Injection moulding simulation involves solving the governing equations of mass, momentum, and energy numerically over the physical domain. The numerical implementation involves discretizing the physical domain into a number of sub-domains, or elements. The dependent variables (velocity, pressure, temperature) are approximated within each element. In short, the continuous domain is broken into many connected sub-domains and the dependent variables are approximated over the whole domain.

Mesh density is the number of elements per unit area. In general, the more elements in the mesh, the more accurate the analysis results, at the expense of longer calculation times.