This presentation discusses a model to simulate the behavior of particle-laden slurry in a horizontal perforated wellbore with the goal of quantifying particle distribution between perforations. There are two primary phenomena that influence the result. The first one is the non-uniform particle distribution within the wellbore’s cross-section and how it changes along the flow. The second phenomenon is related to the ability of particles to turn from the wellbore to a perforation. Mathematical model for each sub-problem is developed and calibrated independently against available data. Results of simulations for the multi-cluster geometry also agree well with the available laboratory and field scale experiments. The importance of the developed model can be summarized as follows. First of all, it allows to better understand the physical processes occurring in the wellbore, which in turn helps understanding sensitivities to problem parameters. Then, the model can be used to create perforation designs leading to nearly uniform proppant distribution between clusters. Finally, it can be (and will be) integrated into ResFrac to investigate the overall effect of the aforementioned non-uniform proppant distribution on the overall treatment efficiency.