Kameko Landry '19
Summer Research Scholar with David Harbor, Summer 2018
This summer I continued research for my honors thesis with Professor Dave Harbor. My goal for the summer portion of my research was to test and implement high-accuracy pressure sensors directly into the plexiglass flume. Understanding the mechanism for plucking is necessary to model river incision going forward. We propose three hypotheses for how plucking is initiated in rapidly varied flow. The first two hypotheses: change in head and coherent flow structures along the bed, are driven by the hydraulic jump. The third hypothesis: pressure pulse transmission, is aided by upstream steps but is not studied extensively. There has been some previous research on changes in pressure in the sub-bedrock crack network. For that research, submersible pressure sensors were used in the flume, and the modeled bedrock was placed on top of the sensors imbedded in boards. By inserting pressure sensors directly into the floor of the flume, there is minimal disruption to our test site. We hoped to get accurate pressure readings so we can identify any correlation between plucking events and changes in pressure.
First I researched pressure transducers capable of reading 0-1 Psi. This proved to be a challenge since most industrial pressure sensors are calibrated to measure up to 15-3,000 Psi. After finding one which met all the criteria, it was time to drill into the flume. Plexiglass is notorious for cracking and splitting when it is drilled into. To combat this, I researched different types of drill bits that could give us ideal results. One method I tried was to sharpen the drill bit to a 90-degree angle using a pedestal grinder. Although exciting, it proved to give no significant results. Finally, Dave found an extended bit and I was able to successfully drill into the flume.
I programmed an Arduino (an open-source electronics platform) to process the data being collected by the pressure sensor. The Arduino is connected to a desktop so that we can see the data being recorded in real-time. The goal of my thesis is to get six of these pressure sensors mounted into the flume so that we can see pressure changes along the whole test bed when plucking occurs. The pressure sensors can also be used with the dye-dispensing system that Ryan Monson created this summer. This will allow us to look at two hypotheses, pressure changes and coherent flow structures along the bed, for the initiation of plucking during a single experiment.