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SUMMARYFlow through porous media has been used to model resin impregnation in composites manufacturing processes such as resin transfer molding. Many numerical schemes have been used to explore the e ciency and accuracy in description of the movement of the liquid front when it is introduced through injection gates into a mold containing stationary and compacted ÿbrous porous media. In all numerical schemes, injection gates are modelled with a single node. Mathematically, a single node deÿnition for a ÿnite radius injection gate imparts a singularity. In this paper, an approach to avoid this singularity by modelling the injection gate with more than one node is presented. An analytical solution relating the ÿll time to the injection gate radius is developed for a constant pressure injection from a spherical injection gate into an isotropic media. A new parameter 'mesh density level', deÿned as the ratio of the injection radius to the element size, is used to investigate the accuracy and the convergence of the numerical results. It is shown that the numerical results converge when the mesh density level is increased. The accuracy of the results depends on the ratio of the ow-front radius to the injection gate radius as well as on the mesh density level. In many situations, a spherical injection gate may not represent the correct physics and model simpliÿcation may be necessary.The impact of such simpliÿcations is also quantiÿed. The systematic analysis presented in this paper should prove useful to the modeller in taking the decision whether to select the proper, geometric deÿnition for the injection gate to obtain accurate results or to deÿne the injection gate using a single node and be aware of the errors introduced due to the singularity.

Analytical formulations for the pressure profile in rectilinear and radial flow vacuum infusion (VI) processes are developed. The coupled pressure formulations are solved using an iterative numerical procedure. As the formulations are coupled, reinforcement specific solutions need to be derived. The VI process is also modelled using a numerical flow simulation tool, using a previously reported approach. In addition, analytical formulations for fill times in the rectilinear and radial flow VI processes are developed. It is found that with increasing reinforcement compliance, the analytical VI pressure profile diverges from the resin transfer moulding (RTM) pressure profile. Results from numerical flow simulations show a similar behaviour. The error level in the numerical results of VI pressure solution depends on the reinforcement compliance. The fill times ratio, between equivalent RTM and VI processes, remains constant for rectilinear and radial flow processes. This allows one to use RTM flow simulation tools to model rectilinear and radial flow VI processes without any major modifications.Keywords: Liquid composite moulding u x flow velocity in the rectilinear direction, i.e. x direction, m s 21 v f fibre volume fraction v f0 , B curve fitting parameters for reinforcement compliance behaviour a non-dimensional distance (5x/L for rectilinear flow; 5(r2r inj )/(R2r inj ) for radial flow) m resin viscosity, Pa s r fibre density, kg m 23 w reinforcement porosity (512v f )

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