scholarly journals CONSTRUCTAL THEORY APPLIED TO THE GEOMETRIC OPTIMIZATION OF ELLIPTICAL CAVITIES INTO A SOLID CONDUCTING WALL

2008 ◽  
Vol 7 (2) ◽  
pp. 81
Author(s):  
L. A. O. Rocha ◽  
C. Biserni ◽  
E. Lorenzini
Keyword(s):  
Solid Wall ◽  
Thermal Conditions ◽  
Geometric Optimization ◽  
Constructal Theory ◽  
Design Parameters ◽  
Cavity Volume ◽  
Cavity Shape ◽  
Elliptical Cavity ◽  
Conducting Wall ◽  
Geometrical Shapes

This work reports, according to Bejan’s Constructal theory, the geometric optimization of an elliptical cavity that intrudes into a solid conducting wall. The objective is to minimize the global thermal resistance between the solid and the cavity. There is uniform heat generation on the solid wall. The cavity is optimized for two sets of thermal conditions: isothermal cavity and cavity bathed by a steady stream of fluid. The solid conducting wall is isolated on the external perimeter. The total volume and the elliptical cavity volume are fixed while the geometry of the cavity is free to vary. The results show that the optimized geometrical shapes are relatively robust, i.e., insensitive to changes in some of the design parameters: the cavity shape is optimal when penetrates the conducting wall almost completely.

scholarly journals CONSTRUCTAL DESIGN APPLIED TO THE STUDY OF CAVITIES INTO A SOLID CONDUCTING WALL

2007 ◽  
Vol 6 (1) ◽  
pp. 41
Author(s):  
L. A. O. Rocha ◽  
G. C. Montanari ◽  
E. D. Dos Santos ◽  
A. Da S. Rocha
Keyword(s):  
Solid Wall ◽  
Rectangular Cavity ◽  
The Other ◽  
Cavity Volume ◽  
Cavity Shape ◽  
Constructal Design ◽  
Elliptical Cavity ◽  
Conducting Wall ◽  
Aspect Ratios ◽  
Better Than

This paper relies on the Constructal Design to optimize the geometry of a cavity that penetrates into a solid conducting wall. The objective is to minimize the global thermal resistance between the solid and the cavity.  There is uniform heat generation on the solid wall. We studied three shapes of the cavity: rectangular, triangular, and elliptical. The total volume and the cavity volume are fixed with variable aspect ratios. The cavity shape is optimal when it penetrates the conducting wall completely. The rectangular cavity performs better than the elliptical and triangular ones. On the other side, the elliptical cavity has better performance than the triangular one.  We also optimized a first construct, i.e., a cavity shaped as T. The performance of the T-shaped cavity is superior to that of the rectangular cavity optimized in the first part of the paper.

Geometric Optimization of C-Shaped Cavities According to Bejan's Theory: General Review and Comparative Study

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
G. Lorenzini ◽  
C. Biserni ◽  
L. A. O. Rocha
Keyword(s):  
Aspect Ratio ◽  
Solid Wall ◽  
Convection Heat Transfer ◽  
Internal Heat ◽  
Thermal Conditions ◽  
Geometric Optimization ◽  
Square Cavity ◽  
Conducting Wall ◽  
Optimal Shapes ◽  
The One

The aim of this paper is to consider, by means of the numerical investigation, the geometric optimization of a cavity that intrudes into a solid with internal heat generation. The objective is to minimize the maximal dimensionless excess of temperature between the solid and the cavity. The cavity is rectangular, with fixed volume and variable aspect ratio. The cavity shape is optimized for two sets of boundary conditions: isothermal cavity and cavity cooled by convection heat transfer. The optimal cavity is the one that penetrates almost completely the conducting wall and proved to be practically independent of the boundary thermal conditions, for the external ratio of the solid wall smaller than 2. As for the convective cavity, it is worthy to know that for values of H/L greater than 2, the best shape is no longer the one that penetrates completely into the solid wall, but the one that presents the largest cavity aspect ratio H0/L0. Finally, when compared with the optimal cavity ratio calculated for the isothermal C-shaped square cavity, the cavities cooled by convection highlight almost the same optimal shape for values of the dimensionless group λ ≤ 0.01. Both cavities, isothermal and cooled by convection, also present similar optimal shapes for ϕ0 < 0.3 and ϕ0 > 0.7. However, in the range 0.3 ≤ ϕ0 ≤ 0.7, the ratio (H0/L0)opt calculated for the cavities cooled by convection is greater than the one presented by isothermal cavities. This difference is approximately 17% when λ = 0.1 and ϕ0 = 0.7, and 20% for λ = 1 and ϕ0 = 0.5.

scholarly journals GEOMETRIC OPTIMIZATION OF “+”-SHAPED CAVITY USING CONSTRUCTAL THEORY

2017 ◽  
Vol 16 (1) ◽  
pp. 75
Author(s):  
P. A. Avendaño ◽  
J. A. Souza ◽  
D. F. Adamatti ◽  
E. D. dos Santos
Keyword(s):  
Solid Body ◽  
Degrees Of Freedom ◽  
Internal Heat ◽  
Thermal Conditions ◽  
Geometric Optimization ◽  
Optimal Performance ◽  
Constructal Theory ◽  
Maximum Temperature ◽  
Constructal Design ◽  
Better Than

In this work it is applied the Constructal Theory for the study of the geometry of an “+”-shaped isothermal cavity inserted in a conductive solid body. Main goal is to minimize the maximum temperature in the solid. The total volume of the solid and the total volume of the cavity are kept fixed while the dimensions of the cavity geometry vary according to constraints and degrees of freedom defined by the Constructal Design. The solid body has internal heat generation and its external surfaces are insulated. Cavity walls are isothermal with constant temperature Tmin. Obtained results indicate that the optimal performance of “+”-shape cavity is 37.2% better that the optimal performance of “C”-shape cavity and 10.8% better than the “T”-shaped cavity for the same thermal conditions.

scholarly journals Optimal Pressure Boundary Control of Steady Multiscale Fluid-Structure Interaction Shell Model Derived from Koiter Equations

Fluids ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 149
Author(s):  
Andrea Chierici ◽  
Leonardo Chirco ◽  
Sandro Manservisi
Keyword(s):  
Optimal Control ◽  
Solid Wall ◽  
Fluid Structure Interaction ◽  
Computational Cost ◽  
Robin Boundary Condition ◽  
Design Parameters ◽  
Fluid Structure ◽  
Control Approach ◽  
Structure Interaction ◽  
Fluid Boundary

Fluid-structure interaction (FSI) problems are of great interest, due to their applicability in science and engineering. However, the coupling between large fluid domains and small moving solid walls presents numerous numerical difficulties and, in some configurations, where the thickness of the solid wall can be neglected, one can consider membrane models, which are derived from the Koiter shell equations with a reduction of the computational cost of the algorithm. With this assumption, the FSI simulation is reduced to the fluid equations on a moving mesh together with a Robin boundary condition that is imposed on the moving solid surface. In this manuscript, we are interested in the study of inverse FSI problems that aim to achieve an objective by changing some design parameters, such as forces, boundary conditions, or geometrical domain shapes. We study the inverse FSI membrane model by using an optimal control approach that is based on Lagrange multipliers and adjoint variables. In particular, we propose a pressure boundary optimal control with the purpose to control the solid deformation by changing the pressure on a fluid boundary. We report the results of some numerical tests for two-dimensional domains to demonstrate the feasibility and robustness of our method.

scholarly journals A New Approach for Design Optimization and Parametric Analysis of Symmetric Compound Parabolic Concentrator for Photovoltaic Applications

2021 ◽  
Vol 13 (9) ◽  
pp. 4606
Author(s):  
Faisal Masood ◽  
Perumal Nallagownden ◽  
Irraivan Elamvazuthi ◽  
Javed Akhter ◽  
Mohammad Azad Alam
Keyword(s):  
Parametric Analysis ◽  
Concentration Ratio ◽  
Synergistic Effects ◽  
Geometric Optimization ◽  
Design Parameters ◽  
Imaging Device ◽  
Compound Parabolic Concentrator ◽  
Photovoltaic Applications ◽  
Half Angle ◽  
The Impact

A compound parabolic concentrator (CPC) is a non-imaging device generally used in PV, thermal, or PV/thermal hybrid systems for the concentration of solar radiation on the target surface. This paper presents the geometric design, statistical modeling, parametric analysis, and geometric optimization of a two-dimensional low concentration symmetric compound parabolic concentrator for potential use in building-integrated and rooftop photovoltaic applications. The CPC was initially designed for a concentration ratio of “2×” and an acceptance half-angle of 30°. A MATLAB code was developed in house to provoke the CPC reflector’s profile. The height, aperture width, and concentration ratios were computed for different acceptance half-angles and receiver widths. The interdependence of optical concentration ratio and acceptance half-angle was demonstrated for a wide span of acceptance half-angles. The impact of the truncation ratio on the geometric parameters was investigated to identify the optimum truncation position. The profile of truncated CPC for different truncation positions was compared with full CPC. A detailed statistical analysis was performed to analyze the synergistic effects of independent design parameters on the responses using the response surface modeling approach. A set of optimized design parameters was obtained by establishing specified optimization criteria. A 50% truncated CPC with an acceptance half-angle of 21.58° and receiver width of 193.98 mm resulted in optimum geometric dimensions.

scholarly journals CONSTRUCTAL DESIGN AND SIMULATED ANNEALING EMPLOYED FOR GEOMETRIC OPTIMIZATION OF A Y-SHAPED CAVITY INTRUDED INTO CONDUCTIVE WALL

2015 ◽  
Vol 14 (1) ◽  
pp. 79
Author(s):  
G. V. Gonzales ◽  
E. D. Dos Santos ◽  
L. R. Emmendorfer ◽  
L. A. Isoldi ◽  
E. S. D. Estrada ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Simulated Annealing ◽  
Solid Wall ◽  
Internal Heat ◽  
Optimization Methods ◽  
Optimization Method ◽  
Internal Heat Generation ◽  
Geometric Optimization ◽  
Constructal Design ◽  
Optimal Shapes

he problem study here is concerned with the geometrical evaluation of an isothermal Y-shaped cavity intruded into conducting solid wall with internal heat generation. The cavity acts as a sink of the heat generated into the solid. The main purpose here is to minimize the maximal excess of temperature (θmax) in the solid. Constructal Design, which is based on the objective and constraints principle, is employed to evaluate the geometries of Y-shaped cavity. Meanwhile, Simulated Annealing (SA) algorithm is employed as optimization method to seek for the best shapes. To validate the SA methodology, the results obtained with SA are compared with those achieved with Genetic Algorithm (GA) and Exaustive Search (ES) in recent studies of literature. The comparison between the optimization methods (SA, GA and ES) showed that Simulated Annealing is highly effective in the search for the optimal shapes of the studied case.

scholarly journals Constructal design of isothermal X-shaped cavities

2014 ◽  
Vol 18 (2) ◽  
pp. 349-356 ◽  
Author(s):  
G. Lorenzini ◽  
C. Biserni ◽  
F.B. Link ◽  
Dos Santos ◽  
L.A. Isoldi ◽  
...  
Keyword(s):  
Heat Generation ◽  
Solid Body ◽  
Outer Surface ◽  
Area Fraction ◽  
Cavity Volume ◽  
Constructal Design ◽  
Conducting Wall ◽  
And Performance ◽  
Optimal Configurations ◽  
Better Than

This paper applies Constructal design to study the geometry of a X-shaped cavity that penetrates into a solid conducting wall. The objective is to minimize the maximal dimensionless excess of temperature between the solid body and the cavity. There is uniform heat generation on the solid body. The total volume and the cavity volume are fixed, but the geometric lengths and thickness of the X-shaped cavity can vary. The cavity surfaces are isothermal while the solid body has adiabatic conditions on the outer surface. The emerged optimal configurations and performance are reported graphically. When compared to the Y- and C- and H-, the X-shaped cavity performs approximately 53% better than the Y-shaped cavity and 68% better than the C-shaped cavity for the area fraction ? = 0.05, while its performance is 22% inferior to the performance of the H-shaped cavity for the area fraction ? = 0.1. The results indicate that the increase of the complexity of the cavity geometry can facilitate the access of heat currents and improve the performance of the cavities.

Numerical Analysis of the Effect of Diffusion and Creep Flow on Cavity Growth

2007 ◽  
Author(s):  
Frederick W. Brust ◽  
Joonyoung Oh
Keyword(s):  
Growth Rate ◽  
Numerical Method ◽  
Cavity Growth ◽  
Volume Growth ◽  
Numerical Results ◽  
Shape Evolution ◽  
Cavity Volume ◽  
Cavity Shape ◽  
Cavity Growth Rate ◽  
Fully Coupled

In this paper, intergranular cavity growth in regimes, where both surface diffusion and deformation enhanced grain boundary diffusion are important, is studied. In order to continuously simulate the cavity shape evolution and cavity growth rate, a fully-coupled numerical method is proposed. Based on the fully-coupled numerical method, a gradual cavity shape change is predicted and this leads to an adverse effect on the cavity growth rates. As the portion of the cavity volume growth due to jacking and viscoplastic deformation in the total cavity volume growth increases, the initially spherical cavity evolves to V-shaped cavity. The numerical results are physically more realistic compared to results in the previous studies. The present numerical results suggest that the cavity shape evolution and cavity growth rate based on an assumed cavity shape, whether spherical or crack-like, cannot be used in this regime due to transitional coupled growth mechanisms.

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