# CEE

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1. Transformations
Chemical or biological modifications that influence the composition of a system or structure of a molecule
2. Transport
the physical displacement (or movement) of a chemical/ biological species over characteristic distances and timescales
3. fate
fate= transport (movement) +transformation (reactions)
4. Advection
• Fluid acts as a carrier for the material dissolved (molecules) or superspended (particles) in it
• Def: the transport of material caused by the net flow of the fluid in which a material is suspended (particles) or dissolved (molecules)

• Formulas:Concentration*Volume/ area *time
• or concentration*distance traveled*area/ area* distance traveled/ velocity
• which is concentration*velocity.
5. overall flux
the sum of the advective, diffusive, and dispersive movements.

units: mass (or Mol)/ area*time
6. Diffusion
• molecular diffusion:
• The net movement of material from a region of high concentration to a region of low concentration caused by the random motion of material

• Influenced by
• 1.) Temperature
• 2.) size
• 3.) median (^ density, then lower diffusivities)
7. Osmosis
Diffusion of water (only) -water molecules move up salt gradients and down water gradients
8. Ficks law
Jdiffusivityis proportional to - change in concentration gradient/ change in distance

Jdiff= -D (dc/dx)

diffusivity is chemical dependent
9. Characteristic distance

the distance, x, a molecule or particle will travel in a time t
10. Diffusion/ Brownian motion
• 1.) results from random motion of the particle and collions with other particles
• 2.) movement from high to low concentrations
• 3.) much slower than molecular diffusion because particles are larger relative to molecules
• 4.) Fick's law applies, but d is more complex
11. Cc
the cunningham slip correction factor
12. Stoakes Einstein Relation
D=K*T/F   where K is the boltzman constant, f is the friction coefficient and T is the temp in Kelvin

F= 3*pie*fluid viscosity*particle diameter/ Cc
13. diffusion occurs faster in?
air than water
14. How does transfer occur at boundries
Through diffusion b/c advective velocities approach zero at those interfaces
15. k
• km
• k is the mass transfer coefficient
16. If Jboundary < 0
then Cboundary > Cbulk and flux is from boundary to bulk fluid
17. If Jboundary >0
Cboundary< Cbulk   and flux is from bulk fluid to boundary
18. Diffusion through a stagnant layer
• If Jbound= km (Cbulk-Cbound)= -Jdiff
• then km= D/L   where D is diffusivity and L is the boundary layer thickness

Jdiff
19. Diffusion through  settling particles that stick to the interface
• Cbulk=C
• Cbound =0
• Jg= velocity* (Cbulk-Cbound ) = velocity * C
• therefore k= velocity
20. penetration theory
accounts for the temporal varience in the concentration gradient as material is lost to the medium

Use when contact time b/w the boundary layer and the bulk fluid is less than t=L2/ 20  (ie the time when constant concentration gradient has not yet been established)

• a time dependent process
• km=(D/pie*t)1/2   instantaneous K

km= 2 (D/pie*t2-t1)1/2   Averaged km where t2-t1 is the time interval of interest
21. film theory
a time dependent process
22. Boundary layer Theory
• 1.) accounts for advection and diffusion
• 2.) in reality, both adv and diffusion happen simulataneously
• advection dominates far from boundary layer
• diffusion dominates close to boundary layer

km= 0.323(u/x)1/2*v-1/6D2/3   at a position x, where u is fluid velocity, x=position, D=diffusivity, v= dynamic fluid viscosity/fluid density

• Boundary layer averaged over length L
• km=0.646 (u/L)1/2 *v-1/6*D2/3
23. porosity
• porosity= pore volume/ total volume porosity of air
24. Density
solids density, ps= mass solids/ volume of solids

bulk density, pb= mass solids/ total volume

pb=ps(1- )
25. hydraulic conductivity
K

• the stuff that is resisting the flow in the tube
• it is measured in Length/time
• it is constant for a particular soil/sand
• depends on the sand pore size/ grain size
26. Darcy's Law
where K is hydraulic conductivity and A is area and Q is flow
27. velocity
28. Find velocity in a water saturated porous media
where U= linear velocity, K=hydraulic conductivity and dh/dl is change in height/ change in length

it is - to remind that flow is down the hydraulic gradient
29. Find velocity in any fluid-saturated media
• where U =linear velocity
• k= intrinsic permeability
•  = viscosity
• dp/dl= the pressure derivative
30. If Uwater=Uany fluid
-K(dh/dl)= (-k/mu)(dp/dl)

where dP=pw*g (dw)
K=k/mu
where mu is viscosity of water and k is intrinsic permeability
31. When can you optimize K? hydraulic conductivity?
where K =hydraulic conductivity, k+ intrinsic permeability, pw=pressure of water, g=gravity and mu is viscosity of water
32. Aquifers
water in a saturated zone that exists in the subsurface
33. recharge area
• where surface water can infiltrate the ground. Not much runoff
• -has high permeability
34. Confined aquifer well
will pressure water up
35. How to determine direction of water flow?
find hydraulic head (h) -height
36. hydraulic head
• h=hp+z
• hp= pressure head
• z= elevation head ( distance between some zero level and the bottom of the well where the zero level is deeper)
37. How do you find the water level?
• hA= hpA+zA   where hpA= pressure head for well A and zA=elevation head for well A
38. What is the hydraulic gradient?
With regard to an aquifer, the rate of change of pressure head per unit of distance of flow at a given point and in a given direction.

dh/dl=    where hA is water level, and xA-xB is distance  the wells are apart
39. Pressure head
• symbolized as hp
• It is found by the total length of the well-the length of the well before water
40. elevation head
distance between some zero level and the bottom of the well, where the zero level is deeper
41. Diffusion in Porous media
Jdiffusion= -Deffective diffusivity*(dc/dx)

Deffective diffusivity=  where theta a is air-filled porosity
42. Dispersion in porous media
Jdispersion = -effective difusivity*(dc/dx)

eff=h=Deff +U

where  is dispersivity in porous media, Deff= effective diffusivity, U= filtration velocity
43. 1st order reaction
• -rxn=-kCw
44. 2nd order reaction
-rxn=-k[reactant]Cw
45. accumulation rate
accumulation rate=inputs-outputs+formation rxn-rxn

dC/dt=QinCin+vsCairA- QoutCw- kCwV
 Author: hamm.jane ID: 180807 Card Set: CEE Updated: 2012-10-31T01:53:46Z Folders: Description: :,( Show Answers: