Arul K Prakash

Numerical simulation of fluid flow through various configurations like decelerated, free vortex, accelerated and spiral casing with different aspect ratios (AR) based on cross section has been studied using finite element method. An explicit Eulerian velocity correction scheme has been deployed to solve the Reynolds averaged Navier-stokes equations. The simulations have been performed to describe the fluid flow in high Reynolds number (106) regime. A streamline upwind Petrov Galerkin technique has been used for discretising governing equations. The pressure distribution inside the spiral casing has been studied. Total head loss for all configurations with various aspect ratios is modeled using response surface approximation. Subsequently, unconstrained non-linear minimization method is implemented to obtain optimum spiral casing by minimizing the total head loss.

In this study, natural-convection heat transfer characteristics of Al2O3-water nanofluid flow through a homogeneous porous medium embedded in a square cavity with several pairs of heaters and coolers located inside are investigated numerically. The two-dimensional equations governing the nanofluid flow and heat transfer through the porous medium are discretized using Streamline Upwind Petrov-Galerkin (SUPG) based Finite Element Method (FEM). The generalized Darcy-Brinkman-Forchheimer's porous medium model is used in this analysis. The average Nusselt number in the cases of the base fluid without a porous medium, of a nanofluid without a porous medium, and a nanofluid with a porous medium are compared for different Rayleigh numbers. It is found that in the case of the nanofluid with a porous medium the highest value of average Nusselt number was obtained. In addition to this, the effect of the Darcy number and the porosity on the pattern of streamlines and isotherms is investigated. It is also observed that the average Nusselt number increases with increasing Darcy number and decreases with increasing porosity and nanoparticle volume fraction.

In this paper, fluid flow and thermal characteristics associated with natural convection heat transfer in a porous enclosure containing high temperature heat sources placed on top and bottom walls are studied. For this purpose, two-dimensional, time-dependent Navier-Stokes equations with Darcy-Brinkman-Forchheimer terms are solved in a Cartesian framework by using Streamline Upwind Petrov-Galerkin (SUPG) based finite element method. The effect of heat sources on flow pattern, entropy generation and temperature distribution are studied for different Darcy numbers, porosities and Rayleigh numbers. The results show that maximum entropy generation due to heat transfer irreversibility is observed in the vicinity of heat sources due to the presence of high thermal gradient. The global entropy generation due to fluid friction is found to increase in convection dominated regime. It is also observed that with increasing Darcy number, porosity and Rayleigh number the surface averaged Nusselt number for both top and bottom heat sources is increased. © 2013 Elsevier Ltd. All rights reserved.

Numerical simulations of fluid flow through various spiral casings like accelerated, free vortex and decelerated type with different aspect ratios (AR) are carried out to construct surrogates. These surrogates are utilised for analysing design sensitivity of spiral casing to obtain its optimal design. Responses like spiral velocity coefficient, total pressure loss and average radial velocities obtained from numerical computations are used for surrogates’ construction. Different surrogate models considered are Kriging, polynomial response surface, support vector regression and weighted average surrogate. Surrogates are validated using average error analysis for the selection of best surrogate. Weighted average surrogate performs well in most of the cases among all responses. Near optimal solutions obtained from the best surrogates are proposed.