1. Laura Schmidt (Nagel lab) Physics 335, 10 March 2004 Selective withdrawal with a non-Newtonian fluid A bit of review… The process: withdrawing fluid through a pipette positioned above a two-fluid interface. Much work has already been done to characterize the interface profiles for Newtonian, but not non-Newtonian fluids. Question: what will happen if the lower fluid has a polymer in it?

2. Overview of project direction  Build and assemble apparatus  Make adjustments to apparatus to address problems and calibrate pump (expect completion by March 19)  Obtain data for hump/spout surfaces and transition points for water and oil and check for consistency with previous experiments (expect completion by April 2)  Add polymer to water and to see non-Newtonian effects. This system can then be directly compared to previous set-up with water/oil.

3. recycle container pump camera main tank encoder

4. vent filter, keeps the air pressure in tank at P ATM Two tubes from recycle tank. This flow is governed by gravity, not the pump so two tubes makes the flow faster. acyrlic tank filled with oil and H 2 0 The “slider” holds the pipette and moves up and down along two steel rods. The height of the pipette is controlled by a fine-threaded screw (80 TPI)

5. Debugging the experiment 1.Camera- focus vs. zoom. The current lens doesn’t give enough magnification, but after adding the bellows for magnification, I can only get too large a photo. 2.Too many bubbles when spout forms. This may be because I didn’t let the tank settle long enough after pouring in the fluids. 3.Adjustments of light source for perfect photos. 4.Make a platform for the tank so the camera can sit level to the ground. Also, must calibrate the pump for the oil.

6. Preliminary photographs 1.5 mm A very thin thread is formed, probably ~10  m. -Notice bubbles beneath surface.

7. To compare with previous water/oil results, I will find the relation between S and Q. It was previously found to follow the power law, S u ~ Q 0.32. S u, the height of the orifice above the unperturbed surface at the transition from hump to spout. Q, the flow rate.