This happen always on my installations with SW2014. How it is with you? - Is it the same with SW2015 and SW2016?
If I close SW Session the control of the Flow Simulation Solver Monitor is lost and if the runs do not converge it cannot be stopped normally. The parameters of the Flow Simulation remain without control. This happened since SW2013 when the Solver thread was separated from the Solid Works Session thread. However it seems, that this separation is not done in the best way if we cannot control the solver parameters, as well as cannot save the results prior the initially set convergence is met.