M E 433
Professor John M. Cimbala
Today, we will:
•
Continue our discussion about gradient diffusion
•
Discuss the Reynolds analogy
•
If time, begin to discuss the Gaussian plume model
Lecture 13
Reynolds Analogy – Energy, momentum, and mass, all diffuse in similar fashion. Compare:
Suddenly heated wall [T = T0 = 0oC everywhere, then suddenly T = Ti at the wall.]
z
Time
increasing
Energy flux
T0
Ti
T
Suddenly moving wall [U = U0 = 0 m/s everywhere, then suddenly U = Ui at the wall.]
z
Time
increasing
Momentum flux
U0
Ui
U
Sudden removal of a membrane [cmolar = cmolar,0 = 0 mol/m3 everywhere, then suddenly cmolar =
cmolar,i at the location of the membrane, and the membrane disappears suddenly).]
z
Time
increasing
Mass flux
cmolar,0
cmolar,i
cmolar