User errors result from the inadequate use of the resources available for a CFD simulation. The resources are given by:
Problem description
Computing power
CFD software
Physical models in the software
Project time frame.
According to the ERCOFTAC Best Practice Guidelines [140], some of the sources for user errors are:
Lack of experience
Lack of attention to detail or other mistakes.
Often, user errors are related to management errors when insufficient resources are assigned to a project, or inexperienced users are given a too complex application. Typical user errors are:
Oversimplification of a given problem; for example, geometry, equation system, and so on
Poor geometry and grid generation
Use of incorrect boundary conditions
Selection of non-optimal physical models
Incorrect or inadequate solver parameters; for example, timestep, and so on
Acceptance of non-converged solutions
Postprocessing errors.