Natural Convection from a Horizontal Heat Sink: Numerical Simulation Using Fluent 19.2

Natural Convection from a Horizontal Heat Sink: Numerical Simulation Using Fluent 19.2 PDF

Author: Hesham Khalil

Publisher: Fluent Tutorials

Published: 2019-03-02

Total Pages: 98

ISBN-13: 9781798498675

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Natural convection is a phenomenon occurs when heat is transferred to a fluid, which raises its temperature and decreases its density and consequently makes it flows upward. This book is a complete tutorial on how to simulate this kind of phenomenon using ANSYS Fluent 19.2. This is applied to a simple application of cooling a small surface using a heat sink. The tutorial starts with creating the 3D domain itself inside ANSYS DesignModeler, then discretizing it (Meshing) in ANSYS Meshing application. After that, the model is defined in Fluent with the appropriate boundary conditions. Finally, the output data is processed in Fluent to see the resulting flow around the heat sink and the temperature distribution in both the fluid and the heat sink itself.This a tutorial for the complete steps required to complete this kind of simulation. It is presented in the form of high-resolution screenshots of the applications' windows which are preceded by a textual description of the steps. Also, some of these screenshots are followed by an explanation of the different choices when seen appropriate.

CFD Calculation of Internal Natural Convection in the Annulus Between Horizontal Concentric Cylinders

CFD Calculation of Internal Natural Convection in the Annulus Between Horizontal Concentric Cylinders PDF

Author:

Publisher:

Published: 2002

Total Pages: 45

ISBN-13:

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The objective of this heat transfer and fluid flow study is to assess the ability of a computational fluid dynamics (CFD) code to reproduce the experimental results, numerical simulation results, and heat transfer correlation equations developed in the literature for natural convection heat transfer within the annulus of horizontal concentric cylinders. In the literature, a variety of heat transfer expressions have been developed to compute average equivalent thermal conductivities. However, the expressions have been primarily developed for very small inner and outer cylinder radii and gap-widths. In this comparative study, interest is primarily focused on large gap widths (on the order of half meter or greater) and large radius ratios. From the steady-state CFD analysis it is found that the concentric cylinder models for the larger geometries compare favorably to the results of the Kuehn and Goldstein correlations in the Rayleigh number range of about 105 to 108 (a range that encompasses the laminar to turbulent transition). For Rayleigh numbers greater than 108, both numerical simulations and experimental data (from the literature) are consistent and result in slightly lower equivalent thermal conductivities than those obtained from the Kuehn and Goldstein correlations.

Numerical Simulation of Natural Convection in Rectangular Enclosures of Varying Aspect Ratios and Its Feasibility in Environmental Impact Management Studies

Numerical Simulation of Natural Convection in Rectangular Enclosures of Varying Aspect Ratios and Its Feasibility in Environmental Impact Management Studies PDF

Author: Charles Randall Walker

Publisher:

Published: 2012

Total Pages: 150

ISBN-13:

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Author's abstract: Numerical simulation was used to investigate natural convection in horizontal and vertical enclosures with and without an internal heat source. Natural convection in rectangular enclosures is found in many real-world applications. Included in these applications are the energy efficient design of buildings, operation and safety of nuclear reactors, solar collector design, passive energy storage, heat transfer across multi-pane windows, thermo-electric refrigeration and heating devices, and the design-for-mitigation of optical distortion in large- scale laser systems. Considering all these applications, especially controlling heat transfer in nuclear power plants, knowledge and research results of natural convection in enclosure play a vital role in environmental impact management studies. This study simulated horizontal enclosures heated from below (configuration 1) and vertical enclosures heated from the side (configuration 2) with a variety of different aspect ratios (AR) and Rayleigh numbers (Ra). Each aspect ratio (1, 2, 4, 6, 8, and 10) was examined using different sets of Rayleigh numbers. The first numerical experiment used only external Rayleigh number (RaE = 2×104, 2×105, and 2×106) which simulated natural convection in enclosures for outside temperature gradient only. The second case used a constant external Rayleigh number (RaE = 2×105) with a changing internal Rayleigh number (RaI = 2×104, 2×105, and 2×106). The third simulation used a constant internal Rayleigh number (Ra I = 2×105) and a changing external Raleigh number (RaE = 2×104, 2×105, and 2×106). All three cases were simulated for each configuration and at each aspect ratio. The streamline and isotherm flow patterns were created to reflect each case. The average heat flux ratio and convection strength were also calculated. Tests with the external temperature gradient only confirmed previous studies. There were many notable outcomes in this study which are discussed in the main body of this thesis work. When RaE> RaI, the results were similar to the study with a varying external Rayleigh number (RaE) and no internal heat source.

Numerical Simulation of Natural Convection in Ventilated Façades

Numerical Simulation of Natural Convection in Ventilated Façades PDF

Author: Milad Najafzadeh Babaei

Publisher:

Published: 2014

Total Pages:

ISBN-13:

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Numerical simulation on the influence of surface convection on the laminar air flow induced by natural convection in vertical parallel plates is explained. This simulation discussed symmetrically and asymmetrically for uniform heated flux (UHF) and uniform wall temperature (UWT) cases. The effects of variable fluid parameters taken into account for incompressible Navier-Stokes equations. The thermophysical properties variation are determined from air temperature at the inlet of channel. Distribution of several parameters in different sections considered and visited for natural convection. Many tests in various conditions have been undertaken for incompressible Navier-Stokes equations to allow evaluating average Nusselt numbers and air mass flow rate in this thesis. It has found out narrow vertical channels with different aspect ratios exhibit different heat transfer behaviours. Influence of mesh refinement on physical characteristic behaviour has been investigated. Several specific numerical codes, based on stabilized finite element method (FEM) used to solve the incompressible Navier-Stokes equations within the air gap region. These specific codes are suitable to determine the accuracy of heat transfer behaviours in different areas.

Verification of a Numerical Simulation Technique for Natural Convection

Verification of a Numerical Simulation Technique for Natural Convection PDF

Author: A. Gadgil

Publisher:

Published: 1983

Total Pages: 16

ISBN-13:

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The present paper describes a verification of CONVEC2 for single-zone geometries by comparison with the results of two natural convection experiments performed in small-scale rectangular enclosures. These experiments were selected because of the high Rayleigh numbers obtained and the small heat loss through the insulated surfaces. Comparisons are presented for (1) heat transfer rates, (2) fluid temperature profiles, and (3) surface heat flux distributions.

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