Abstract
The stages of creating a three-dimensional computational domain and generating a grid model for CFD modeling of flow hydrodynamics in a pipe-in-pipe heat exchanger are considered in detail. The sequence of actions for grid generation in COMSOL multiphysics is described. A description is given of the method of thickening the grid by dissecting the volume with a surface and constructing grids with the required interval in each of the resulting connected volumes. A model grid with triangular and square elements was used for the heat exchange model. The construction and adjustment of the model grid plays an important role in multiphysical modeling. The accuracy of the final results depends on the correctness of the model grid setting. During modeling, it is necessary to pay attention to the size of the model grid, the quality and type of the grid.