Approximation and reconstruction of the electrostatic field in wire-plate precipitators by a low-order model

The numerical computation of the ionic space charge and electric field produced by corona discharge in a wire-plate electrostatic precipitator (ESP) is considered. The electrostatic problem is defined by a reduced set of the Max well equations. Since self-consistent conditions at the wire and at the plate cannot be specified a priori, a time consuming iterative numerical procedure is required. The efficiency of ail numerical solvers of the reduced Maxwell equations depends in particular on the accuracy of the initial guess solution. The objectives of this work are two: first. we propose a semianalytical technique based on the Karhunen-Loeve (KL) decomposition of the current density held J. which can significantly improve the performance of a numerical solver; second, we devise a procedure to reconstruct the complete electric field from a given J. The approximate solution of the current density field is based on the derivation of an analytical approximation J. which. added to a linear combination of tiw KL basis functions, constitutes an accurate approximation of J. Tn the first place, this result is useful for optimization procedures of the current density field, which involve the computation of many different configurations. Second, we show that from the current density field we can obtain an accurate estimate for the complete electrostatic held which can be used to spaed up the convergence of the iterative procedure of standard numerical solvers, (C) 2001 Academic Press.