CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > General Forums > Main CFD Forum

Rheology Question

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 7, 2003, 04:12
Default Rheology Question
  #1
JamCam
Guest
 
Posts: n/a
Sorry, but this question is not related to CFD, but I know this forum can be very helpful. To calculate K, the consistency factor for Power Law fluids from shear stress (Dynes/cm2) and shear rate (sec-1) readings, you use this equation:

K = 100*shear stress @ 300rpm / shear rate @ 300 rpm^n

n = the Power Law exponent

This gives K in centipoise. I see many people use eq. cp or Pa.s^n. What are these units?! How can I convert centipoise to eq.cp or Pa.s^n

Any help gratefully appreciated!

JC
  Reply With Quote

Old   August 7, 2003, 05:47
Default Re: Rheology Question
  #2
Tom
Guest
 
Posts: n/a
Hi,

If you visit www.efluids.com you will find a Unit Conversion Calculator. Perhaps that is helpful.

Tom
  Reply With Quote

Old   August 7, 2003, 06:13
Default Re: Rheology Question
  #3
JamCam
Guest
 
Posts: n/a
Thanks for the reply, unfortunately I've tried many a conversion calculator, with no mention of eq. cp or Pa.s^n. I'm sursprised at the lack of information in books and on the web about this. I just need something that explains the difference to me!

JC
  Reply With Quote

Old   August 7, 2003, 06:46
Default Re: Rheology Question
  #4
Andreas
Guest
 
Posts: n/a
Hi Jam As far as I know, centipoise (cPs) is an obsolet unit for viscosity.

1 Pa*s = 1000 centipoise

Bye Andreas
  Reply With Quote

Old   August 7, 2003, 06:57
Default Re: Rheology Question
  #5
JamCam
Guest
 
Posts: n/a
Thanks,

I know centipoise is a bit obsolete, the preferred SI unit is indeed Pa.s (the same as N.s.m2 and kg.m.s).

It's when we're dealing with consistency factor K and flow behaviour index, n that eq.cp or Pa.s^n appears. It has something to do with this, but I don't know what!

For online conversion, you can't beat this site:

http://www.ex.ac.uk/cimt/dictunit/dictunit.htm

but there's no mention of what I'm after here!

JC
  Reply With Quote

Old   August 11, 2003, 08:01
Default Re: Rheology Question
  #6
Pete
Guest
 
Posts: n/a
You'll be surprised how much we use centipoise in industry!
  Reply With Quote

Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Unanswered question niklas OpenFOAM 2 July 31, 2013 16:03
Power law fluid question Wesley OpenFOAM Running, Solving & CFD 0 April 3, 2009 16:21
Poisson Solver question Suresh Main CFD Forum 3 August 12, 2005 04:37
CHANNEL FLOW: a question and a request Carlos Main CFD Forum 4 August 23, 2002 05:55
question K.L.Huang Siemens 1 March 29, 2000 04:57


All times are GMT -4. The time now is 09:57.