Another way to characterize the water mist system is by how the mist is generated: single fluid or twin fluid being the most popular methods. The simplest method (which is used in this study) utilizes only one fluid. The fluid travels through the piping and reaches the nozzle before flowing out of a small orifice in the nozzle and atomizing. The atomization is typically achieved due to the increased dynamic pressure from the ambient air on the fluid jet as a result of the differences in relative velocity between the fluid and the surrounding air. The other method of atomization is by having the fluid impact an obstacle at high velocity. In twin fluid systems, one fluid is the water and the other is a compressed gas (i.e. air, nitrogen, etc.). Inside the nozzle, the compressed gas is positioned in such a way that its spray will flow into the water and cause it to scatter. These twin fluid systems are more complex, more expensive, and require twice as much piping