The liquid fuel ramjet system employing a subsonic side-dump combustor is simulated in the present study, and the predictions are compared with the available experimental data. The complex combustion phenomenon in a ramjet combustor has been carried out using probability density function (PDF) approach. The complexity arises because of the mixing of fuel and air streams, and the burning of the resultant mixture, within the confined space of the combustion chamber. The predicted numerical results have been validated with the results available in open literature for a two-dimensional case and with in-house experimental data for a three-dimensional case. The methodology allows different designs to be evaluated quantitatively based on the performance metrics such as combustion efficiency, flame stability, etc. © 2008, DESIDOC.