particle track problem

[Alexander412]

Hello everyone,
I am simulating fumes and dust flow through gas shaft of a furnace. My problem is that dust particles seem to hit an invisible wall along the stream and disappear. I haven't got any idea why this happens. Maybe someone knows a solution to my problem.

shot of the problem

http://files.engineering.com/getfil...48b7-bfcc-bf5737d41c06&file=particletrack.png

another shot of the problem

http://files.engineering.com/getfil...be4-abd5-c5b606fb1e34&file=particletrack2.png

geometry

http://files.engineering.com/getfile.aspx?folder=49794d4e-4a45-4ff8-ae1f-4381d365ac48&file=geom.png