This work presents one of the first CFD studies carried out to understand the fouling of exhaust gas recirculator (EGR) cooler surfaces. The deposition of soot particles in wavy-fin EGR coolers is studied by way of simulations carried out in a periodic framework. In the presence of very high temperature gradients, usually prevalent in EGR flows, the particle deposition process is dominated by the thermophoretic force. Calculations are performed for 10 and 100 nm particles at various Reynolds numbers and wall temperature gradients ranging from 1.0 to 9.45 x 10(6) Kim. It is seen that for the sub-micron particle sizes considered, the deposition process is independent of the particle size. Simulations in the wavy-fin geometry indicate the presence of preferential deposition patterns, corresponding to the regions of higher heat transfer. At lower Reynolds numbers, the amount of deposition increases considerably due to the higher particle residence times. Also, the amount of deposition exhibits a linear relationship with the applied wall temperature gradient, thus confirming the importance of thermophoresis in the soot deposition process. (C) 2010 Elsevier Ltd. All rights reserved.