[orland]

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]

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]

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]

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

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:
Urgent help needed plz! No. of particles in surface injection

3. can i define the injection to be at zero initial velocity?

particle initaial velocity can be set in injection panel

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.