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-   -   creating and following a single particle (https://www.cfd-online.com/Forums/fluent/86839-creating-following-single-particle.html)

orland April 4, 2011 04:37

creating and following a single particle
 
hi,
i have an unsteady flow, and would like to follow a single particle initially at a specified location at rest.
anyone know how i can (a) create a single particle and (b) follow it?

Amir April 4, 2011 08:41

Hi,
define->injection->create->single
to track particles in unsteady flow, you can make an animation or with a UDF that execute at the end of each time step, write your desired data.

orland April 4, 2011 10:57

I still have a few problems:
 
1. the injecton wouldn't give a single particle but a stream
2. you can't define number of particles but only mass per time (i tried to put in a mass of exactly 1 particle. it didn't work)
3. can i define the injection to be at zero initial velocity?
4. once i do have the stream, how do i identify the 1st particle to assign the UDF to it specifically?

Amir April 4, 2011 17:41

Quote:

1. the injecton wouldn't give a single particle but a stream
you can inject any particle number in your stream by adjusting 3 parameters:
a)start and stop time of injection
b)particle flow rate
c)particle time step in DPM panel
Quote:

2. you can't define number of particles but only mass per time (i tried to put in a mass of exactly 1 particle. it didn't work)
refer to:
http://www.cfd-online.com/Forums/flu...injection.html
Quote:

3. can i define the injection to be at zero initial velocity?
particle initaial velocity can be set in injection panel
Quote:

4. once i do have the stream, how do i identify the 1st particle to assign the UDF to it specifically?
look, each stream is identified by its first particle in that but note that in unsteady case, when new particles are injected, you can imagine that new streams are generated that can be identified with their first particles.


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