Particles and continuous fluid

brahmarishiraj · May 17, 2014, 04:26

Dear Glen,

Here is the link for the files which i was talking about.

http://tbf.me/a/BcOAxB

(1)I want your opinion on whether modeling is correct.

(2)I have defined coeff. of restitution as 1 (with respect to wall) for water as well as sand to check how much sand gets trapped by water droplets.
I don't know why in "Particle fate diagnostic" (in output file) the number of sand particles entered and leaving the domain are same?
I expected that some of sand particles should get trapped by water droplets.

(3) How to calculate the efficiency of the scrubber?
(4) what should be the initial particle dia. of water? I have defined as 100 microns.

ghorrocks · May 17, 2014, 06:58

I am in dozens of conversations on the forum at the moment. I cannot remember what simulation you are talking about. You will have to describe the key points or provide a link to where it is discussed.

I do not have time to look at your setup either unfortunately. Maybe other will.

You best bet to get a useful answer on the forum is to ask focussed questions - general questions like "Is this going to work" rarely get useful replies.

You can answer some of your questions yourself. Have a look at the checks you should run described here: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

brahmarishiraj · May 17, 2014, 23:11

Dear Glen,

I am talking about the atomization in a venturi scrubber.

Here is the link for the earlier discussion:

http://www.cfd-online.com/Forums/cfx...flow-rate.html

(1)I have defined coeff. of restitution as 1 (with respect to wall) for water as well as sand to check how much sand gets trapped by water droplets.
I don't know why in "Particle fate diagnostic" (in output file) the number of sand particles entered and leaving the domain are same?
I expected that some of sand particles should get trapped by water droplets.

(2) How to calculate the efficiency of the scrubber?
(3) what should be the initial particle dia. of water? I have defined as 100 microns.

ghorrocks · May 18, 2014, 08:02

I cannot see why you have set the coeff of resistution to 1 to "check how much sand gets trapped by water droplets". It has nothing to do with this. The coeff of restitution=1 on the wall just means the either a water or sand particle will bounce off the wall. It says nothing about the water and sand interacting. If you want to model the water/sand interaction have a look at the particle collision model (and especially the comments on where it is applicable).

How calculate efficiency? I am no expert in scrubbers, I have no idea. That is why they invented libraries so you can go there and look it up. But then people found that was too far to walk so they invented google. Either way, look in the literature for sensible performance measures for your device.

What is the initial diameter? See previous answer. How do I know? I have no idea what you are modelling (other than what you have described). If the inlet water particle diameter is not specified in whatever you are trying to model then it sounds like a fundamental parameter of the experiment/analysis was not described.

May 17, 2014, 04:26	Particles and continuous fluid	#1
brahmarishiraj New Member Join Date: Mar 2014 Posts: 23 Rep Power: 12	Dear Glen, Here is the link for the files which i was talking about. http://tbf.me/a/BcOAxB (1)I want your opinion on whether modeling is correct. (2)I have defined coeff. of restitution as 1 (with respect to wall) for water as well as sand to check how much sand gets trapped by water droplets. I don't know why in "Particle fate diagnostic" (in output file) the number of sand particles entered and leaving the domain are same? I expected that some of sand particles should get trapped by water droplets. (3) How to calculate the efficiency of the scrubber? (4) what should be the initial particle dia. of water? I have defined as 100 microns.

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May 17, 2014, 06:58		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	I am in dozens of conversations on the forum at the moment. I cannot remember what simulation you are talking about. You will have to describe the key points or provide a link to where it is discussed. I do not have time to look at your setup either unfortunately. Maybe other will. You best bet to get a useful answer on the forum is to ask focussed questions - general questions like "Is this going to work" rarely get useful replies. You can answer some of your questions yourself. Have a look at the checks you should run described here: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

May 17, 2014, 23:11		#3
brahmarishiraj New Member Join Date: Mar 2014 Posts: 23 Rep Power: 12	Dear Glen, I am talking about the atomization in a venturi scrubber. Here is the link for the earlier discussion: http://www.cfd-online.com/Forums/cfx...flow-rate.html (1)I have defined coeff. of restitution as 1 (with respect to wall) for water as well as sand to check how much sand gets trapped by water droplets. I don't know why in "Particle fate diagnostic" (in output file) the number of sand particles entered and leaving the domain are same? I expected that some of sand particles should get trapped by water droplets. (2) How to calculate the efficiency of the scrubber? (3) what should be the initial particle dia. of water? I have defined as 100 microns.

May 18, 2014, 08:02		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,871 Rep Power: 144	I cannot see why you have set the coeff of resistution to 1 to "check how much sand gets trapped by water droplets". It has nothing to do with this. The coeff of restitution=1 on the wall just means the either a water or sand particle will bounce off the wall. It says nothing about the water and sand interacting. If you want to model the water/sand interaction have a look at the particle collision model (and especially the comments on where it is applicable). How calculate efficiency? I am no expert in scrubbers, I have no idea. That is why they invented libraries so you can go there and look it up. But then people found that was too far to walk so they invented google. Either way, look in the literature for sensible performance measures for your device. What is the initial diameter? See previous answer. How do I know? I have no idea what you are modelling (other than what you have described). If the inlet water particle diameter is not specified in whatever you are trying to model then it sounds like a fundamental parameter of the experiment/analysis was not described.