Constructal Design of a Triangular Fin Inserted in a Cavity with Mixed Convection Lid-Driven Flow

2017 ◽  
Vol 372 ◽  
pp. 188-201 ◽  
Author(s):  
Andre L. Razera ◽  
Tadeu M. Fagundes ◽  
Flávio M. Seibt ◽  
Roberta J.C. da Fonseca ◽  
Dolir J.C. Varela ◽  
...  
Keyword(s):  
Mixed Convection ◽  
Thermal Performance ◽  
Convective Heat Transfer Coefficient ◽  
Reynolds Numbers ◽  
Area Ratio ◽  
Convection Flow ◽  
Constructal Design ◽  
Cavity System ◽  
Triangular Fin ◽  
Volume Method

The present work applies Constructal Design to study numerically a fin-cavity system under mixed convection flow. The system is composed of a heat triangular fin inserted in a squared cavity. The flow is driven by the superior wall (lid) displacement. The main purpose is to study the effect of the fin geometry and area ratio (φ) over the dimensionless convective heat transfer coefficient (Nusselt number). The effect of Rayleigh (RaH) and Reynolds (ReH) numbers over the thermal performance and optimal geometries is also evaluated. For all cases the Prandtl number is constant (Pr = 0.71). The conservation equations of mass, momentum and energy are solved numerically with a code based in the Finite Volume Method (FVM). Results showed that the thermal performance increased with the increase of Reynolds and Rayleigh numbers and with the decrease of fin area ratio (φ). Otimal geometries for the triangular fin are compared to optimal rectangular fins, for RaH = 105 results showed a better performance (up to 8%) of the triangular fin for low Reynolds numbers (ReH < 200), while rectangular fins performed better than triangular ones for the highest magnitudes of ReH numbers. In general, results showed that different conditions change the optimal shape of a flow system, always evolving to architectures that facilitate the access to the flows that flow through it.

scholarly journals GEOMETRICAL EVALUATION OF RECTANGULAR FIN MOUNTED IN LATERAL SURFACE OF LID-DRIVEN CAVITY FORCED CONVECTIVE FLOWS

2019 ◽  
Vol 18 (2) ◽  
pp. 98
Author(s):  
E. D. dos Santos ◽  
P. M. Rodrigues ◽  
L. A. Isoldi ◽  
J. F. Prolo Filho ◽  
L. A. O. Rocha ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Thermal Performance ◽  
Degrees Of Freedom ◽  
Reynolds Numbers ◽  
Cavity Surface ◽  
Square Cavity ◽  
Driven Cavity ◽  
Convective Flows ◽  
Constructal Design ◽  
Volume Method

In this work, it is investigated the geometric effect of rectangular fin inserted in a lid-driven square cavity over thermal performance of laminar, incompressible, steady and forced convective flows. This study is performed by applying Constructal Design to maximize the heat transfer between the fin and the cavity flow. For that, the problem is subjected to two constraints: area of the cavity and area of rectangular fin, and two degrees of freedom: height/length ratio of rectangular fin (H1/L1) and its position in upstream surface of the cavity (S/A1/2). It is considered here some fixed parameters, as the ratio between the fin and cavity areas (ϕ = 0.05), the aspect ratio of the cavity dimensions (H/L = 1.0) and Prandtl number (Pr = 0.71). The fin aspect ratio (H1/L1) was varied for three different placements of the fin at the upstream cavity surface (S/A1/2 = 0.1, 0.5 and 0.9) which represents a lower, intermediate and upper positions of the fin. The effects of the fin geometry over the spatial-averaged Nusselt number ( ) is investigated for three different Reynolds numbers (ReH = 10, 102 and 103). The conservation equations of mass, momentum and energy were numerically solved with the Finite Volume Method. Results showed that both degrees of freedom (H1/L1 and S/A1/2) had a strong influence over , mainly for higher magnitudes of Reynolds number. Moreover, the best thermal performance is reached when the fin is placed near the upper surface of the cavity for an intermediate ratio between height and length of rectangular fin, more precisely when (S/A1/2)o = 0.9 and (H1/L1)oo = 2.0.

Thermal performance due to magnetohydrodynamics mixed convection flow in a triangular cavity with circular obstacle

2020 ◽  
Vol 31 ◽  
pp. 101702 ◽  
Author(s):  
Feroz Ahmed Soomro ◽  
Rizwan Ul Haq ◽  
Ebrahem A. Algehyne ◽  
Iskander Tlili
Keyword(s):  
Mixed Convection ◽  
Thermal Performance ◽  
Convection Flow ◽  
Mixed Convection Flow

Nonlinear stability of mixed convection flow under non-Boussinesq conditions. Part 2. Mean flow characteristics

1999 ◽  
Vol 398 ◽  
pp. 87-108 ◽  
Author(s):  
S. A. SUSLOV ◽  
S. PAOLUCCI
Keyword(s):  
Mixed Convection ◽  
Mass Flux ◽  
Flow Characteristics ◽  
Vertical Channel ◽  
Physical Nature ◽  
Reynolds Numbers ◽  
Convection Flow ◽  
Mixed Convection Flow ◽  
Mean Flow ◽  
Wide Range

Based on amplitude expansions developed in Part 1 (Suslov & Paolucci 1999), we examine the mean flow characteristics of non-Boussinesq mixed convection flow of air in a vertical channel in the vicinity of bifurcation points for a wide range of temperature differences between the walls, and Grashof and Reynolds numbers. The constant mass flux and constant pressure gradient formulations are shown to lead to qualitatively similar, but quantitatively different, results. The physical nature of the distinct shear and buoyancy disturbances is investigated, and detailed mean flow and energy analyses are presented. The variation of the total mass of fluid in a flow domain as disturbances develop is discussed. The average Nusselt number and mass flux are estimated for supercritical regimes for a wide range of governing parameters.

scholarly journals Mhd Mixed Convection in Copper-Water Nanofluid Filled Lid-Driven Square Cavity Containing Multiple Adiabatic Obstacles with Discrete Heating

2020 ◽  
Vol 25 (2) ◽  
pp. 57-74
Author(s):  
R.S.R. Gorla ◽  
S. Siddiqa ◽  
A.A. Hasan ◽  
T. Salah ◽  
A.M. Rashad
Keyword(s):  
Heat Source ◽  
Mixed Convection ◽  
Convection Flow ◽  
Square Cavity ◽  
Left Wall ◽  
Simpler Algorithm ◽  
Position Parameter ◽  
The Right ◽  
Volume Method ◽  
Good Agreement

AbstractThe objective of the present work is to investigate the influence of nanoparticles of copper within the base fluid (water) on magneto-hydrodynamic mixed-convection flow in a square cavity with internal generation. A control finite volume method and SIMPLER algorithm are used in the numerical calculations. The geometry is a lid-driven square cavity with four interior square adiabatic obstacles. A uniform heat source is located in a part of the left wall and a part of the right wall of the enclosure is maintained at cooler temperature while the remaining parts of the two walls are thermally insulated. Both the upper and bottom walls of the cavity are considered to be adiabatic. A comparison with previously published works shows a very good agreement. It is observed that the Richardson number, Ri, significantly alters the behavior of streamlines when increased from 0.1 to 100.0. Also, the heat source position parameter, D, significantly changes the pattern of isotherms and its strength shifted when D moves from 0.3 to 0.7.

scholarly journals CONSTRUCTAL DESIGN OF A TUBULAR ARRAY SUBJECTED TO FORCED CONVECTION

2015 ◽  
Vol 14 (1) ◽  
pp. 16
Author(s):  
V. A. Pedrotti ◽  
J. A. Souza ◽  
E. D. Dos Santos ◽  
L. A. Isoldi
Keyword(s):  
Thermal Performance ◽  
Mesh Generation ◽  
Constructal Theory ◽  
Forced Flow ◽  
Constructal Design ◽  
Fluent Software ◽  
Energy Equations ◽  
Volume Method ◽  
Study Setting ◽  
Tubular Array

In this work a tubular array (four tubes) subjected to a transverse forced flow is analyzed in terms of thermal performance. Taking into account that there are two main assembles usually used in heat exchanger equipment (aligned and staggered), and that there exist an uncountable number of possible assembles for an array of tubes, present work proposes to use the Constructal Theory to build an optimized assemble. The distance between tubes (p), and the region where tubes can be positioned are the geometric constraint of the problem. Four values for p were considered: p = 1.25D (tube diameter), p = 1.5D, p = 2D, p is free (no restriction). Fluid flow is considered bi-dimensional, incompressible and laminar with ReD = 10 and Pr = 0.71. Mass, momentum and energy equations were solved by the Finite Volume Method (FVM) using FLUENT software. Geometry creation and mesh generation were performed with GMSH software while VISIT software was used for the post processing. Results have shown that imposing no restriction to tube positioning do not necessarily lead to best system thermal performance. In this particular study, setting p = 2D has resulted in best thermal performance.

Experimental Investigations Into Mixed Convection About a Horizontal Cylinder: Part A — Heat Transfer Using Digital Speckle Pattern Interferometry

2005 ◽  
Author(s):  
Vanessa Egan ◽  
Tara Dalton ◽  
Mark R. D. Davies ◽  
Maurice Whelan
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Speckle Pattern ◽  
Cross Flow ◽  
Reynolds Numbers ◽  
Inertia Force ◽  
Convection Flow ◽  
Digital Speckle Pattern Interferometry ◽  
Unsteady Mixed Convection ◽  
Digital Speckle

Mixed convection heat transfer is commonly found in many engineering applications and is particularly relevant to the cooling of electronic components but despite this, the physics of this heat transfer regime is not fully understood. This paper presents an experimental study into buoyancy opposing cross flow, a commonly found mixed convection regime. The experimental configuration comprised a long heated cylinder suspended in a glass walled enclosure. The airflow within the enclosure was controlled using a baffled axial fan to give Reynolds numbers in the range of 32–89. The mean Nusselt numbers were measured about the cylinder for Rayleigh numbers between 1.7E+04–4.0E+04. For the acquisition of full field data the optical techniques, digital speckle pattern interferometry (DSPI) and phase measurement interferometry (PMI), were employed. Buoyancy opposing cross flow created an unsteady flow field about the cylinder at low Reynolds numbers and steady state temperatures. DSPI enabled real-time interferograms to be recorded and results are presented in the form of instantaneous interferograms showing the high frequency fluctuations of the temperature field about the cylinder. Attention is focused on understanding the trend in mean heat transfer values resulting from an increased inertia force and thus providing a significant insight into unsteady mixed convection flow.

Instability and Heat Transfer in Mixed Convection Flow in a Horizontal Duct With Discrete Heat Sources

2001 ◽  
Author(s):  
Qinghua Wang ◽  
Yogesh Jaluria
Keyword(s):  
Mixed Convection ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Forced Flow ◽  
Bottom Surface ◽  
Convection Flow ◽  
Heat Sources ◽  
Mixed Convection Flow ◽  
Mean Velocity ◽  
Low Reynolds Numbers

Abstract Three dimensional mixed convection flow in a horizontal rectangular duct at low Reynolds numbers 5 ≤ Re ≤ 100 has been investigated numerically. Multiple strip heat sources are flushed-mounted on the bottom surface, modeling IC chips on PCBs. Two different flow patterns were observed. For Re ≥ 20, and Gr ≤ 1.5 × 104, only steady longitudinal rolls appear in the channel. The discontinuous deployment of heat sources on the bottom makes the longitudinal rolls expand and shrink periodically. The unsteady flow consists of steady longitudinal rolls near the side walls and traveling transverse rolls at the core region of the channel. The traveling velocity of the transverse rolls was found to be equal to the mean velocity of the forced flow. The implications of these observations to the cooling of electronic equipment are discussed.

Fluid Flow and Heat Transfer in an Annulus With Ribs on the Rotating Inner Cylinder Surface

2020 ◽  
Vol 12 (4) ◽  
Author(s):  
S. Gokul ◽  
M. Deepu
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Thermal Performance ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Reynolds Numbers ◽  
Cylinder Surface ◽  
Turbulent Fluid Flow ◽  
Cylindrical Annulus ◽  
Volume Method

Abstract Numerical studies on heat transfer in Taylor-Couette-Poiseuille flow in a cylindrical annulus with ribs mounted on the rotating inner cylinder are presented. The present study focuses on two different types of ribs, namely, longitudinal ribs and helical ribs. Three-dimensional, steady, incompressible, turbulent fluid flow is solved using a semi-implicit method for pressure linked equations (SIMPLE) algorithm based finite volume method. The numerical solution method is validated using two sets of benchmark experimental data. Extensive numerical computations are carried out at various Reynolds numbers (2100 &lt; Re &lt; 2400) and modified Taylor numbers (30,000 &lt; Tam &lt; 90,000) for annulus with and without ribs. Ribs enhance the transport of heat and momentum by inducing more vorticity and turbulence in the flow. The overall performance is presented in terms of thermal performance factor (TPF), which takes in to account the heat transfer as well as pressure drop in the ribbed annulus. Helical ribs are found to offer superior thermal performance than its longitudinal counterpart.

Sign in / Sign up

Export Citation Format

Share Document