Techniques for evaluating a fluid flow through a wellbore include identifying an input characterizing a fluid flow through a wellbore; identifying an input characterizing a geometry of the wellbore; generating a model of the wellbore based on the inputs characterizing the fluid flow and the geometry of the wellbore; simulating the fluid flow through the wellbore based on evaluating the model with a numerical method that determines fluid flow conditions at a first boundary location uphole and adjacent to a perforation of a plurality of perforations in the wellbore and at a second boundary location downhole and adjacent to the perforation; and preparing, based on the fluid flow conditions determined with the numerical method, an output associated with the simulated fluid flow through the wellbore for display to a user.