Inconsistent dtM and CFL values in the log file

[windseacn]

From the online manual, I learned how to evaluate the time step to ensure model stability. However, I observed that the CFL number in the log file is consistently about half of what I estimated using the methods described in the manual. Upon reviewing the source code, I discovered that the initialization of the k value differs from the procedure outlined in the manual.

source code:
NatFreqCFL::stiffness(EA * N / UnstrLen);

manual:
$k=4 EA \frac{N}{L}$

[sanguinariojoe]

Yeah, I remember I discussed this at some point. There is indeed a 4 factor, and probably we can add it to the CFL... We just kept the order of magnitude for simplicity.

Opinions @RyanDavies19 ?

[RyanDavies19]

I would say it's good to add, as that is from @mattEhall's notes on the original MoorDyn v1. I believe the factor of 4 comes from 2x segments providing damping at the node, and a 2x relative velocity at the node (because of the out-of-phase assumption).