II.  3-D flow with solid particles

2.1-Physical Problem Description

The problem geometry and flow conditions are as described in the previously chapter. The additional physical complexity comes from the fact
that the air stream is now seeded with solid particles,which are uniformly distributed at the duc inlet. The volumetric loading of particles in the incoming air is 0.01%, corresponding to a volumetric particle flow rate of 6.4516*10^-7   m3/s.

 Density  (kg/m3) Diameter  (m) Initial velocity  (m/s) 1.2 E3 4.0 E-5 (10.,0.,0.)

2.2-Modelling strategy

The following modelling strategy is adopted :

• the total number of particles entering the domain is 1,925,257.56 per second. These are grouped into 64 parcels that are uniformly distributed across the inlet.
• Each of the particles represents 30,082.15 particles. Note that since we are dealing here with is essentially a statistical technique, it is unsual to have parcels representing a non-integral number of particles.
• All particles rebound perfectly from the walls.
• Gravity effects are neglected.

2.3-Particle creation

Using the "NavCenter" section of the STARGUIde  window, we set the basic features of our model. We choose the option Lagrangian Multi-phase from the "Multi-phase treatment" menu and in the "Two-Phase Lagrangian Calculations", we take the option On-Coupled.  Then, we have to set, by clicking the option Edit Dropplet Parcels, the initial diameter, density and temperature of a typical particle in the parcel, as well as its initial position coordinates and initial velocity components. To generated a uniform particle distribution over the inlet area, use the command DRGENERATE to specifiy different locations for nes sets of parcels.
The properties are set using the Droplet Properties dialog by clicking Edit Droplet Properties. It is possible to display the particle location within the overall model geometry in the droplets panel :

Plot of a particle initial conditions

At that level, the pre-processing task is now complete and it is advised to save all the model, write the problem and geometry file before starting the post-processing.

2.4-Computing and results

To plot particle tracks stoted in the file tut.trk :

• In the NavCenter window, click folder Post-processing
• Click Particle Tracks to display the corresponding  panel
• Select the Plot Particle Tracks tab
• Select option Segment or continuous from the Particle type button group
• Click Plot Track

The following figure present the plot of the particle tracks continuously :