# Pls. help with particle tracking

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 August 8, 2007, 23:06 Pls. help with particle tracking #1 Daddy Guest   Posts: n/a I am modelling the shape of a droplet when it hit the substrate in thermal spray coating. I am thinking of using particle tracking to model it. Anybody know how to set up a model. Pls. help me. I am quite new to CFX.. In the beginning, I created a plate and enclosue it by air. Then I crate a domain for plate (solid) and air (liquid) with heat transfer setting as well. Is it correct for particle tracking? I have velocity of the droplet, droplet diameter, initial temperature. Anybody know something, pls. help me. Thank you very much for your help

 August 9, 2007, 05:16 Re: Pls. help with particle tracking #2 Anderson T F Guest   Posts: n/a Hallo, Well, I am not a specialist on this kind of simulation, but lets try to help. First thing, I donīt think that particle tracking is suitable for this case (since you want to see only one droplet). If you want to see what happens with one droplet when it touches the substrate, then you will need a eulerian-eurelian approach. It is not a simply case, but I would try: - only one domain (you are not interested in the plate), like a cube with the size scale similar to your droplet size, with one of the faces as BC Wall (the substrate) and the 5 others as BC Openning. - the domain with two substances: air and the one of your droplet. - a good inital values definition. This is the point where you define the initial shape of your droplet. Try to calculate the Weber number of it...if this is small ( 1 ), considering it spherical is not bad. Then you must create a function to set the values of concentration of your droplet in the domain (1 inside the droplet and 0 outside). Check the tutorial with the free surface flow aver the bump for more details. - then a transient simulation with really small timesteps. I think you will need really accurate values for the variables (as surface tension and viscosity) as a function of temperture to get a reliable result. Hope it helps Anderson T F

 August 10, 2007, 02:43 Re: Pls. help with particle tracking #3 Dr. Flow Squad Guest   Posts: n/a There is a tutorial named "Butterfly valve" that covers the particle tracking set-up. -Dr. Flow Squad http://tinyurl.com/2gkjh8

 August 10, 2007, 03:45 Re: Pls. help with particle tracking #4 Trang Guest   Posts: n/a Thank for your reply, Anderson. However, in the case I would like to model the heat transfer and droplet deformation in one model, can I use the method as your advise. If I model droplet on the substrate as yours, how can I set up "create a function to set the values of concentration of your droplet in the domain" what does it mean? All the data I had includes initial temperature of droplet (at very high temperature), substrate, surface tension of droplet, initial shape of droplet is sphere. When the droplet hit the substrate, there will be heat transfer between them and then the droplet will deform from a sphere to a layer on the substrate. I am very appreciate your help.