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-   -   How to model a moving droplet source? (http://www.cfd-online.com/Forums/flow-3d/27357-how-model-moving-droplet-source.html)

James March 5, 2009 13:27

How to model a moving droplet source?
 
Hi,evryone:

I am modeling a droplet coating process. The droplet source moves, relative to the base material. The Droplet Source Model says that the droplets are generated at a fixed location. Can I let the droplet location coordinates be a function of time? Thanks!

James

HC March 5, 2009 20:36

Re: How to model a moving droplet source?
 
Maybe you can do some customization in qsadd.F and modify the array xdrop, ydrop and zdrop after each cycle, to mimic the location change.

James March 6, 2009 12:02

Re: How to model a moving droplet source?
 
Thank you! Can I let the base material move instead and let the droplet source be stationary?( Or Can I use the mass momentum source model to do this modeling? I don't know what the difference is between the droplet source model and the mass momentum source model. It seems that the latter can do the same thing as the former.

HC March 6, 2009 12:36

Re: How to model a moving droplet source?
 
I am not sure what you meant by letting the base material move. If you are talking about using moving object model, you may need to give some more details on how you want to set up the problem; if it is about non-inertial frame, I am afraid that it won't be applicable as the non-inertial frame will be applied to the whole domain which includes the sources.

About the difference between the two models, when the droplet bubble source model is applied, numerically the droplets/bubbles would just replace the surrounding fluid in one step, while the fluid from the sources will try to push the surroundings when the mass/momentum source model applied. Also, in the droplet bubble source model, the droplets/bubbles has a spherical shape. In the mass/momentum source model, the fluid would come out in a stream.

James March 6, 2009 12:50

Re: How to model a moving droplet source?
 
HC, thank you very much! When I mentioned letting the base material move, I mean there is a relative movement between the droplet source and the base material. So there are two ways to model it. One way is to let the droplet source change its location during the process; the other way is to let the base material move, relative to the droplet source. But I think the latter way may need larger computational domain. Is that right?

HC March 6, 2009 12:57

Re: How to model a moving droplet source?
 
Yes, it sounds about right, as long as you the motion properties of the base material.

James March 6, 2009 14:00

Re: How to model a moving droplet source?
 
Thank you very much! I know the motion path of the base material.

James March 6, 2009 17:19

Re: How to model a moving droplet source?
 
So I should use the moving object model to do this? By the way, do you mean the Moving Solid Phase model by moving object model? Thanks!

HC March 6, 2009 17:37

Re: How to model a moving droplet source?
 
It depends. If the base material is flat, you may just use a wall boundary to mimic the base material and specify the velocity at that wall boundary. Or as you said, you can turn on the moving object model and create a moving component to mimic the base material.

James March 8, 2009 01:31

Re: How to model a moving droplet source?
 
Thank you! Since I need to model the internal heat transfer within the base material, I cannot just set it as a rigid wall boundary. Then I will use the Moving Solid Phase Model. Is it the same thing as Simple Moving Objects?


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