نتایج جستجو برای: rayleigh numbers

تعداد نتایج: 210800  

A. Aghaei G.A. Sheikhzadeh H.R. Ehteram M. Hajiahmadi

Natural convection heat transfer has many applications in different fields of industry; such as cooling industries, electronic transformer devices and ventilation equipment; due to simple process, economic advantage, low noise and renewed retrieval. Recently, heat transfer of nanofluids have been considered because of higher thermal conductivity coefficient compared with those of ordinary fluid...

2008
Tanmay Basak S. Roy Krishna Babu

A penalty finite element analysis with bi-quadratic elements is carried out to investigate the effects of uniform and non-uniform heating of inclined walls on natural convection flows within a isosceles triangular enclosure. Two cases of thermal boundary conditions are considered; case I: two inclined walls are uniformly heated while the bottom wall is cold isothermal and case II: two inclined ...

A steady two-dimensional laminar free convection heat transfer from a cold horizontal isothermal cylinder located above an adiabatic floor is studied both experimentally and numerically. In the experimental measurements the effects of cylinder distance from horizontal floor to its diameter (L/D) on heat transfer coefficient is studied for Rayleigh numbers of 3×105 and 6×105. Computations are ma...

In this work, analysis of heat transfer in porous fin with temperature-dependent thermal conductivity and internal heat generation is carried out using Chebychev spectral collocation method. The numerical solutions are used to investigate the influence of various parameters on the thermal performance of the porous fin. The results show that increase in convective parameter, porosity parameter, ...

E. Fattahi K. Sedighi M. Farhadi

This work presents a numerical analysis of entropy generation in Γ-Shaped enclosure that was submitted to the natural convection process using a simple thermal lattice Boltzmann method (TLBM) with the Boussinesq approximation.  A 2D thermal lattice Boltzmann method with 9 velocities, D2Q9, is used to solve the thermal flow problem. The simulations are performed at a constant Prandtl number (Pr ...

2000
C. BECKERMANN

A Rayleigh number based criterion is developed for predicting the formation of freckles in Ni-base superalloy castings. This criterion relies on finding the maximum local Rayleigh number in the mush, where the ratio of the driving buoyancy force to the retarding frictional force is the largest. A critical Rayleigh number for freckle formation of approximately 0.25 is found from available experi...

Journal: :Physics of Fluids 2021

In this paper, we extend Grossmann and Lohse’s (GL) model [S. D. Lohse, “Thermal convection for large Prandtl numbers,” Phys. Rev. Lett. 86, 3316 (2001)] the predictions of Reynolds number (Re) Nusselt (Nu) in turbulent Rayleigh–Bénard convection. Toward objective, use functional forms prefactors dissipation rates bulk boundary layers. The arise due to inhibition nonlinear interactions presence...

حاج زمان, رضا, رحمتی, احمدرضا,

In this study, for the first time natural convection heat transfer of Al2O3-water nanofluid with constant and variable properties is investigated within square shape porous media using the lattice Boltzmann method. The horizontal walls of the cavity are insulated, and left and right vertical walls are hot and cold, respectively. The Study have been carried out for Rayleigh numbers of 103, 10...

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