Particle tracking, losses

Bookwalker · January 22, 2018, 07:23

Hey,

Can cfx tell me how many particles make it past a certain point, or just a percentage of them make it?

I have a flow through a tube which is connected to cylinders, with holes? I wanna know how many particles get stuck in the cylinders.

Thanks

Gert-Jan · January 23, 2018, 08:04

What you can do is create a subdomain inside the cilinder. In CFX-Pre you can set the subdomain to absorb all particles when the flow into this subdomain.
Ýou can only define subdomains on separate named 3D Volumes. So if you haven't defined a volume inside your cilinder yet, you need to create these first in your geometry and remesh your domain.
Take in mind that when the particles are absorbed, they leave the simulation. So, this approach assumes that their effect on the flow inside the cilinder is neglected. Also, they cannot re-entrain into the tube....

Bookwalker · January 25, 2018, 07:07

thanks

However when i switch the 3d volumes to a new body part in icem, i can only choose the whole volume as a subdomain. Do you have any input on that?

Gert-Jan · January 26, 2018, 05:03

Subdomains need to be defined in Pre, not in ICEM.......

Let's presume you create the mesh in ICEM. You already have a body point in the volume outside your cilinders. Then:
- Create additional body points in each cilinder.
- Create internal faces inside your cilinder to make sure that the additional body points are inside a closed volume (These internal faces separates the body point outside the cilinder from the body points inside the cilinder).
- go to Mesh>Part Mesh setup. There set the faces as "internal wall". Do NOT put inflation on them.
- After mesh generation, import it in Pre.
- Use all volumes in your Default Domain (or whatever you named it).
- Then create subdomains for each separate cilinder volume and set your absorption diameter. If you set it to 1e-20, all particles will be absorbed.

Cheers, Gert-Jan

Gert-Jan · January 26, 2018, 05:39

Probably you do not have to set them as "Internal wall". The mesher will detect it automatically as interfaces. Important in the part mesh setup is that you exclude these interfaces from inflation (i.e. prisms).

January 22, 2018, 07:23	Particle tracking, losses	#1
Bookwalker New Member Christian Buchgeher Join Date: Dec 2017 Posts: 4 Rep Power: 8	Hey, Can cfx tell me how many particles make it past a certain point, or just a percentage of them make it? I have a flow through a tube which is connected to cylinders, with holes? I wanna know how many particles get stuck in the cylinders. Thanks

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January 23, 2018, 08:04		#2
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,827 Rep Power: 27	What you can do is create a subdomain inside the cilinder. In CFX-Pre you can set the subdomain to absorb all particles when the flow into this subdomain. Ýou can only define subdomains on separate named 3D Volumes. So if you haven't defined a volume inside your cilinder yet, you need to create these first in your geometry and remesh your domain. Take in mind that when the particles are absorbed, they leave the simulation. So, this approach assumes that their effect on the flow inside the cilinder is neglected. Also, they cannot re-entrain into the tube....

January 25, 2018, 07:07		#3
Bookwalker New Member Christian Buchgeher Join Date: Dec 2017 Posts: 4 Rep Power: 8	thanks However when i switch the 3d volumes to a new body part in icem, i can only choose the whole volume as a subdomain. Do you have any input on that?

January 26, 2018, 05:03		#4
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,827 Rep Power: 27	Subdomains need to be defined in Pre, not in ICEM....... Let's presume you create the mesh in ICEM. You already have a body point in the volume outside your cilinders. Then: - Create additional body points in each cilinder. - Create internal faces inside your cilinder to make sure that the additional body points are inside a closed volume (These internal faces separates the body point outside the cilinder from the body points inside the cilinder). - go to Mesh>Part Mesh setup. There set the faces as "internal wall". Do NOT put inflation on them. - After mesh generation, import it in Pre. - Use all volumes in your Default Domain (or whatever you named it). - Then create subdomains for each separate cilinder volume and set your absorption diameter. If you set it to 1e-20, all particles will be absorbed. Cheers, Gert-Jan

January 26, 2018, 05:39		#5
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,827 Rep Power: 27	Probably you do not have to set them as "Internal wall". The mesher will detect it automatically as interfaces. Important in the part mesh setup is that you exclude these interfaces from inflation (i.e. prisms).