Abstract
Recently, we have developed a higher‐order and unconditionally stable compact finite difference scheme for solving a model of energy exchanges in an N‐carrier system with Neumann boundary conditions, which extends the concept of the well‐known parabolic two‐step model for microheat transfer. However, the combined compact finite difference scheme for the boundary is second‐order accurate. Unfortunately, our statement in (Dai and Tzou, Numer Methods Partial Differential Equation, Zhao et al., Numer Methods Partial Differential Equations 23 (2007), 949–959.), that it is a fourth‐order scheme is inaccurate, because the scheme was multiplied by Δ__x__^2^ in the derivation. In this article, we develop a new combined compact finite difference scheme for the boundary, which is third‐order accurate. Using the exact same proof for stability analysis as in (Dai and Tzou, Numer Methods Partial Differential Equations), the new scheme is unconditionally stable with respect to the initial conditions and source terms. The improved compact scheme is then tested by a numerical example. Results show that the convergence rate with respect to the spatial variable from the new scheme is higher and the solution is much more accurate, when compared with those obtained using our previous compact scheme in (Dai and Tzou, Numer Methods Partial Differential Equations). © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2011