Narrow Results

A numerical analysis has been carried out to investigate the problem of magnetohydrodynamic (MHD) boundary-layer flow and heat transfer of a viscous incompressible fluid over a fixed plate. Convective surface boundary condition is taken into account for thermal boundary condition. A problem formulation is developed in the presence of thermal radiation, magnetic field and heat source/sink parameters. A similarity transformation is used to reduce the governing boundary-layer equations to couple higher-order nonlinear ordinary differential equations. These equations are numerically solved using Keller–Box method. The effect of the governing parameters such as radiation, Prandtl number, Hartman number, heat source/sink parameter on velocity and temperature profile is discussed and shown by plotting graphs. It is found that the temperature is an increasing function of convective parameter A, radiation and heat source parameters. Besides, the numerical results for the local skin friction coefficient and local Nusselt number are computed and presented in tabular form. Finally a comparison with a previously published results on a special case of the problem has done and shows excellent agreement.

Over the last few decades, developing efficient iterative methods for solving discretized partial differential equations (PDEs) has been a topic of intensive research. Though these efforts have yielded many mathematically optimal solvers, such as the multigrid method, the unfortunate reality is that multigrid methods have not been used much in practical applications. This marked gap between theory and practice is mainly due to the fragility of traditional multigrid methodology and the complexity of its implementation. This paper aims to develop theories and techniques that will narrow this gap. Specifically, its aim is to develop mathematically optimal solvers that are robust and easy to use for a variety of problems in practice. One central mathematical technique for reaching this goal is a general framework called the Fast Auxiliary Space Preconditioning (FASP) method. FASP methodology represents a class of methods that (1) transform a complicated system into a sequence of simpler systems by using auxiliary spaces and (2) produces an efficient and robust preconditioner (to be used with Krylov space methods such as CG and GMRes) in terms of efficient solvers for these simpler systems. By carefully making use of the special features of each problem, the FASP method can be efficiently applied to a large class of commonly used partial differential equations including equations of Poisson, diffusion-convection-reaction, linear elasticity, Stokes, Brinkman, Navier-Stokes, complex fluids models, and magnetohydrodynamics. This paper will give a summary of results that have been obtained mostly by the author and his collaborators on this topic in recent years.