Multi-hole Injector Cyclic Injection using VOF-Spray One-Way Coupling
 

Hi,

I am working on a multi nozzle spray modeling task using the VOF-Spray One-Way Coupling method in CONVERGE v3.0.

Since the VOF simulation takes long wall-clock time, and the spray data in “vof_spray.out” file can reach relatively steady state when solution time past certain value. I applied the “cyclic injection temporal type” and set proper duration and period to realize longer parcel injection duration using shorter VOF simulation. This strategy partially works. In parcel simulation, there are some parcels come out from the injector location after the initial injection duration, but all parcels seems only from the number one nozzle. That means only the first injection period has parcels from my multiple nozzles. At subsequent injection periods, the “multi plume” spray becomes “one plume” of the order number 1 nozzle.

Is there any suggestion to fix this issue? Should I change any nozzle settings? Thank you very much.

Sincerely,

Hi Mengqi,
Let me make sure I understand your issue. You first generated a vof_spray.dat file. Next, you used this file to set up the cyclic parcels introduction. In the simulation, the first injection cycle works well but starting from second cycle, parcels comes out from only one nozzle.

If this the case, have you tried to make a new vof_spray.dat file that covers the full simulation period? For instance, you can copy and past the content in the original vof_spary.dat until it covers the full period. Of course you should modifying the time accordingly.

Also, do you mind sharing your case setup so I can look into it in more detail?

Thank you
Chengqi

Hi，Chengqi

Thank you for your reply. Your understanding of my question is correct.

For your suggestion，it is quite hard to work in my case. My vof_spray.dat file has a size of 5GB with spray duration of 1ms. The first difficulty is that it is hard to edit a file with 5GB size. The second problem is that I need to perform a simulation of 1000 ms spray duration. That means by copy and paste I will get a 5TB file.

Sorry that it is not convenient to share my vof_spray.dat file directly. But I tested the cyclic injection setting using example case（ECN Spray G VOF and one way coupling）. At first，I get a vof_spray file with 9.5e-5s duration spray. Then go to one-way coupling simulation，set cyclic period of 10e-5s. I observed the same problem at the second period. Eight plumes become one plume.

Could you share your experience on how to fix this problem？ Thank you.

Sincerely

Mengqi

Hi Mengqi,
Now I understand the challenge here. Thanks for sharing the information. Let me work on this in more details and get back to you what we found.
At the same time, do you mind sending me an email so we can communicate easily? My email address is: chengqi.wang@convergecfd.com

Thanks
Chengqi