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February 26, 2020 at 11:34 pmsolovievSubscriber
Hello,
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I am working on implementing a new simulation to model evaporation and heat at the air-sea interface under strong winds. I have looked at tutorials and the user's guide and have come up with some starting parameters.Â
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I was hoping I could verify that these would be sufficient before trying the model.
gravity on
should energy equation be checked? I don't believe it's necessary here
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Models:
Multiphase - Eulerian - should either Multi-fluid VOF or Dens discrete phase model be applied as well?
Implicit formulation
Phase interaction: mass transfer - evaporationÂ
surface tension - set constant
heat transfer - 2 resistance modelÂ
Viscous model - k- omega SST (dispersed?)
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Species transport model - does this need to be enabled with a moist air material for effective evaporation?
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Materials:
water, air, moist air? (mix of air/water)
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Boundary conditions:
no slip on most boundaries, except wind applied either at inlet or at top of domain.Â
would consider applying periodic boundaries if I run this model with waves eventually.Â
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Solution methods: These I am not so certain ofÂ
Scheme: Phase coupled simple
Gradient: Least squares cell based
Pressure: Presto!
Momentum: First order upwind
Volume fraction: geo reconstruct
Transient formulation: bounded second order
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I plan to patch the water in (no waves initially).
I read on another forum that the evaporation needs to be driven by the relative humidity, I want to ensure this is done properly.Â
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I would appreciate any assistance in developing this model properly!
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Thanks,
Alex -
February 27, 2020 at 5:36 amDrAmineAnsys EmployeeYou need two phases where the gas phase is wet air mixture. Better to use a bit more diffusive scheme at the interface like compressive. For mass transfer use UDF or species mass transfer. For turbulence stick to mixture turbulence first.
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February 27, 2020 at 5:37 amDrAmineAnsys EmployeeInterfacial area to be set as gradient or user defined.
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February 27, 2020 at 2:39 pmsolovievSubscriber
Sounds great. I will run a trial with these settings and let you know if I have any problems or questions.
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Thanks,
Alex -
February 27, 2020 at 3:55 pmDrAmineAnsys Employee
Better to use UDF for mass transfer and rely on Schrage's law for mass transfer
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February 27, 2020 at 7:37 pmsolovievSubscriber
Question, should the energy equation be checked?
Other question, would either dense discrete phase model or multi-fluid vof model be applicable here in eulerian parameters?Â
Thanks,
Alex
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February 28, 2020 at 6:25 amDrAmineAnsys Employee
If this is only due to concentration gradients then you can switch it off but you will then not account for any energy content change due to vaporization..
Why DDPM?Â
MultiVOF is a submodel allowing for better interlolation schemes. So you can use it, bear in mind that the interface mass transport would rather require something diffusive use ndo not use at first GEo. (Compressive from Sharp/Dispersed is fai enough.)
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February 28, 2020 at 10:58 pmsolovievSubscriber
Thank you. I have implemented these settings. I will work on a UDF for mass transfer as well. I am only familiar with editing UDFs, I have not written one from scratch yet.
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Thanks,
Alex
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March 5, 2020 at 10:57 pmsolovievSubscriber
Hello,
We have been further working on this model. Is there a way to use the LES viscous model with the eulerian multiphase model? We switched to the eulerian model to implement the heat transfer in the phase interactions tab, but LES is crucial to our simulations. I see that the mixture model is compatible with LES, would this multiphase model be appropraiate for our situation?Â
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Thanks,
Alex
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March 16, 2020 at 8:04 pmsolovievSubscriber
Hello,
I was wondering if there are any answers to my questions above?Â
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Thanks,
Alex
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March 17, 2020 at 6:46 amDrAmineAnsys Employee
The LES turbulence model is only available as beta feature.
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March 17, 2020 at 9:17 pmsolovievSubscriber
So it can be used with the Eulerian model if the beta feature is turned on?
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Thanks,
Alex
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March 18, 2020 at 8:12 amDrAmineAnsys Employee
Yes.
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- The topic ‘Eulerian model for evaporation and heat exchange’ is closed to new replies.
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