Compute the fluctuating velocities from V²f model

zahrae · October 20, 2021, 10:45

Hello!

I'm using V²-f turbulence model to be able to compute the normal fluctuations as it impacts the deposition of particles. I run the simulation and now I don't know how to compute the fluctuating velocity of the flow. Someone can help me.

Thank you in advance!
Regards.

LuckyTran · October 20, 2021, 13:08

Hmmm, not sure why you are stuck trying to compute things. The velocity variance (v2) is readily available if you are using the v2-f model. Are you just trying to take the sqrt of it or what? That's also pretty straightforward with a custom field function.

zahrae · October 20, 2021, 16:11

Thank you for the reply, sir!
I need to use the velocity fluctuations computed by the v²-f model to change the DRW model based on the equation below, for more accurate results (the DRW overestimate the deposition of small particles )

kmodified= 3v²/2 for y+ < 30

I have another question if you don't mind, how can I change the DRW equation I wasn't able to find a macro to change it?

Inthavong [1] mentioned in his paper that "With the v 2–f model, the v' profile may be obtained directly from the flow field and is used to modify the TKE as kmodified= 3v²/2 for y+ < 30"
should I use the Define profile macro?
Regards.

[1] Inthavong, K., Tu, J. and Heschl, C., 2011. Micron particle deposition in the nasal cavity using the v2-f model. Computers & Fluids, 51(1), pp.184-188.

zahrae · October 21, 2021, 06:42

Any help sir! I will be very grateful!

October 20, 2021, 10:45	Compute the fluctuating velocities from V²f model	#1
zahrae Member imane Join Date: Aug 2018 Posts: 61 Rep Power: 7	Hello! I'm using V²-f turbulence model to be able to compute the normal fluctuations as it impacts the deposition of particles. I run the simulation and now I don't know how to compute the fluctuating velocity of the flow. Someone can help me. Thank you in advance! Regards.

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October 20, 2021, 13:08		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,673 Rep Power: 65	Hmmm, not sure why you are stuck trying to compute things. The velocity variance (v2) is readily available if you are using the v2-f model. Are you just trying to take the sqrt of it or what? That's also pretty straightforward with a custom field function.

October 20, 2021, 16:11		#3
zahrae Member imane Join Date: Aug 2018 Posts: 61 Rep Power: 7	Thank you for the reply, sir! I need to use the velocity fluctuations computed by the v²-f model to change the DRW model based on the equation below, for more accurate results (the DRW overestimate the deposition of small particles ) kmodified= 3v²/2 for y+ < 30 I have another question if you don't mind, how can I change the DRW equation I wasn't able to find a macro to change it? Inthavong [1] mentioned in his paper that "With the v 2–f model, the v' profile may be obtained directly from the flow field and is used to modify the TKE as kmodified= 3v²/2 for y+ < 30" should I use the Define profile macro? Regards. [1] Inthavong, K., Tu, J. and Heschl, C., 2011. Micron particle deposition in the nasal cavity using the v2-f model. Computers & Fluids, 51(1), pp.184-188.

October 21, 2021, 06:42		#4
zahrae Member imane Join Date: Aug 2018 Posts: 61 Rep Power: 7	Any help sir! I will be very grateful!