DPM Cone injection doubt
 

When using DPM and setting the injector a cone, one must especify diameter of the particle, velocity magnitude of the stream and total mas flow.

My doubt is why?, if density is already set in material propiertes then I'm overdimensionning the mass flow eq:

Mass flow = Density*Area*Velocity

In souch case, velocity shouldnt be specified, which if I left as 0 then the injector wont inject in a cone form. And setting mas flow as cero, well, it wont inject nothing.

Can somebody explain me why do I have to specify the four parameters?

Thanks!

Hi VIncenzo,

The DPM approach uses parcels instead of real droplets.

Each parcel carries a constant number of droplets that share the same behaviour (same temperatures, velocities, diameters, etc.).

Basically, the code doesn't know how many droplets each parcel contains.

He needs this information in order to correctly calculate the source terms in the gas equations in case of two-way coupling (if your parcel evaporates, it lose a certain amount of mass dm, the vapour produced should be n_of_droplets*dm)

Once you gave the diameter, you define the mass of a droplet inside the parcel, to determine how many droplets the parcel contains you have to give the massflowrate so that the codes can calculate n_of_droplet=massl_flow_rate/mass_of_droplet.

Hmmm I see it now, thanks for clarification!

Another question. I guess if I set a monitor in outlet to check mass flow, then the mass flow it goes out the model is then the mass coming from inlet+the evaporated from injection, right?

Normally the outflow should be a balance of both liquid and gazeous phases, but it strongly depends on your boundaries.