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In Time Domain simulation, I was wondering the exact use of the "skip Initial" function.

I'm just a user so I'm not 100% sure, but it seems from my experience that if you "Skip Initial" it skips an initial DC analysis, which can impact things like charges on capacitors and such. But, I would like to hear from an authority on this subject.

Although very few details of it's operation are made public, CL seems to operate in a similar way to SPICE. Hence paragraph 1.1.1 of this:

http://newton.ex.ac.uk/teaching/cdhw/Electronics2/userguide/sec1.html#1.1.1

might be of some help.

Essentially, if the "skip Initial" function is ticked then no .op analysis is carried out.

This can lead to some wild results particularly with models such as the CL rail-less opamp which has no contraints on the output voltage.

It may help in some poorly converging sims but it is often better to find some way to force your own initial conditions anyway. SPICE has various ways to do this but CL does not have any built-in options. To see some workarounds for this, search CL for:

initial conditions

start up

Indeed, sometimes you need to 'Skip initial' (no .op analysis) if you're using op-amps. For instance, when making a Wien bridge oscillator (sine wave).