Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
bingham papanastasiou pipe
Posted 22.04.2016, 05:25 GMT-4 0 Replies
Please login with a confirmed email address before reporting spam
I'm currently working on a 3D model of a pipe, using the Bingham model (with the Papanastasiou correction). According to it, the viscosity can be written like it follows:
n = np + tau0*(1-exp(-m*gamapoint))/gamapoint
n - viscosity
np - dynamic viscosity
m - factor that determines whether the model is more similar to the newtonian solution (when m is 0) or to the Bingham solution ( when m tends to infinite). In this case, I've imposed m = 10000 to be able to compare results with the Bingham theory.
tau0 - yield shear stresss
gamapoint - shear rate
In COMSOL, I've inserted the equation by specifying the values as parameters and by writing the shear rate with the internal variable "spf.sr". However, the comparison between the theorical maximum speed and the value provided by the software shows a big difference between results.
VISCOSITY EQUATION WRITTEN IN COMSOL:
n = np + tau0*(1-exp(-m*spf.sr[s]))/spf.sr
THEORICAL EQUATION FOR THE BINGHAM VELOCITY PROFILE:
vz (r) = P*(R^2 - r^2)/(4*np*L) + Tau0*(R - r)/np
L - length of the pipe
R - radius of the pipe
Could someone help me here, telling me whether I've correcty implemented the model or if I've made a mistake somewhere?
Thank you in advance!
Hello Hanna Freitas
Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.
If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.