CHE3123 Chap15BW

# CHE3123 Chap15BW - CHE 3123 Momentum Heat and Mass Transfer...

This preview shows pages 1–9. Sign up to view the full content.

CHE 3123 Momentum, Heat and Mass Transfer II “Review Momentum Transport (as in 3113) Newton’s τ μ dv velocity viscosity law dy (eq.7-4) viscosity direction stress of momentum (force/area)

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
y fluid moving v along a plate x Fluids that obey this law (water etc. ) are called “Newtonian”
Besides looking at τ as a stress, or force per unit area, we can also look at τ as, momentum transport per time per area. That is momentum is being transported towards the plate by “fast” particles of fluid rubbing against relatively slow particles Look at units of τ τ force N kg-m area m 2 s 2 .m 2 kg m 1 1 s m 2 s

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
(mass) (velocity) momentum area . time area . time HEAT TRANSPORT You will find heat transport easier to understand. Momentum transport involves the transport of a vector quantity, momentum. But heat transport involves only a scalar quantity, thermal energy.
The relation in heat transfer which is analogous to Newton’s law of viscosity is Fourier’s law heat/time temperature Fourier q x k dT Law A dx area to thermal direction direction of heat conductivity of heat flow transport

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
A more general form of this, in vectors notation, is q k T A Observe that q x a flux A energy,momentum,mass stuff (area) (time)
As this mention of “stuff” suggests, let us write down the third important equation for this course conc. Fick’s first J A,z D A,B dc A law dz (eq 24-15) molar flux diffusivity in z direction (of component A)

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Note that the gradients or driving forces for the three transfer phenomena are dv a velocity gradient dz dT a temperature gradient dz dc A a concentration gradient dz
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern