Learning Forum

[Ayushman Srivastava]

Driver section = helium gas, Driven section = air, Species transport model is ON. After initializing, I went under the patch section and I patched the driver with helium and gave the value 1. Then I checked the contour of species of mass fraction of Helium in the entire domain and found that in the driver section, Helium is there and in the driven there is air. When the diaphragm ruptures practically, the mixing of helium and air takes place.

Is it the right way to patch? On what basis this value should be selected? While patching the driver with helium, I entered the value 1. Is this a mass fraction of Helium?

I am using the DPM model to inject the particles and particles coming out of the nozzle orifice at high velocity. How to calculate the mass fraction?

2nd question is- Shall I take the Gamma value (Cp/Cv) of the mixture of helium and air? If yes then where to input it? 

[Rob]

You need to set the conditions to suit the model. If it's all helium then the patch will either be helium fraction one, or air fraction zero depending on how you set up the species mixture. You may also need to patch pressure into zone(s). 

What are the particles doing? Remember DPM doesn't have a volume fraction, and check the definition of DPM Concentration before using that data elsewhere. 

[Ayushman Srivastava]

Suppose I have to inject 50 particles.

what type of injection shall I select i.e., either group or surface or else? 

By the way I selected group injection and number of streams = 20. Mass flow rate = 0.001 kg/s. and my study is transient. How to calculate the total number of particles injected after the simulation ended? 

[Ayushman Srivastava]

How to convert mass flow rate into the number of particles injected per unit time?

[Rob]

Please read the section on Parcel Theory. The mass injected and number of particle (parcel) streams don't need to agree. 

[Ayushman Srivastava]

Are no. of streams and no. of particles same?

[Rob]

Streams and parcels are likely the same, images of what your comparing would be useful. 

[Ayushman Srivastava]

[Ayushman Srivastava]

 

so the no. of streams/no. of parcels/no of particles is the same thing? when I simulate for 1 time step, in the console it shows that  

Updating solution at time levels N and N-1.

done.

Injecting 20 particle parcels with mass 2e-09 at t = 0

number tracked = 20

Advancing DPM injections ....

number tracked = 20

Flow time = 1e-07s, time step = 1

 

Updating solution at time levels N and N-1.

done.

Injecting 20 particle parcels with mass 2e-09 at t = 1e-07

number tracked = 40

 

Advancing DPM injections ....

number tracked = 40

Flow time = 2e-07s, time step = 2

Please clarify whether it means that in each time step, in one parcel = the injected particle is 20.

 

[Rob]

Streams = parcels. Each parcel will then contain a (potentially fractional) number of particles. As it's transient you probably don't have access to stochastic tries, so you may find you need to increase the number of streams. 

[Ayushman Srivastava]

micro-particles at high velocity are penetrating the gelatin like material which is similar to skin. I want to know the penetration depth covered by micro-particles.

Which software can be used for such analysis?

[Rob]

Please post a new thread in the Ansys Products room.