Fourier’s law states that heat flows down a temperature gradient (with proportionality constant k<\/em>, the thermal conductivity):<\/p>\n Fick’s law tells you mass moves from areas of high concentration to low:<\/p>\n Ohm’s law states that current moves down a potential gradient (and so electrons move up the gradient due to the dyslexic way current<\/em> is defined):<\/p>\n And Newton’s law of viscosity (which is a little more complicated-looking due to the way fluids can change their density) tells you momentum transports from locations of high velocity to low.<\/p>\n The negative signs in these equations are the second law of thermodynamics. Those negative signs are a consequence of the fact that the universe tends towards states of higher entropy or higher probability. Of course you can make<\/em> heat flow up a temperature gradient using, for example, an air conditioner. But that requires a machine, which is what you learn in a thermodynamics class. And that’s what separates “transport” from “thermo” for a chemical engineering student.<\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" It’s been a busy summer, and we’ve got a few exciting battery-related surprises coming up soon at the CUNY Energy Institute. This week I’m getting ready for the start of my Transport Phenomena I class at NYU. Transport phenomena is … Continue reading ![\"fouriers](\"http:\/\/www.joshuagallaway.com\/wp-content\/uploads\/fouriers-law.png\")
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