CEE

The flashcards below were created by user hamm.jane on FreezingBlue Flashcards.

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)
• 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
• 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
• symbolized as hp
• It is found by the total length of the well-the length of the well before water
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: 2012-10-31 01:53:46 Tags: exam Folders: Description: :,( Show Answers: