An approximate method for oxygen diffusion in a sphere with simultaneous absorption

The oxygen diffusion problem is usually formulated in two stages. first, the steady state and second, the moving boundary stage. In this paper, we will consider the solution of the second stage in which a new semi-analytical method for solving such a problem was developed. The present method starts by assuming a polynomial representing the profile of oxygen concentration, and then by some mathematical manipulation a system of linear equations is obtained. Numerical solution for the system with a simple scheme relating the moving boundary and its velocity leads to the unknown functions in the assumed polynomial.