[Zhudasch]

Hi everyone. I'm now busy with simulating the cooling of an exhaust System in vehicle. Here is how the whole Simulation goes:

1. The whole exhaust system will be at first heated with hot air (700C) until the temperature doesn't Change any more. That's to say, this period can be done by using steady state solver.
2. Then the hot air won't be sent into the exhaust system anymore. Starting from this Moment the exhaust system will be cooled off by nature convection. The cooling lasts for 20min. What I focus on is the changing of temperature in this period.

Obviously I can set up the whole model in 1 sim-file and let the fluid and solid domain be solved transiently at the same time. Alternatively, I can do a co-simulation, since the fluid domain needs a much shorter time-step. I haven't tested the simulation in both configurations. But I think it doesn't make much difference in the simulation time.

Here is the question: I was suggested that the fluid domain can be run in quasi-stationary mode while the solid in transient solver. It seems that the computation time in fluid domain can be largely reduced. But I find out that the steady solver can generate the temporary solution that don't happen in real life. So for very large time-step the results in fluid Domain can be really uncorrect. I doubt about this idea. But can anyone tell me whether it's possible to do so?