scholarly journals Constructal theory of parabolic scaling

2012 ◽  
Author(s):  
S. Périn
Keyword(s):  
Constructal Theory ◽  
Parabolic Scaling

CONSTRUCTAL THEORY APPLIED TO CONSTRUCTION OF FINS ARRANGEMENT MOUNTED IN A MICROCHANNEL SUBJECTED TO LAMINAR FORCED CONVECTIVE FLOWS

2020 ◽  
Author(s):  
Rafael San Martin Moreira ◽  
Liércio Isoldi ◽  
jeferson Avila Souza ◽  
Elizaldo dos Santos
Keyword(s):  
Constructal Theory ◽  
Convective Flows

scholarly journals Multiscale modeling of glioma pseudopalisades: contributions from the tumor microenvironment

2021 ◽  
Vol 82 (6) ◽  
Author(s):  
Pawan Kumar ◽  
Jing Li ◽  
Christina Surulescu
Keyword(s):  
Multiscale Modeling ◽  
Reaction Diffusion ◽  
Tumor Grade ◽  
Invasive Potential ◽  
Macroscopic System ◽  
Active Particles ◽  
Reaction Diffusion Model ◽  
Different Types ◽  
Parabolic Scaling ◽  
Parameter Ranges

AbstractGliomas are primary brain tumors with a high invasive potential and infiltrative spread. Among them, glioblastoma multiforme (GBM) exhibits microvascular hyperplasia and pronounced necrosis triggered by hypoxia. Histological samples showing garland-like hypercellular structures (so-called pseudopalisades) centered around the occlusion site of a capillary are typical for GBM and hint on poor prognosis of patient survival. We propose a multiscale modeling approach in the kinetic theory of active particles framework and deduce by an upscaling process a reaction-diffusion model with repellent pH-taxis. We prove existence of a unique global bounded classical solution for a version of the obtained macroscopic system and investigate the asymptotic behavior of the solution. Moreover, we study two different types of scaling and compare the behavior of the obtained macroscopic PDEs by way of simulations. These show that patterns (not necessarily of Turing type), including pseudopalisades, can be formed for some parameter ranges, in accordance with the tumor grade. This is true when the PDEs are obtained via parabolic scaling (undirected tissue), while no such patterns are observed for the PDEs arising by a hyperbolic limit (directed tissue). This suggests that brain tissue might be undirected - at least as far as glioma migration is concerned. We also investigate two different ways of including cell level descriptions of response to hypoxia and the way they are related .

Bejan’s Constructal Theory Analysis of Gas-Liquid Cooled Finned Modules

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
Giulio Lorenzini ◽  
Simone Moretti
Keyword(s):  
Thermal Behavior ◽  
Heat Exchangers ◽  
High Performance ◽  
Numerical Study ◽  
Constructal Theory ◽  
Electronic Components ◽  
Theory Analysis ◽  
Pressure Losses ◽  
Different Types ◽  
Overall Performance

High performance heat exchangers represent nowadays the key of success to go on with the trend of miniaturizing electronic components as requested by the industry. This numerical study, based on Bejan’s Constructal theory, analyzes the thermal behavior of heat removing fin modules, comparing their performances when operating with different types of fluids. In particular, the simulations involve air and water (as representative of gases and liquids), to understand the actual benefits of employing a less heat conductive fluid involving smaller pressure losses or vice versa. The analysis parameters typical of a Constructal description (such as conductance or Overall Performance Coefficient) show that significantly improved performances may be achieved when using water, even if an unavoidable increase in pressure losses affects the liquid-refrigerated case. Considering the overall performance: if the parameter called Relevance tends to 0, air prevails; if it tends to 1, water prevails; if its value is about 0.5, water prevails in most of the case studies.

Performance Improvement of a Circular MCFC Through Optimal Design of the Fluid Distribution System

2011 ◽  
Author(s):  
Adriano Sciacovelli ◽  
Vittorio Verda ◽  
Cristina Amelio ◽  
Carlo Repetto ◽  
Gustavo Diaz
Keyword(s):  
Economic Development ◽  
Fuel Cell ◽  
Power Density ◽  
Distribution System ◽  
New Technologies ◽  
Molten Carbonate Fuel Cell ◽  
Constructal Theory ◽  
Fluid Distribution ◽  
Molten Carbonate ◽  
Original Design

In this paper, the prototype of a circular Molten Carbonate Fuel Cell (MCFC) built in the laboratories of FN SpA Nuove Tecnologie e Servizi Avanzati is analyzed using a tridimensional computational fluid dynamic (CFD) model. The prototype is the result of FN and Politecnico di Torino activities developed for the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) within the framework of Ministry of Economic Development, MSE-ENEA. This model considers heat, mass and current transfer as well as chemical and electrochemical reactions. The results show that some inhomogeneous distributions in the reactants, causing non-optimal use of the reactant surfaces. An effective way to improve the distribution in current density consists in tracing tree shaped channels on the surface onto the distribution porous medium. In this paper Y shaped channels are adopted to improve the distribution of gas within the fuel cell and consequently to enhance the performance of the original design of the fuel cell. In addition, the configuration of the outlet of the anodic compartment is also investigated in order to further increase the performance of the fuel cell. The geometrical parameter identifying the topology of distribution channels are chosen accordingly to the constructal theory. The results show that significant improvements can be achieved. Power density is increased of about 6% when the tree-shaped channel is adopted. If a double anodic inlet is also considered the enhancement in the power density is of about 11% with respect to the initial configuration.

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.

Constructal Theory in Heat Transfer

2018 ◽  
pp. 329-360 ◽  
Author(s):  
Luiz A. O. Rocha ◽  
S. Lorente ◽  
A. Bejan
Keyword(s):  
Heat Transfer ◽  
Constructal Theory
Sign in / Sign up

Export Citation Format

Share Document