CM4650 Polymer Rheology
1. (20 points) (modified 4.3) Using Matlab, plot arrow plots of
steady shear and steady uniaxial extensional flow. Detailed
instructions are at this
link.
2. (10 points) 4.7 (calculate three invariants for steady
elongational flow)
3. (10 points) A key reason that shear flow was chosen as a
standard flow is that in the shear coordinate system (1=flow direction,
2=gradient direction, 3=neutral direction), t31=t32=t23=t13=0. How were
we able to prove that these coefficients of stress are zero for this
sysem? Just explain in a few sentences.
4. (10 points) For a Newtonian, incompressible fluid subjected to
steady shear flow, what is the predicted stress tensor?
(Hint: start with the velocity field; substitute it into the
constitutive equation and calculate the stress tensor).
5. (10 points) For a Newtonian, incompressible fluid subjected to
steady uniaxial elongational flow, what is the predicted stress tensor?
6. (30
points) 4.14 (follow points in shear, elongation) Note this is a 30 point question. Hint:
review discussion on page 111 for shear and on page 118 for elongation.
Extra
exercises for those who would like more math practice
1. (0 points) Beginning with equation 3.170 on page 86 of the text,
derive the pressure distribution (equation 3.177), the velocity
distribution (equation 3.178), and the flow rate per unit width
(equation 3.181) for Poiseuille flow in a slit.
2. (0 points) Beginning with equation 7.85 of the text and using
equation 7.91, calcluate the flow rate for the flow discussed, which is
given in equation 7.92.
3. (0 points) For Poiseuille flow in a tube of a Newtonian fluid
(section 3.5.3), calculate the total force on the walls of the
tube. Hint: you need to write the total force as a stress
times an area and then integrate. Does your answer make sense?