Benjamin Franklin & CFD - Cham

Philadelphia CFD ConferenceCombustion, turbulence and CFD;the population analogyApril 2010There are two reasons why CFD specialists should pay attention tochemically-reacting flows:1. without them there would be no engines, furnaces or chemical plant togenerate the chemically-inert flows to which attention is paid; and2. their study provides unique insight into turbulence which affects allflows.Let us now ask ourselves what Benjamin Franklinwould notice about turbulent flames if he cameback to advise us.I suggest that he would be struck by their obviousintermittency. At any one location, there may besometimes pure air, sometimes pure fuel, andmost of the time fragments of gas withintermediate fuel-air ratio and degree of reaction.Remembering how „savages‟ and colonists so oftenchanged places, he might have used the „populationanalogy‟ to describe flames.