I am trying to simulate particle transport in a pipe using transient analysis due to the transient velocity profile at the pipe inlet. A certain amount of particles needs to be injected at time zero (or first time step) at the pipe inlet. However, under transient analysis, the particle injection method has to be mass flow rate or number rate. Can particles be injected using total number under transient analysis in CFX?
I have tried to use variable expressions to define particle mass flow rate which depends on flow time. For exampel, if time step was 0.001 s,
swtich = if(t < 0.002,1,0)
and in particle mass flow section I entered
mdot * swtich
where mdot represents the mass flow rate.
However this method does not work as it reports an error after the simulation has been run.
Any help is appreciated. Thank you.