Leo Lukose

Bio: Leo Lukose is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Natural convection & Convection. The author has an hindex of 5, co-authored 14 publications receiving 62 citations.

Role of multiple discrete heaters to minimize entropy generation during natural convection in fluid filled square and triangular enclosures

Abstract: The discrete heating strategy has been identified as an energy efficient method. The current work is aimed at achieving a thermally efficient triangular-design 1 (regular isosceles triangle), triangular-design 2 (inverted isosceles triangle) and square enclosures based on the entropy generation studies involving strategic positioning of the double heaters along each side wall (case 1: larger heater in lower half and smaller heater in central half, case 2: larger heater in central half and smaller heater in lower half, case 3: two heaters of identical lengths located at central and lower halves) for Pr = 0.015 and 7.2 involving Ra = 10 3 – 10 5 . The numerical results of the cases 1–3 have been further compared with the case involving single heater along each side wall (case 0). Galerkin finite element method is implemented for the accurate evaluation of the entropy generation terms based on elemental basis set. Cases 1–3 exhibit lower entropy generation and higher heat transfer rates in the convection dominant regime ( Ra = 10 5 ) compared to the case 0. Overall, case 3 is concluded to be optimal based on higher rate of heat transfer and lower entropy generation.

Role of multiple solar heaters along the walls for the thermal management during natural convection in square and triangular cavities

Abstract: The role of multiple discrete solar heaters have been studied for energy efficiency in the heating of fluids. Current work involves natural convection studies with the various locations of the double heat sources along each side wall of the triangular-design 1 (regular isosceles triangle), triangular-design 2 (inverted isosceles triangle) and square enclosures for various cases (case 1: larger heater in lower half and smaller heater in central half, case 2: larger heater in central half and smaller heater in lower half, case 3: two heaters of identical lengths are located at the central and lower halves) involving various fluids ( P r = 0.015 and 7.2) for various Rayleigh numbers, 10 3 ≤ R a ≤ 10 5 . The thermal mixing and energy flow in the cavities are visualized using the mathematical tool of heatlines. Also, the overall rate of heat transfer in conduction and convection dominant regimes is evaluated using Nusselt numbers (average and local). The case 2 discrete heating configuration is inferred as the optimal heating configuration based on the larger zone of uniform temperature and thermal mixing. Also, the thermal management is significantly improved in triangular-design 2 and square cavities.

Numerical heat flow visualization analysis on enhanced thermal processing for various shapes of containers during thermal convection

Abstract: The purpose of this paper is to study thermal (natural) convection in nine different containers involving the same area (area= 1 sq. unit) and identical heat input at the bottom wall (isothermal/sinusoidal heating). Containers are categorized into three classes based on geometric configurations [Class 1 (square, tilted square and parallelogram), Class 2 (trapezoidal type 1, trapezoidal type 2 and triangle) and Class 3 (convex, concave and triangle with curved hypotenuse)].,The governing equations are solved by using the Galerkin finite element method for various processing fluids (Pr = 0.025 and 155) and Rayleigh numbers (103 ≤ Ra ≤ 105) involving nine different containers. Finite element-based heat flow visualization via heatlines has been adopted to study heat distribution at various sections. Average Nusselt number at the bottom wall ( Nub¯) and spatially average temperature (θ^) have also been calculated based on finite element basis functions.,Based on enhanced heating criteria (higher Nub¯ and higher θ^), the containers are preferred as follows, Class 1: square and parallelogram, Class 2: trapezoidal type 1 and trapezoidal type 2 and Class 3: convex (higher θ^) and concave (higher Nub¯).,The comparison of heat flow distributions and isotherms in nine containers gives a clear perspective for choosing appropriate containers at various process parameters (Pr and Ra). The results for current work may be useful to obtain enhancement of the thermal processing rate in various process industries.,Heatlines provide a complete understanding of heat flow path and heat distribution within nine containers. Various cold zones and thermal mixing zones have been highlighted and these zones are found to be altered with various shapes of containers. The importance of containers with curved walls for enhanced thermal processing rate is clearly established.

Role of multiple discrete heaters on the entropy generation during natural convection in porous square and triangular enclosures

Abstract: Comparative study based on the entropy generation analysis has been carried out within porous square and triangular (design 1 and 2) enclosures subjected to discrete heating involving double heater...

Numerical visualization via heatlines for natural convection in porous bodies of rhombic shapes subjected to thermal aspect ratio-based heating of walls

Abstract: Visualization of heat flow and trajectories has been employed during buoyancy induced (natural) convection within porous rhombic 2D cavities of different base angles involving various inten...

Introduction to the Finite Element Method

Abstract: This chapter introduces the finite element method (FEM) as a tool for solution of classical electromagnetic problems. Although we discuss the main points in the application of the finite element method to electromagnetic design, including formulation and implementation, those who seek deeper understanding of the finite element method should consult some of the works listed in the bibliography section.

Shape effects of Copper-Oxide (CuO) nanoparticles to determine the heat transfer filled in a partially heated rhombus enclosure: CVFEM approach

Abstract: In this article, shape effects of copper-Oxide are analyzed for heat transfer characteristics within the partially heated rhombus enclosure. Additionally, a circular barrier is that have three diverse constraints (adiabatic, cold and hot) is placed at the center of the rhombus. Water is used as a base fluid to constitute the working nanofluid (CuO-water). Heat transfer within the enclosure happens due to a differential temperature at the cavity walls. The governing partial differential equations include conservation of energy, momentum and mass which are numerically solved via CVFEM. The study concludes that heat transfer rate is ascended owing to ascendant in Rayleigh number and descended owing to ascendant in nanoparticles volume fraction. The study further discloses that the maximum heat transfer rate is ascended owing to ascendant in nanoparticles shape factor. In order to determine the stream function and isotherms, various physical domain has been selected for each emerging parameter such as nanoparticles' shape factor, Rayleigh number, and nanoparticle volume fraction. It is concluded that the heat transfer rate is maximum using Platelet shaped nanoparticles.

A Review on the Control Parameters of Natural Convection in Different Shaped Cavities with and without Nanofluid

Abstract: Natural convection in cavities is an interesting subject for many researchers Especially, in recent years, the number of articles written in this regard has grown enormously This work provides a review of recent natural convection studies At first, experimental studies were reviewed and, then, numerical studies were examined Then, the articles were classified based on effective parameters In each section, numerical studies were examined the parameters added to the cavity such as magnetic forces, fin, porous media and cavity angles Moreover, studies on non-rectangular cavities were investigated Free convection in enclosures depends more on the fluid velocity relative to the forced convection, leading to the opposite effect of some parameters that should essentially enhance rate of heat transfer Nanoparticle addition, magnetic fields, fins, and porous media may increase forced convection However, they can reduce free convection due to the reduction in fluid velocity Thus, these parameters need more precision and sometimes need the optimization of effective parameters

MHD natural convection of Cu/H2O nanofluid in a horizontal semi-cylinder with a local triangular heater

Abstract: Purpose The purpose of this study is to investigate free convection of copper-water nanofluid in an upper half of circular horizontal cylinder with a local triangular heater under the effects of uniform magnetic field and cold cylinder shell using control volume finite element method (CVFEM). Design/methodology/approach Governing equations formulated in dimensionless stream function, vorticity and temperature variables using the single-phase nanofluid model with Brinkman correlation for the effective dynamic viscosity and Hamilton and Crosser model for the effective thermal conductivity have been solved numerically by CVFEM. Findings The impacts of control parameters such as the Rayleigh number, Hartmann number, nanoparticles volume fraction, local triangular heater size, shape factor on streamlines and isotherms as well as local and average Nusselt numbers have been examined. The outcomes indicate that the average Nusselt number is an increasing function of the Rayleigh number, shape factor and nanoparticles volume fraction, while it is a decreasing function of the Hartmann number. Originality/value A complete study of the free convection of copper-water nanofluid in an upper half of circular horizontal cylinder with a local triangular heater under the effects of uniform magnetic field and cold cylinder shell using CVFEM is addressed.