Effects of mesh refinement, time step size and numerical scheme on the computational modeling of temperature evolution during natural-convection heating

• Natural-convection heating in canning was done as time-dependent laminar solution.
• Effects of time step size and mesh refinement in this CFD study were demonstrated.
• Lowering time step size and refining mesh did not lead to any accuracy.
• Further mesh refinements might deteriorate the results.
• Results bring into the question of achieving better accuracy with finer mesh.

A computational fluid dynamics (CFD) analysis includes creating geometry, dividing it into elements, discretizing governing equations and solving with suitable numerical schemes. Refining mesh and lowering time step size increase accuracy. However, this may not always give the best result since convergence depends upon parameters of time step size, mesh resolution and numerical scheme. Therefore, the objective of this study was to determine the effects of these on the accuracy of a CFD solution. For this purpose, canning example was used, and results obtained with ANSYS CFX (v12.1.) were experimentally validated. Effects of time step size, mesh resolution and numerical scheme on temperature and velocity field evolution were determined. Mesh refinement affected temperature distribution significantly and surprisingly led to less accuracy. The reasons for this behavior were presented and explained comprehensively.