Steady-state flow is the condition where the fluid properties at any single point in the system do not change over time. In many systems, it requires some time after the system initiates before the fluid properties stabilize (and become independent of time). This time period is referred to as the transient state, which is characterized by unsteady flow. Typical flow properties you may evaluate during steady flow conditions include pressure, momentum, energy, and temperature. There are many examples of steady flow conditions that demonstrate the importance of steady-state flow simulations. The continuous flow of a river is an example of steady-state flow. In this scenario, you may want to simulate the effects of the river's flow on a dam located downstream. Additional examples include:
When you define a steady-state flow step for your simulation, your simulation results consist of fluid properties evaluated using steady flow. Results are not provided for the transient state. You can define controls that apply to the entire steady-state flow step to improve the speed and accuracy of the analysis. These controls include defining the maximum number of iterations, the stopping criteria, and the under-relaxation factor. You can also fine-tune the various equation solvers required for your scenario to adjust each solver's behavior in more specific ways. | ||||||