Due to the presence of a high voltage and the specific geometry configuration, corona discharge is an inevitable part of many electrostatic coating processes. A full mathematical model of the corona discharge is practically impossible to implement due to the complexity of the problem. In this article, a new, simplified, and efficient method for incorporation of the corona current into the numerical model of the electrostatic coating process is presented. The objective of this article is to describe the novel procedure and fit it into the existing numerical frameworks. A software package Fluent is used to solve a transport equation for a new, user-defined scalar function. The gradient of this function corresponds to the corona current density. The numerical simulation is performed for the full 3D model of the problem and the sample results of the simulations are presented.