The choice of appropriate inflow conditions is crucial for the stability and accuracy of flow simulations. These conditions are often used as initial values for the entire flow domain, which can, however, lead to significant disturbances during the first iterations or time steps and may even cause the solution to diverge. To avoid such issues, initially lower values or simplified physical models can be used to calculate the initial conditions. The resulting solution then serves as a starting point for the main simulation.
It is important to note that a certain number of time steps or iterations is required until a stable flow is established. This number correlates with the time it takes for a particle to traverse the entire computational domain. Depending on the method and system, a multiple of this traversal time may be necessary. For slow flows or large computational domains, the number of required time steps or iterations increases accordingly. These aspects must be carefully considered when planning and conducting flow simulations to achieve reliable and physically meaningful results.