Numerical simulation in 3 steps
Definition of the domain and geometry to study. Creation of a spatial discretization: the different volumes of the domain are divided into several thousands/million elementary volumes (cells). Definition of initial conditions as well as physical models.
In the end, surely the most important and heavy step in numerical simulation engineering.
Namely : Many software packages offer automatic CAD repair and mesh generation processes. This reduces the time spent by the engineer. However, this can also lead to a reduction in the quality of the results, or even to incorrect results.
This is the actual step of the numerical calculation. It consists of the execution of a computer program for the numerical resolution of the preservation equations by an iterative method using a numerical discretization scheme.
The calculation can be performed in parallel, on a large number of cores in order to reduce the overall calculation time.
Each simulation code has more or less powerful parallelization algorithms, generally based on MPI (Messages Parsing Interface) libraries.
Namely : The increase in performance is not infinitely proportional to the number of cores. Thus, the number of cores is adapted according to the performance layer of the simulation code (or scalability curve).
This step makes it possible to visualize the results, to analyze them and to interpret the physics resulting from the calculations thanks to visualizations, sections or animations.
The visualization allows the interpretation of physical fields such as :
- Pressure, Velocity, Temperature, Turbulence
- Species concentration, Chemical reactions
- Noise sources
Namely : The interpretation of the results requires mastery of the analysis software but above all skills in physics and knowledge of the product analyzed