Splashing Droplet in Spray-Wall Interaction

Crisu · January 21, 2021, 10:45

Hi Community,

I am modeling a spray-wall interaction where the spray hits a flat plate so that I can how many droplets be a wall film, how many are rebounding, and how many are splashing.

In "spray.in", there is the variable "rmsplash" (Fraction of parcel mass that is splashed when a parcel undergoes splashing.) and I am confused about it. What does it mean? Does this fraction tell me how much liquid mass remains on the surface as a wall film and how much liquid mass continues moving after splashing?

If so, how come I would need to define it beforehand, is it not depending on the E^2 and E^2_crit how much liquid would remain on the surface?

I would be very happy if someone could help me with this issue.
Thank you very much.
Christoph

ksrivast · January 22, 2021, 22:07

Hello Christoph,

When using the O'Rourke film splash model, CONVERGE uses either the E^2 or Weber(We) number criterion and the Rebound Weber number, specified in spray.in, to decide the outcome (rebound or film or splash) of each parcel-wall interaction. If a splash outcome is evaluated, users have the flexibility to specify the fraction of the impinging parcel's mass that will be used to create a new parcel. The rest of the mass will be incorporated into a wall film.

If you, however, have a relationship/equation to calculate splashed mass through the incoming parcel's E^2 or other properties, then you can easily incorporate it into a UDF approach, instead of using our default approach of having a fixed user-specified value for all parcels with a splash outcome.

Please refer to our manual for more details on the above. If you would like assistance with a UDF approach to individually calculate splash mass for each splashed parcel, please reach out to us at support@convergecfd.com. Please use your official email for all correspondence with Convergent Science. Please state your request, attach a case setup if possible and mention the cfd-online thread, as reference.

Sincerely,

Crisu · January 23, 2021, 04:32

Hello Kislaya,

Thank you very much for your reply. That's very helpful for me.

Christoph

January 21, 2021, 10:45	Splashing Droplet in Spray-Wall Interaction	#1
Crisu New Member Christoph Join Date: Jan 2021 Posts: 4 Rep Power: 5	Hi Community, I am modeling a spray-wall interaction where the spray hits a flat plate so that I can how many droplets be a wall film, how many are rebounding, and how many are splashing. In "spray.in", there is the variable "rmsplash" (Fraction of parcel mass that is splashed when a parcel undergoes splashing.) and I am confused about it. What does it mean? Does this fraction tell me how much liquid mass remains on the surface as a wall film and how much liquid mass continues moving after splashing? If so, how come I would need to define it beforehand, is it not depending on the E^2 and E^2_crit how much liquid would remain on the surface? I would be very happy if someone could help me with this issue. Thank you very much. Christoph

January 22, 2021, 22:07		#2
ksrivast Senior Member Kislaya Srivastava Join Date: Sep 2017 Location: Convergent Science, Northville MI Posts: 165 Rep Power: 8	Hello Christoph, When using the O'Rourke film splash model, CONVERGE uses either the E^2 or Weber(We) number criterion and the Rebound Weber number, specified in spray.in, to decide the outcome (rebound or film or splash) of each parcel-wall interaction. If a splash outcome is evaluated, users have the flexibility to specify the fraction of the impinging parcel's mass that will be used to create a new parcel. The rest of the mass will be incorporated into a wall film. If you, however, have a relationship/equation to calculate splashed mass through the incoming parcel's E^2 or other properties, then you can easily incorporate it into a UDF approach, instead of using our default approach of having a fixed user-specified value for all parcels with a splash outcome. Please refer to our manual for more details on the above. If you would like assistance with a UDF approach to individually calculate splash mass for each splashed parcel, please reach out to us at support@convergecfd.com. Please use your official email for all correspondence with Convergent Science. Please state your request, attach a case setup if possible and mention the cfd-online thread, as reference. Sincerely, __________________ Kislaya Srivastava Principal Research Engineer \| Applications CONVERGECFD

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January 23, 2021, 04:32		#3
Crisu New Member Christoph Join Date: Jan 2021 Posts: 4 Rep Power: 5	Hello Kislaya, Thank you very much for your reply. That's very helpful for me. Christoph