See the attached file.
1. Hershel-Buckley
The Hershel-Buckley model describes the behavior of a fluid that behaves in an unusual manner (rheology; see http://www.tipmagazine.com/tip/INPHFA/vol-10/iss-2/p29.html). The BH equation is given as (also given in attachment 0gl99112):

shearing stress=yield stress + consistency (shear rate) ^ power law exponent

The three parameters of HB are yield stress, consistency and shear rate. BH model requires a certain amount of stress (a threshold) to initiate flow but require less stress as sheer increases. Yield stress is the amount of force required to cause deformation. Consistensy describes the ability to flow. Its range is dependent on temperature and solute content. Sheer stress is defined as the force divided by the area parallel to the force. From my understanding the ranges of these parameters depends on the material and experiemtnal design. I've found a few studies for you to review for more information (the last link is a good overview):
http://www.blackwell-synergy.com/doi/full/10.1111/j.1365-2621.2004.00923.x?cookieSet=1
http://cat.inist.fr/?aModele=afficheN&cpsidt=1959601
http://sst-web.tees.ac.uk/external/U0000504/Notes/colloids/colloids07/FdRheo02.html

Other alternative rheology models are:
Newtonian model- having a linear proportional relationship between shear stress and sheer rate
Power law model- behaves like the BH model except that there is no minimal amount of stress needed to initiate flow.
Bingham plastic model- provides a linear proportional relationship between shear stress and sheer rate as in the Newtonian model but like the BH model it requires a minimal amount of stress to initiate flow.

References:
http://www.glossary.oilfield.slb.com/Display.cfm?Term=Herschel-Bulkley%20fluid
http://www.glossary.oilfield.slb.com/DisplayImage.cfm?ID=388
http://www.lsbu.ac.uk/water/hyrhe.html
http://en.wikipedia.org/wiki/Rheology
http://en.wikipedia.org/wiki/Non-Newtonian_fluid

2. Creep Test:
In this test the material being tested is subjected to constant compression or tension at a constant temperature resulting in increasing strain. Failure occures if the material ruptures. If the material doesn't fail the reformation time can be measured. Viscoelasticity is the ability of a material to not only resist shear strain and flow but also to regain its original shape following deformation.

Reference:
http://www.instron.com/wa/resourcecenter/glossaryterm.aspx?ID=34
http://en.wikipedia.org/wiki/Viscoelasticity

3. Relaxation test:
In this test material is subjected to constant strain resulting in the use of decreasing stress (or force). Again this can provide a means for determining the viscoelesticity of a material by testing the ability of the material reform under decreasing stress. It is the counter-part to the creep test.

Reference:
http://www.azom.com/details.asp?ArticleID=2678

4. Capillary tubes
These are glass tubes designed to exhibit capillary action. They can be used to measure the ability of a bubble to move through a viscoelastic material. Various rheology measurements can be taken using these tubes and other machinery such as a rotational and filament stretching rheometers.

Capillary action is defines as

Height of a liquid column= (2(surface tension) (cos contact angle))/densityxgravityxradius

For water this simplifies to height= (1.4x10^-5)/radius. This would be very different for viscoelastic materials.

Limitations:
-The cappilary tubs can contribute 'noice' due to the uneveness of the interior wall and the tube size can be a limitation.
-Limited use as viscosity increasses.
-Cannot be used to measure non-Newtonian fluids.
-Steady state behavior make take a long time for complicated fluids.

Advantages:
-Permits sampling of small amounts of materials.
- Additional sources of pressure can be used to expand the range being measured.
-Simple proceedure.

Reference:
http://en.wikipedia.org/wiki/Capillary_action
http://www.findarticles.com/p/articles/mi_qa3740/is_199711/ai_n8762324
http://ej.iop.org/links/r9ujeOh0m/1OOmDltz2xGUM2tpav5vpA/siv1i4p111.pdf
http://en.wikipedia.org/wiki/Viscometer

5. Rotational Rheometers
These measure the force required to turn an object in a marterial.

Geometrics:
This equipement relates the torsional stress of turning the object in a material to the dynamic viscosity.

Fundamental equations:
The calibration constant (k) for determining torque is calculated the viscometer using the equation: k = v / d t in which v is the known viscosity of the liquid in centipoises, d is the specific gravity of the liquid tested, and t is the time in seconds for the liquid to pass from the upper mark to the lower mark.

Limitation:
-difficult to measure low viscosity fluids due to friction inherent in the rotational axis and motor.

Advantage:
-Can measure non-Newtonian fluids.
-Good for measuring fluids with higher viscosity.