Monitor of max velocity is const but keep on increasing in avg velocity.

PratikJ · May 17, 2023, 02:21

Hello all,
So my brief case set-up:
Steady-state, Multiphase (Air and liquid) (VOF model), Realizable k-e turbulence model.
Three monitors: Mass-flow rate at outlet, Avg velocity magnitude in liquid domain, Max velocity magnitude in liquid domain

So, before jumping into directly transient simulations I am running steady-state simulations first. After 9500 iterations, what I had observed is that monitor of max velocity magnitude is almost constant but profile of volume avg velocity is keep on increasing.
Interestingly enough, even residuals are now in order of 10^(-3).
What does this result signify?

From what I understand is that it is because turbulent eddies generated within domain as simulation progresses.

In such case, what would be the right time to stop steady-state simulation ? or should I revisit the case set-up and change the turbulence model.

PratikJ · May 17, 2023, 23:22

Max velocity monitor plot :
https://drive.google.com/file/d/1ZI8...usp=share_link

Avg velocity monitor plot :
https://drive.google.com/file/d/115-...usp=share_link

May 17, 2023, 02:21	Monitor of 'max velocity' is const but keep on increasing in case of 'avg velocity'.	#1
PratikJ New Member Zoro_07 Join Date: Oct 2021 Posts: 3 Rep Power: 4	Hello all, So my brief case set-up: Steady-state, Multiphase (Air and liquid) (VOF model), Realizable k-e turbulence model. Three monitors: Mass-flow rate at outlet, Avg velocity magnitude in liquid domain, Max velocity magnitude in liquid domain So, before jumping into directly transient simulations I am running steady-state simulations first. After 9500 iterations, what I had observed is that monitor of max velocity magnitude is almost constant but profile of volume avg velocity is keep on increasing. Interestingly enough, even residuals are now in order of 10^(-3). What does this result signify? From what I understand is that it is because turbulent eddies generated within domain as simulation progresses. In such case, what would be the right time to stop steady-state simulation ? or should I revisit the case set-up and change the turbulence model. Last edited by PratikJ; May 17, 2023 at 23:25.

May 17, 2023, 23:22	Adding plots for reference	#2
PratikJ New Member Zoro_07 Join Date: Oct 2021 Posts: 3 Rep Power: 4	Max velocity monitor plot : https://drive.google.com/file/d/1ZI8...usp=share_link Avg velocity monitor plot : https://drive.google.com/file/d/115-...usp=share_link

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