This is really helpful. Thank you again for your comment nI definitely want to try the particle with lower density. I will definitely let you know about the results. nSorry I was not clear in the earlier comment. My project is about Optimization of a Nozzle. nThis nozzle design which I was running simulation above is the original design of a company. But they want me optimized it and compare it with the original one.nSo, I have designed an optimized nozzle and run the simulation with the same boundary condition and the used same particle but It runs well with that optimized nozzle( make it to the outlet) but I don't know why the same condition doesn't work with this one. Maybe I am wrong with selecting the particle. I will run the simulation again with different particles.