{"id":168861,"date":"2022-04-25T10:09:34","date_gmt":"2022-04-25T10:09:34","guid":{"rendered":"\/forum\/forums\/topic\/solid-particles-in-a-nozzle-dpm-concentration\/"},"modified":"2022-05-17T16:48:38","modified_gmt":"2022-05-17T16:48:38","slug":"solid-particles-in-a-nozzle-dpm-concentration","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/solid-particles-in-a-nozzle-dpm-concentration\/","title":{"rendered":"solid particles in a nozzle, dpm concentration"},"content":{"rendered":"
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Hi,<\/p>\n

I have already asked a question related to the dpm concentration in a nozzle (\/forum\/discussion\/35817\/small-particles-gas-flow-in-a-nozzle#latest<\/a>). Basically, I needed to inject some particles (20 micrometer of diameter) in a converging-diverging nozzle. Using a surface injection with a structured mesh 190×50 and 2d-axisymmetric geometry, I encountered a dpm concentration error (the dpm concentration in the cells near the axis was about 300 Kg\/m^3, a clearly wrong value, while in the rest of the nozzle was about 2 kg\/m^3). Thanks to your help, I found out that a possible solution was to use the "scale flow rate by surface area" option. Enabling this option allowed me to have a good and correct result, with no more wrong dpm concentration near the axis of the nozzle. However, by applying this strategy I cannot reach a uniform mass injection along the radius at the inlet of the nozzle, obviously beacuse in a 2d-axisymmetric simulation the volume of the cells near the axis is smaller than the volume of the outer cells. So the scaling of the particle flow rate by surface area resulted in a smaller mass of particles injected near the axis and a greater mass of particles injected in the outer region. <\/p>\n

Now, I need to inject a uniform mass distribution all along the radius, so I cannot anymore apply the "scale flow rate by surface area". Are there other options to solve the dpm concentration problem?<\/p>\n

I leave here some details about the simulation:<\/p>\n

1) mass flow of the gas: 2.15 Kg\/s<\/p>\n

2) Mass flow of the particles: 0.92 Kg\/s (more or less the 30% of the gas flow).<\/p>\n

3) dpm model<\/p>\n

4) surface inj (every parcel is injected from the centroid of the cell at the inlet along the radial direction)<\/p>\n

5) B.C.:<\/p>\n

Inlet: pressure inlet, P_tot= 1034000 Pa, T_tot= 555.6 K.<\/p>\n

Outlet: Pressure outlet, non reflecting<\/p>\n

Wall: specified shear all set to zero (in order to achieve a slip condition but with a real viscous flow), no heat flux, dpm trap.<\/p>\n

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