[oliveira1820]

If I want to study, let´s say, the difference between simulations where I only change the cooling water flow: e.g.

First simulation --- inital water flow = 2 kg/s------begins at 0 seconds------calculate-----first solution


Second simulation ----- flow = 3kg/s --- begin with file of soution from first simulation--- calculate ------ second solution



Can I use the converged solution of a previous value to speed up simulation and yet get the same solution as if I had started from 0? Or it will be different from calculating the solution from 0 seconds with the new flow value?

[ghorrocks]

Yes, you can use the flow at a different flow rate as an initial condition. Usually it will converge to the same flow as if it had run from a zero flow initial condition, but it it quite possible that the different initial conditions will lead to different converged solutions. This is an inherent property of fluid flow, it is sensitive to initial conditions and can bifurcate to multiple metastable states.

An example of this includes the Coanda effect - if the jet starts stuck to the wall it will stay there, but if the jet starts away from the wall it will stay away from the wall. This is an example of a flow which can bifurcate to multiple metastable results.

This is one reason why fluid flow is so interesting.