Abstract: An approach is carried out for solving twodimensional aeration in grain bins and an alternative formulation is derived in which stream function is used instead of pressure in the model founded by Brooker and Segerlind. As a result, natural boundary conditions along bin walls in the pressure model is reduced to a forced one which allows to specify stream function values on bin walls. The new model is validated through a numerical example (the case of 500 Pa inlet pressure) which was presented and computed by Brooker using a scheme with control volume formulation. Flow patterns of stream line and plot of isopressure lines are presented. Numerical comparison with the pressure model on pressure values at selected points shows good equivalence. The iteration practice shows the new model can greatly reduce CPU time to about 1/15 of the former model. The formulation is also suitable for use of the finite element method.