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Eulerian wall film (Mass convergence stabilized, film transport height varies!)

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Old   February 11, 2016, 21:37
Default Eulerian wall film (Mass convergence stabilized, film transport height varies!)
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Dear all,

Basically I am simulation an impinging orifice spray (jet) that creates particles. These particle undergone primary atomization due to internal nozzle state(eg diam, presssure, flow rate etc).

Secondly, this jet/spray is subject to cross-flow of up to 82 m/s.

As my solution has reach steady state where the particle had filled the domain and the mass convergence has not change radially with respect to time except for fluctuating from a mean value.

The film thickness is really intriguing me, at different time 0 s (zero height), 0.02 s example and 0.04 s are both very different. It makes sense to me that the waviness is due to film transport. However it does not make sense is that why isn''t the film profile reaches a steady state profile too? if both mass in and mass flow out is balanced (Unchanged in flow field due to coupling).

As I tried to simulate my flow using larger timestep Courant = 9 as the flow field almost remain unchanged.
Meanwhile my particle tracking is maintain at low timestep to ensure that they did not travel through domain too quickly as such affect the coupling with continuum.

Meanwhile, I also managed to keep the film courant number (<0.2 for stability) And I believe the film transport of CFL = 0.2 means that it travels 0.2 times of one cell.

If the film CFL is kept even lower I am afraid the changes will be even smaller. The thing puzzle me is the waviness that is not steady at all.

Does anyone has experience deal with this?

Thanks

Sincerely,
Jee L
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