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Research paper thumbnail of A New Interpretation of Configurational Forces

Journal of Elasticity, 2011

In a recent paper [7] we interpreted configurational forces as necessary and sufficient dissipati... more In a recent paper [7] we interpreted configurational forces as necessary and sufficient dissipative mechanisms such that the corresponding Euler-Lagrange equations are satisfied. We now extend this argument for a dynamic elastic medium, and show that the energy flux obtained from the dynamic J integral ensures that the equations of motion hold throughout the body.

Research paper thumbnail of Krylov sub-space methods for K-eigenvalue problem in 3-D neutron transport

Annals of Nuclear Energy, 2004

Abstract The K -eigenvalue problem in nuclear reactor physics is often formulated in the framewor... more Abstract The K -eigenvalue problem in nuclear reactor physics is often formulated in the framework of Neutron Transport Theory. The fundamental mode solution of this problem is usually obtained by the power iteration method. Here, we are concerned with the use of a Krylov sub-space method, called ORTHOMIN(1), to obtain a more efficient solution of the K -eigenvalue problem. A Matrix-free approach is proposed which can be easily implemented by using a transport code which can perform fixed source calculations. The power iteration and ORTHOMIN(1) schemes are compared for two realistic 3-D multi-group cases with isotropic scattering: an LWR benchmark and a heavy water reactor problem. In both the schemes, within-group iterations over self-scattering source are required as intermediate procedures. These iterations are also accelerated using another Krylov method called conjugate gradient method. The overall work is based on the use of Sn-method and finite-differencing for discretisation of transport equation.

Research paper thumbnail of A simple scheme for the direct evaluation of time-eigenvalues of neutron transport equation

Annals of Nuclear Energy, 2003

A simple numerical scheme is presented for the evaluation of fundamental and higher discrete time... more A simple numerical scheme is presented for the evaluation of fundamental and higher discrete time-eigenvalues of neutron transport equation. It is based on the direct solution of a matrix equation obtained by discretisation of integro-differential form of the transport equation by using the S n-method with Diamond Difference scheme. The scheme is applied to mono-energetic homogeneous slab cases with isotropic scattering and verified against published accurate semi-analytical results. Although less accurate than the semi-analytical method, the scheme is more versatile. It is shown to be applicable to spatially heterogeneous cases also.

Research paper thumbnail of A New Interpretation of Configurational Forces

Journal of Elasticity, 2011

In a recent paper [7] we interpreted configurational forces as necessary and sufficient dissipati... more In a recent paper [7] we interpreted configurational forces as necessary and sufficient dissipative mechanisms such that the corresponding Euler-Lagrange equations are satisfied. We now extend this argument for a dynamic elastic medium, and show that the energy flux obtained from the dynamic J integral ensures that the equations of motion hold throughout the body.

Research paper thumbnail of Krylov sub-space methods for K-eigenvalue problem in 3-D neutron transport

Annals of Nuclear Energy, 2004

Abstract The K -eigenvalue problem in nuclear reactor physics is often formulated in the framewor... more Abstract The K -eigenvalue problem in nuclear reactor physics is often formulated in the framework of Neutron Transport Theory. The fundamental mode solution of this problem is usually obtained by the power iteration method. Here, we are concerned with the use of a Krylov sub-space method, called ORTHOMIN(1), to obtain a more efficient solution of the K -eigenvalue problem. A Matrix-free approach is proposed which can be easily implemented by using a transport code which can perform fixed source calculations. The power iteration and ORTHOMIN(1) schemes are compared for two realistic 3-D multi-group cases with isotropic scattering: an LWR benchmark and a heavy water reactor problem. In both the schemes, within-group iterations over self-scattering source are required as intermediate procedures. These iterations are also accelerated using another Krylov method called conjugate gradient method. The overall work is based on the use of Sn-method and finite-differencing for discretisation of transport equation.

Research paper thumbnail of A simple scheme for the direct evaluation of time-eigenvalues of neutron transport equation

Annals of Nuclear Energy, 2003

A simple numerical scheme is presented for the evaluation of fundamental and higher discrete time... more A simple numerical scheme is presented for the evaluation of fundamental and higher discrete time-eigenvalues of neutron transport equation. It is based on the direct solution of a matrix equation obtained by discretisation of integro-differential form of the transport equation by using the S n-method with Diamond Difference scheme. The scheme is applied to mono-energetic homogeneous slab cases with isotropic scattering and verified against published accurate semi-analytical results. Although less accurate than the semi-analytical method, the scheme is more versatile. It is shown to be applicable to spatially heterogeneous cases also.

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