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Julie August 8, 2002 13:47

Ever wondered abt this?-About transient DPM

I was to model transient simulation on particles realised in a room from the same location from start time t=2 sec to t=4sec.

My supervisor suddenly ask me this question, "If under steady airflow velocity condition in the room,the particle(s) released at time t=4 should follow the same trajectory path as the particle(s)released at time t=2 if it/they are injected at the SAME location."

Hence if u are able to trace the paths of 5 particles released at time t=2, and if at time t=4,another 5 particles are released all at the SAME locations of the previous 5, although there may be 10 particles in the room at t>4sec, there should be strictly only 5 trajctory pathlines since the velocity profile in the room is at steady state.

1.What he said does sound reasonable. Does anyone agree/disagree with what he said? If he is not correct, why?

2.Also, since under transient, when we click on display, it shows the current positions of the partciles, and we cant do a path tracking display. I was thinking to find out if his claim is correct, I will have to monitor the position displacement values of two particles released at different timings and see if the particle released later follows the same position displacement with the earlier particle. Does anyone has a better way to investigate?

Also, anyone has thought and experiment on the above thoughts, PLEASE let me know how are your results so that I can double check it against mine..

Sridhar September 3, 2002 11:20

Re: Ever wondered abt this?-About transient DPM

I can add some light to this issue. You might want to consider along these lines: When you are doing particle tracking, did you assume a "one-way or two way coupling"? If it is one way coupling, then I take the side of your supervisor. If it is a two-way(or a 4 way) coupling, unless there are some specific reasons(for ex. if your particle size and/or density is too small) then I would say the particle tracks will most certainly be different.

Hope this will add up to your thoughts.

Regards, Sridhar.

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