The Julia package LCMsim was developed to verify if the equations for compressible fluid flow through a thin curved cavity can be solved on a shell mesh. Although directly accessible as open source, the code was hard to understand, maintain and extend for outsiders. In this paper the general design of LCMsim after a refactoring step is discussed and general design principles for a numerical tool solving the equations of hydrodynamics are presented and implemented. LCMsim is designed to run mold filling simulations for Liquid Composite Molding, a manufacturing process for fiber reinforced polymer composites where dry fibers are placed into a mold which is subsequently closed or sealed with a flexible bag by drawing a vacuum. Afterwards, the pressure difference between the injection gates and the vents pushes the resin through the porous preform. The governing equations are specified as Initial-Boundary-Value problem with partial differential equations including temporal and spatial derivatives. Consequently, this paper can serve as a guidance for scientific computing applications. The results section quantifies the decrease in computational time for a benchmark problem after refactoring (17 times faster). In addition, a methodology is addressed for modifying existing equations as well as for adding supplementary equations of phenomenological models.