Expert: Paul Soderman - 3/5/2010

Question
Dear Mr. Soderman,

This must be a very strange question for you. But I am doing a small experiment and I would like to add some deep science to it. I smoke pipe and part of the process is to get a very cool smoke coming into your mouth. An easy way to do it is living a small air pocket in the bottom of the bowl, and you achieve that by packing the tobacco carefully at the top of the bowl. I found that if I put a small Stainless Steel ball in the bottom of the pipe bowl you do not have to worry about the packing part because even if you stump the tobacco down your bowl it is no going to get to the bottom. Also, the steel ball do not get enough heat to get hot; on the contrary it stays cold and that helps to cool the smoke. Now my question is if you imagine the smoke coming from the top of the pipe and passing through either the air pocket or the stainless steel ball, is the behavior of the smoke the same in both cases? Does the ball causes a better distribution, or ease the flowing of the smoke? Or basically nothing happens and I am over engineering my little experiment. Thank you so much

Answer
Alfonso
Since the smoke has to go around the steel ball or through the air pocket, the ball is causing some blockage relative to the air pocket case. I assume the smoke speeds up locally around the ball and there is some increased flow resistance.  But at low flow rates, it may be hard to see the difference.  You should be able to determine relative resistance as you draw.  Only you can complete the experiment.
Paul