Aims We analyse mesogranular flow patterns in a three-dimensional hydrodynamical simulation of solar surface convection in order to determine its characteristics. Methods We calculate divergence maps from horizontal velocities obtained with the local correlation tracking (LCT) method. Mesogranules are identified as patches of positive velocity divergence. We track the mesogranules to obtain their size and lifetime distributions. We vary the analysis parameters to verify if the pattern has characteristic scales. Results The characteristics of the resulting flow patterns depend on the averaging time and length used in the analysis. Conclusions We conclude that the mesogranular patterns do not exhibit intrinsic length and time scales.