Viscosity of Clotted Blood

http://en.wikipedia.org/wiki/Viscosity, Maybe something here.

Engineers don't typically know much about blood, outside the context of their own, "Blood, Sweat and Tears".

I have a reference from Diamond et al. (below) which describes clot behaviour as liner viscoelastic, but I am trying to simplify the model by approximating the clot as a fluid.

"Clot behavior is described by linear viscoelastic theory for small deformations, in which the complex dynamic shear modulus G is defined as in terms of the dynamic elastic modulus (which scales with the crosslink density) and the dynamic loss modulus (which describes viscous flow behavior and is much smaller)."

Only solids are defined in their behaviour by 2 modulus since one defines the elastic aspect and the second the internal losses. The stess is defined as the sum of an elastic term proprtional to the strain and a second term proportional to the derivative of strain versus time. As vectors the 2 are at 90° phase shift (in case of a sinsoïdal strain). Viscosity is related to the velocity proportional stress and since there is no flow it losses its meaning.

Look at the different models which combine 2 or more parameters for the properties definition.

You cannot simplify a combined elastic+internal friction behaviour as a simple fluid.

Explain what you want to simulate may be this way we can come to simple but nearer to reality model.

At which stage of clotting do you require data? Surely it gets thicker as time goes by

from a jelly-like substance to a solid?

• Viscosity and Clotting of Blood in Venous Thrombosis and Coronary ... by L DINTENFASS - 1964 - Cited by 34 - Related articles
  The viscosity of blood remains constant, at any rate of shear, during the first two to four minutes after removal of blood. Clotting starts after various ...
  circres.ahajournals.org/cgi/content/short/14/1/1
• Variations in Clotting Time, Relative Viscosity, and Other ... by RA SCHNEIDER - 1951 - Cited by 42 - Related articles
  From a study of clotting time, relative viscosity, hematocrit, erythrocyte sedimentation rate, and the prothrombin time of the blood, the following ...
  www.psychosomaticmedicine.org/cgi/content/abstract/13/5/289 - Similar
• [PDF] instrumentt to dynamic studies of blood viscosity during clotting. File Format: PDF/Adobe Acrobat - Quick View
  by R Yesner - 1951 - Cited by 8 - Related articles
  of the blood was constructed. The viscosity of materials that change their physical characteristics with time, suchas blood during clotting, is difficult to ...
  www.ncbi.nlm.nih.gov/pmc/articles/PMC2599143/.../yjbm00334-0067.pdf
• The effect of TiO2 nanotubes in the enhancement of blood clotting ... by SC Roy - 2007 - Cited by 28 - Related articles
  This cascade results in a rapid increase in the blood viscosity resulting in ... The density of the fibrin network density in the clotted blood was examined ...
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• PS Gel Because of its unmatched structural viscosity, PS Gel forms a highly stable barrier between the clotted blood and the serum. 4. Application ...
  www.npacorp.com/products/psgel.html - Cached - Similar
• IFMBE Proceedings 2509 - The effect of clearance upon friction of ... by S Afshinjavid - 2009 - Related articles
  (whole blood with Lithium heparin to prevent clotting) and then clotted blood as the lubricants for each joint. Viscosity of the non-clotted blood was found ...
  www.springerlink.com/index/u31355n62q452671.pdf
• A mathematical model for the dissolution of non-occlusive blood ... by I Serša - 2007 - Cited by 2 - Related articles
  blood clots. These forces originate from blood viscosity or turbulence and may considerably acceler- ate clot dissolution by eroding the clot's surface, ...
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• Prothrombin time - Wikipedia, the free encyclopedia They are used to determine the clotting tendency of blood, in the measure of warfarin dosage, liver damage, and vitamin K ..... Blood film · Blood viscosity ...
  en.wikipedia.org/wiki/Prothrombin_time - Cached - Similar Sponsored links Viscosity blood Relax. Take a deep breath. We have the answers you seek.
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Great ! You did a tremendous job at least one of the articles is very interesting since it couples the 2 parameters: the one related to the clott net and the other related to the shear (effect proportional to deformation velocity). GA from me.

I did not do your research what I wrote came from already known aspects.

If the guest wants to make a simulation he must introduce the factor time but how ?

What is the trigger ? It is not so easy.

Some very good input.

I am interested in modelling the behaviour of a "point in time" formed clot in whole blood, and its interaction with a mechanical device (I'm more interested in the device than the clot). I was HOPING to characterise the clot as a fluid with a higher viscosity for the purposes of keeping the model simple.

It seems that there is no viscoscity data available for a formed clot because it is characterised as a solid with dynamic elastic modulus and an internal loss component. I'm looking at 2 options; A) model the clot as a solid or B) make up a viscoscity value and validate.

If I understand correctly you consider that somewhere in a blood flow a clot appears. What do you want to do : analyse how this clot moves or how this clot, adherent to the vessel wall, interacts with the blood flow in the vessel section not yet clotted ?

Do you consider the "device" to be some thing as a stent ? or is it an "obstacle" to sense the presence of the clot ?

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