Goutam Dutta

Bio: Goutam Dutta is an academic researcher from Indian Institutes of Technology. The author has contributed to research in topics: Supercritical fluid & Natural circulation. The author has an hindex of 7, co-authored 26 publications receiving 211 citations. Previous affiliations of Goutam Dutta include University of Western Ontario & Indian Institute of Technology Bombay.

Solution of Lane–Emden type equations using Legendre operational matrix of differentiation

Abstract: In the present paper, an efficient numerical method is developed for solving linear and nonlinear Lane–Emden type equations using Legendre operational matrix of differentiation. The proposed approach is different from other numerical techniques as it is based on differentiation matrix of Legendre polynomial. Some illustrative examples are given to demonstrate the efficiency and validity of the algorithm.

A characteristics-based implicit finite-difference scheme for the analysis of instability in water cooled reactors

Abstract: The objective of the paper is to analyze the thermally induced density wave oscillations in water cooled boiling water reactors A transient thermal hydraulic model is developed with a characteristics-based implicit finite-difference scheme to solve the nonlinear mass, momentum and energy conservation equations in a time-domain A two-phase flow was simulated with a one-dimensional homogeneous equilibrium model The model treats the boundary conditions naturally and takes into account the compressibility effect of the two-phase flow The axial variation of the heat flux profile can also be handled with the model Unlike the method of characteristics analysis, the present numerical model is computationally inexpensive in terms of time and works in a Eulerian coordinate system without the loss of accuracy The model was validated against available benchmarks The model was extended for the purpose of studying the flow-induced density wave oscillations in forced circulation and natural circulation boiling water reactors Various parametric studies were undertaken to evaluate the model's performance under different operating conditions Marginal stability boundaries were drawn for type-I and type-II instabilities in a dimensionless parameter space The significance of adiabatic riser sections in different boiling reactors was analyzed in detail The effect of the axial heat flux profile was also investigated for different boiling reactors

Analysis of parallel channel instabilities in the CANDU supercritical water reactor

Abstract: The present work investigates the parallel channel density wave instability in the CANDU supercritical water reactor (SCWR) using a 1-D thermal-hydraulic model in the time domain. The model, which was used to analyze a single channel in-phase mode of instability in the SCWR, is extended for parallel channels in the reactor core to determine both in-phase and out-of-phase modes of oscillations considering the origination of the instabilities purely due to the thermal-hydraulic feedbacks without taking into account the influence of neutronic reactivity feedback effects. The capability of the proposed model to analyze the parallel channel instability is validated against the available experimental data. Extensive numerical investigations are carried out to determine the marginal stability boundary for each of the modes of oscillations in the working regime of the CANDU SCWR. The effect of the asymmetric heating power on the instability thresholds is also studied. Finally, the relative dominance between the in-phase and out-of-phase modes of oscillations at the operating regime of the CANDU SCWR is determined.

Numerical models to predict steady and unsteady thermal-hydraulic behaviour of supercritical water flow in circular tubes

Abstract: The present paper is aimed at the development of numerical models to predict steady and unsteady thermal-hydraulic behaviour of supercritical water flow at various operating conditions. A simple one-dimensional numerical thermal-hydraulic model based on a finite-difference scheme has been developed. A detailed CFD analysis based on two turbulence models, Reynolds Stress Model and k–ω SST model, has also been presented in this paper. Seven experimental cases of steady state and vertically up flowing supercritical water in circular tubes operated at various working regimes, such as normal and deteriorated heat transfer regions, are used to validate the numerical models. Comparisons for steady state flow show good agreement between the numerical and experimental results for all normal heat transfer cases and most of the deteriorated heat transfer cases. Next, the numerical models are used for transient simulations. Three case studies are undertaken with a purpose to quantify the time dependent responses from both the 1-D model and CFD model. The comparisons carried out for both the normal and deteriorated heat transfer conditions show a good agreement between the two numerical models.

Analysis of flow induced density wave oscillations in the CANDU supercritical water reactor

Abstract: In this paper, a 1-D thermal-hydraulic model, THRUST, is developed to simulate and analyze the CANDU supercritical water reactor (SCWR) from the thermodynamic point of view without considering the effect of neutronic coupling. THRUST, where a characteristic-based finite difference scheme is used, is validated against the available numerical results. The model is, then, used for the analysis of the CANDU SCWR with a primary focus to determine the conditions for potential density wave oscillations. Extensive numerical studies are performed to obtain the marginal stability boundary in the operating regime of the reactor. The effect of various parameters, such as mass flow rate, operating pressure, axial heat flux profile, local pressure drop coefficient, and friction factor, on the stability thresholds of the reactor have been investigated.

Neural network methods to solve the Lane–Emden type equations arising in thermodynamic studies of the spherical gas cloud model

Abstract: In the present study, stochastic numerical computing approach is developed by applying artificial neural networks (ANNs) to compute the solution of Lane–Emden type boundary value problems arising in thermodynamic studies of the spherical gas cloud model. ANNs are used in an unsupervised manner to construct the energy function of the system model. Strength of efficient local optimization procedures based on active-set (AS), interior-point (IP) and sequential quadratic programming (SQP) algorithms is used to optimize the energy functions. The performance of all three design methodologies ANN-AS, ANN-IP and ANN-SQP is evaluated on different nonlinear singular systems. The effectiveness of the proposed schemes in terms of accuracy and convergence is established from the results of statistical indicators.

Second kind Chebyshev operational matrix algorithm for solving differential equations of Lane-Emden type

Abstract: In this paper, we present a new second kind Chebyshev (S2KC) operational matrix of derivatives. With the aid of S2KC, an algorithm is described to obtain numerical solutions of a class of linear and nonlinear Lane–Emden type singular initial value problems (IVPs). The idea of obtaining such solutions is essentially based on reducing the differential equation with its initial conditions to a system of algebraic equations. Two illustrative examples concern relevant physical problems (the Lane–Emden equations of the first and second kind) are discussed to demonstrate the validity and applicability of the suggested algorithm. Numerical results obtained are comparing favorably with the analytical known solutions.

A review on recent heat transfer studies to supercritical pressure water in channels

Abstract: Recent studies on heat transfer to super-critical water (SCW) in tubes, annuli and rod bundles have been reviewed in support of the development of supercritical water-cooled reactors. Experimental investigations are primarily focused on the heat transfer deterioration (HTD) to examine its general behaviors, transition boundary and physical mechanisms. Large amount of experimental data were obtained from the experiments supplementing the extensive database previously compiled for fossil fuel-fired power plants. Prediction methods for heat-transfer coefficient were developed from various databases. These methods provide reasonable predictions at normal and enhanced heat-transfer regions, but fail to capture HTD. The upstream effects have not been considered in the prediction methods and may have an impact on local heat transfer, particularly in a channel with a non-uniform axial power profile or with flow or pressure transients. Most numerical studies evaluated the applicability of turbulence models to SCW using the computational fluid dynamics tools. Significant challenges remain in establishing the reliability of the turbulence models and the modeling of buoyancy and turbulent heat flux. Direct numerical simulation and large eddy simulation have been applied in understanding the HTD phenomena. These studies are limited to simple channels over a short axial distance at relatively low Reynolds numbers.