Fluids

Fluids

Creating a particle flow but confused about how to interpret the results ?

    • Lylad
      Subscriber

      Hi I am creating a simulation with a cow releasing infectious aerosol, I can created my flow and while running my particle results I have been using the colour by discrete phase variables and DPM concentration. But I am just a bit confused about the units it says the units are kg/m^3, so I am just a bit confused what this meaning in terms of concentration and how it can be interpreted.

      Also when trying to change the units I noticed the default for DPM concentration says 1.e15-particles/ kg, I am also confused what this means?

      Thank you :)

    • Rob
      Ansys Employee
      There aren't alternative units for DPM Concentration, but there are for concentration. I think the particle-conc is something else, especially as it's per kg, lb or g but the 1e15 remains constant.
    • Lylad
      Subscriber
      Hi rob thank you so much for your reply, I just wanted to ask another question, when your creating the injections one of the options for point properties is the Flow rate (kg/s) for the particles, the default value is 1e-20, but is this something you need to calculate beforehand ?
      If so is there a formula to calculate the flow rate ?
    • Rob
      Ansys Employee
      You need to give the solver a flow rate if using two way coupling. The 1e-20 kg/s is for one way as the solver needs a mass for something. Historically if we were just tracking particles one way (flow affects the trajectory but trajectory doesn't alter the flow) we set a mass of 0 kg/s.
      Flow rate is how much mass you want in the system. We use a parcel method so you're tracking the parcel not the particle: not helped that everyone always muddles the two terms.
    • Lylad
      Subscriber
      Hi rob thank you for your reply, I am using a one- way simulation so that fine but would it be best to leave the flow rate at 1e-20 or change it to 0 as you said.
    • Rob
      Ansys Employee
      Don't change to zero. You won't get any particles if you do that! So leave the mass flow as 1e-20.
    • Lylad
      Subscriber
      Thank you so much :)
    • Rob
      Ansys Employee
      You're welcome.
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