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## Increasing Time Steps

Reduces Iterations?

**
At the suggestion of Art Taylor of Old Dominion University, we
increased the time steps by factors of 2, 4, and 8. In all cases,
the answer converged to the correct AD value. The figure below shows
the derivative of coefficient of lift with respect to angle of attack for
each of these four timesteps:
**

The number of iterations reduced by factors of 2, 4, and 4.
Apparently, increasing the time step by a factor of 8 does not
improve the convergence any more than a does a factor of 4. We
do not know if the CFL number can always be increased, but the
technique certainly bears further consideration.