CFD Online Discussion Forums - Reverting from the currently performed iteration

Dear experts!

Is there any option to revert computation from current iteration (timestep)?

I speak about transient simulations.
This problem occurs when we use big timestep, the system generates sudden rare large heat source fluctuations. Energy is captured not accurately.

The idea is to recalculate last iteration (timestep) but with smaller timestep size.

The first solution idea was to use Adaptive Time Stepping and manipulate truncation error tolerance value. From Ansys Fluent User's Guide manual

Quote:

if the calculated truncation error is greater than the tolerance limit, we have the option of reverting from the currently performed iteration, which is moving from the N step to N+1 step, and performing the iteration with a smaller time step

While it works somehow, this approach turned out to be very unstable and inefficient.

Other solution idea was write data after each timestep, but it is very expensive in terms of computation time.

So once again, is there any option to recalculate current timestep with smaller timestep size?

best regards