Internal flow is a very general category which describes the flow of a fluid that is contained by and passes through a solid structure. There may be one or several openings through which fluid enters and leaves the device. The solutions to internal flow problems are among the most difficult to achieve in “typical” CFD, particularly for turbulent and compressible flows with complex geometry. This is because there are often multiple flow regimes throughout different regions of the device, with widely varying mathematical characteristics throughout the calculation domain.
Autodesk® CFD has several tools to aid convergence for a wide range of internal flow problems. These tools include the Automatic Turbulent Start-Up algorithm, Auto-Convergence Control, and Auto-Stop. These algorithms work to prevent solution instability or divergence, particularly in the early iterations.
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