Computational models are described which were built for parametric simulations of permanent magnet (PM) dipoles with a longitudinal field gradient. The dipoles will be used as bending magnets in the synchrotron facility SILA, a new project of the National Research Center “Kurchatov Institute”. The dipoles employ a Sm-Co permanent magnet material and pure iron. The need for high magnetic performance and anticipated interference between neighbouring components is a challenge for design and construction of the magnet system. For this reason the magnet designs must rely on precision 3D simulations. The dipoles are described in detail with parameterized models. Parametric simulations are to be applied at all stages of the project till the commissioning to provide realistic prediction of the magnet behaviour.