Thanks a lot dear Dr. Hidouri for you the document

Kind Regards

Dear Dr. Ali, before answering, I considered that you are asked this question for purpose to identification of experimental side, as we know sometimes it becomes necessary to quantify the amplitude of oscillation as a certain percentage when looking for steady-state value. amplitudes more than minus/plus 10% of the mean value is often considered as steady-state (indication for stability). some researcher recommend minus/plus 30% is a cutoff value. the transition flow due to two-phase regimes cause increasing in stability of the system and there are different type of stability but I think both hydrodynamics and thermal control play major roles to control stability by controlling flow patterns via mass and heat fluxes. I think stability very important field in boiling two-phase of natural and forced circulation systems because design and safety operation of industrial application related with such type of boiling depend on it. regards

Dear Mohamed,

I'm thankful for your answer where I find it very interesting. I agree about the importance of the stability field in boiling two-phase flow. In addition many authors subdivided flow instability in three ways.

- pressure drop instability

- thermal instability

and wave oscillation instability

for each kind of instability have its characteristics and its causes thermal and/or hydrodynamic . however I think from my research in this subject that, in boiling flow, hydrodynamic effects are influenced by thermal effects

I find this conversation very interesting!

Especially the Historical Review provided by @Khaoula Hidouri is excellent.

I wonder if there is similar Hydrodinamic History on the gas-solid flow in fluidization for example?

You are welcome Dr. Stanislaw

Dear Ali

Respected, See the link:

https://www.uh.edu/engines/HydrodynamicHistory.pdf

All the best and happy