# How to get number of particles escaped through a zone?

 Lets say we have uniformly distributed rain particles released from inlet. Lets say we have two outlets (outlet-1 and outlet-2). Air carries the particles and some escapes through outlet-1, some gets trapped at the walls, and some escapes through outlet-2. Assuming that the rain particles don't evaporate or coalescent. Also assuming that the rain does not effect the air flow filed. How to find the mass-fraction exiting, lets say, outlet-1? Since particles are uniformly distributed, particle-fraction should equal mass-fraction. So if we determine how many particles are released (tracked) and how many are escaped through outlet-1, then we can find the particle-fraction.The more particles is releaseed, the better accuracy you get in the ratio of particles trapped and exited. If you release particles from a surface, you get the same number of particles tracked as the number of faces on that zone. If you want to release more particles, then you can create a plane with a specified number of points. How to create such plane:-Display the surface-Surface->Plane -Click on "Select Ponts" -select three points on the surface with right-mouse-botton -click on "Plane Tool" The plane tool will be snapped on the 3 points. -select "Bounded" and "Sample" points -Select large number for "Edge" 1 and "Edge 2". If you select 100 by 100 you will have 100*100 points on the plane. Since it is bounded, you will have only those points that fall within the domain. You may have to move the plane tool slightly into the domain. -click on "Create"-Create an injection released from the plane just created. You need to provide the diameter of the particle, and the initial velocity. You can get the xyz velocity of the fluid and make it equal to the particle.-Report -> Discrete Phase -> Sample -select the outlet under Boundaries -select the injection -click on compute In the cortex window, it will report TOTAL tracked, escaped, aborted, trapped, evaporated, and incomplete. Also, you will get one file per zone selected. This file will have particle information for all the particles *escaped* through that zone. All you have to do is count (of course with a text editor) number of raws (lines) in the file. The number of raws gives you number of particles escaped. Then you will know how many particles escaped through this zone.