in an isothermal horizontal cylinder,cooled and heated at different wall locations.Three heater sizes are discussed in this study.The first heat...The current study reports a numerical analysis of free convection of air in an isothermal horizontal cylinder,cooled and heated at different wall locations.Three heater sizes are discussed in this study.The first heated zone is spread across one-quarter of the sidewall;the second is uniformly distributed over the half of the wall and the third active wall covers three-quarters of the cylinder.Five various locations are considered and examined for each active zone of the sidewall.The computation is carried out for Rayleigh number ranging from 102 to 106.Numerical results characterizing heat transfer and flow features are achieved using an iterative model developed in COMSOL Multiphysics.The effect of Rayleigh number on heat transfer and fluid flow characteristics within the cavity are investigated.Particular attention is paid to the influence of heater location and heater size on energy efficiency.It is found that the mean Nusselt number and dimensionless velocity increase when increasing the Rayleigh number.Moreover,the optimal level of energy efficiency is achieved if the heating zone is centered at the upper part of the cylinder,regardless of the heater size.It is also shown that the optimal configuration providing higher energy efficiency is obtained when three-quarters of the sidewall are locally heated,and more precisely,if the active zone is centered at the top of the cylinder.展开更多
There are at least two valid approaches to the thermodynamics of electrons in metals. One takes a microscopic view, based on models of electrons in metals and superconductor and uses statistical mechanics to calculate...There are at least two valid approaches to the thermodynamics of electrons in metals. One takes a microscopic view, based on models of electrons in metals and superconductor and uses statistical mechanics to calculate the total thermodynamic functions for the model-based system. Another uses partial molar quantities, which is a rigorous thermodynamic method to analyze systems with components that can cross phase boundaries and is particularly useful when applied to a system composed of interacting components. Partial molar quantities have not been widely used in the field of solid state physics. The present paper will explore the application of partial molar electronic entropy and partial molar electronic heat capacity to electrons in metals and superconductors. This provides information that is complementary information from other approaches to the thermodynamics of electrons in metals and superconductors and can provide additional insight into the properties of those materials. Furthermore, the application of partial molar quantities to electrons in metals and superconductors has direct relevance to long-standing problems in other fields, such as the thermodynamics of ions in solution and the thermodynamics of biological energy transformations. A unifying principle between reversible and irreversible thermodynamics is also discussed, including how this relates to the completeness of thermodynamic theory.展开更多
A numerical study based on the finite volume method has been performed to study the three-dimension natural convection in a parallelogrammic top side opened cavity filled nanofluid with partially heated square at the ...A numerical study based on the finite volume method has been performed to study the three-dimension natural convection in a parallelogrammic top side opened cavity filled nanofluid with partially heated square at the bottom side.Results are obtained for different governing parameters such as nanoparticle concentration (φ) from 0 to 0.05,inclination angle of the back and front walls (α) from 5° to 75°,Rayleigh number from 10^3 to 10^5,and length of heater changer from 0.1 to 1.The main finding from the obtained result showed that the inclination angle and nanoparticle volume fraction affect the flow structure and enhance the heat transfer.展开更多
This article attempts to give a short survey of recent progress on a class of elementary stochastic partial differential equations (for example, stochastic heat equations) driven by Gaussian noise of various covarianc...This article attempts to give a short survey of recent progress on a class of elementary stochastic partial differential equations (for example, stochastic heat equations) driven by Gaussian noise of various covariance structures. The focus is on the existence and uniqueness of the classical (square integrable) solution (mild solution, weak solution). It is also concerned with the Feynman-Kac formula for the solution;Feynman-Kac formula for the moments of the solution;and their applications to the asymptotic moment bounds of the solution. It also briefly touches the exact asymptotics of the moments of the solution.展开更多
Laminar natural convection heat transfer inside air-filled, rectangular enclosures partially heated from below and cooled at one side is studied numerically. A computational code based on the SIMPLE-C algorithm is use...Laminar natural convection heat transfer inside air-filled, rectangular enclosures partially heated from below and cooled at one side is studied numerically. A computational code based on the SIMPLE-C algorithm is used for the solution of the system of the mass, momentum, and energy transfer governing equations. Simulations are performed for a complete range of heater size, for Rayleigh numbers based on the height of the cavity ranging from 10~3to 10~6, and for height-to-width aspect ratios of the cavity spanning from 0.25 to 4. It is found that the heat transfer rate increases with increasing the heater size and the Rayleigh number, while it decreases with increasing the aspect ratio of the cavity. Dimensionless heat transfer correlations are also proposed.展开更多
文摘The current study reports a numerical analysis of free convection of air in an isothermal horizontal cylinder,cooled and heated at different wall locations.Three heater sizes are discussed in this study.The first heated zone is spread across one-quarter of the sidewall;the second is uniformly distributed over the half of the wall and the third active wall covers three-quarters of the cylinder.Five various locations are considered and examined for each active zone of the sidewall.The computation is carried out for Rayleigh number ranging from 102 to 106.Numerical results characterizing heat transfer and flow features are achieved using an iterative model developed in COMSOL Multiphysics.The effect of Rayleigh number on heat transfer and fluid flow characteristics within the cavity are investigated.Particular attention is paid to the influence of heater location and heater size on energy efficiency.It is found that the mean Nusselt number and dimensionless velocity increase when increasing the Rayleigh number.Moreover,the optimal level of energy efficiency is achieved if the heating zone is centered at the upper part of the cylinder,regardless of the heater size.It is also shown that the optimal configuration providing higher energy efficiency is obtained when three-quarters of the sidewall are locally heated,and more precisely,if the active zone is centered at the top of the cylinder.
文摘There are at least two valid approaches to the thermodynamics of electrons in metals. One takes a microscopic view, based on models of electrons in metals and superconductor and uses statistical mechanics to calculate the total thermodynamic functions for the model-based system. Another uses partial molar quantities, which is a rigorous thermodynamic method to analyze systems with components that can cross phase boundaries and is particularly useful when applied to a system composed of interacting components. Partial molar quantities have not been widely used in the field of solid state physics. The present paper will explore the application of partial molar electronic entropy and partial molar electronic heat capacity to electrons in metals and superconductors. This provides information that is complementary information from other approaches to the thermodynamics of electrons in metals and superconductors and can provide additional insight into the properties of those materials. Furthermore, the application of partial molar quantities to electrons in metals and superconductors has direct relevance to long-standing problems in other fields, such as the thermodynamics of ions in solution and the thermodynamics of biological energy transformations. A unifying principle between reversible and irreversible thermodynamics is also discussed, including how this relates to the completeness of thermodynamic theory.
文摘A numerical study based on the finite volume method has been performed to study the three-dimension natural convection in a parallelogrammic top side opened cavity filled nanofluid with partially heated square at the bottom side.Results are obtained for different governing parameters such as nanoparticle concentration (φ) from 0 to 0.05,inclination angle of the back and front walls (α) from 5° to 75°,Rayleigh number from 10^3 to 10^5,and length of heater changer from 0.1 to 1.The main finding from the obtained result showed that the inclination angle and nanoparticle volume fraction affect the flow structure and enhance the heat transfer.
基金supported by an NSERC granta startup fund of University of Alberta
文摘This article attempts to give a short survey of recent progress on a class of elementary stochastic partial differential equations (for example, stochastic heat equations) driven by Gaussian noise of various covariance structures. The focus is on the existence and uniqueness of the classical (square integrable) solution (mild solution, weak solution). It is also concerned with the Feynman-Kac formula for the solution;Feynman-Kac formula for the moments of the solution;and their applications to the asymptotic moment bounds of the solution. It also briefly touches the exact asymptotics of the moments of the solution.
文摘Laminar natural convection heat transfer inside air-filled, rectangular enclosures partially heated from below and cooled at one side is studied numerically. A computational code based on the SIMPLE-C algorithm is used for the solution of the system of the mass, momentum, and energy transfer governing equations. Simulations are performed for a complete range of heater size, for Rayleigh numbers based on the height of the cavity ranging from 10~3to 10~6, and for height-to-width aspect ratios of the cavity spanning from 0.25 to 4. It is found that the heat transfer rate increases with increasing the heater size and the Rayleigh number, while it decreases with increasing the aspect ratio of the cavity. Dimensionless heat transfer correlations are also proposed.
