I am currently doing validation for my Wells turbine. Before stall conditions, i am able to get convergence properly. However after stall, i.e at higher velocities my residuals and mass imbalances are not a straight line, instead they follow a repetitive sinusoidal pattern even after larger iterations.
In this case how to verify whether my simulation has converged or not ?. Please suggest.
The screenshots of mass imbalance, torque monitor and residuals are attached below.
Madhan Kumar,
The oscillatory behavior of the residuals emanates from the vortex shed that causes a continuous sinusoidal variation in pressure distribution in the trailing edge. Therefore, it is expected that the oscillations i residuals are steady and continuous.
However, in the absence of good residual convergence, more emphasis is placed on the global variables such as the forces. In this case, the solutions can be considered converged when the oscillations are within 2-5% of the mean value.
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