DOI: 10.5281/zenodo.15132856
title: Combined Flow Experiments Conducted at the University of Texas, 2018

description: This is the file-processing scripts required to generate meaningful figures for topography, velocity, and derived values.

How to use these scriptsThere aren't any particularly unusual packages used in this analysis, but the key requirements are:numpyscipypandasmatplotlibseabornjupyteripymplThe parent utility file is in notebooks/utils_combined_flows.py and should be accessible through relative imports.The analysis of the data in the data/ directory is all generated through the Jupyter Notebooks.

Loading the data

Each plotting file, adp, adv, and topo, has a parent function that combs through the data/ directory and creates a top-level pandas dataframe that is used for plotting, analysis etc.

Experimental Description

From Smith et al 2019 (http://dx.doi.org/10.2110/jsr.2019.43)

Experimental flows were modeled in an open channel flume in the Experimental Sedimentology Laboratory at the Jackson School of Geosciences, The University of Texas at Austin. The flume is 11.00 m long, 0.61 m wide, 1.22 m deep and contains a ramp within it. Starting at the flume’s upstream end (0 m), the ramp is a horizontal surface from 0–1.24 m with the top of the ramp 1.01 m above the base of the flume. At 1.24 m begins a 5 m long ramp at a slope of 9°, leveling out to a 2.35 m horizontal plane that sits 0.06 m above the flume base. Whereas the overall slope of the ramp is constructed at 9°, one of the plates has an unintended, slightly lower slope (7°) from 4.88 to 6.00 m. The ramp is constructed of 0.02 m thick plexiglass plates, overlain with a lightly textured, 3 mm thick, rubber mat creating bed roughness. Beyond the experimental domain there is a sump from 10.00 m to 11.00 m, with an added depth of 0.73 m beneath the flume bottom that has a drain. In this box a standpipe exists to maintain a constant water depth of 1.15 m above the true flume bed during experimental flows.

The wave field in the tank is generated with a 2’ X 4’ plexiglass paddle fixed on a horizontal metal bar attached to a motorized wheel. A foam mat in the upstream end of the flume reduces reflections off the back wall. The wave maker produces waves with a 0.013 m amplitude, an approximate 3 m wavelength, and a period of 1.4 s.

For each flow, 900 l of water is mixed with 113.4 kg of 200 mesh quartz silt (D50=30 microns) in a 1000 l reservoir creating a 994 l mixture of 9.4% percent quartz silt concentration by volume. This mixture is pumped to a constant head tank feeding the flume through a 2 inch diameter PVC pipe flush with the ramp. For the duration of each flow, augurs continuously mix the sediment and water in both the reservoir and head tank.

An acoustic Doppler velocimeter (ADV) measures flow velocity at the centerline of the flume at 8.31 m from the inlet. The ADV measures the flow in 2 mm bins between 3 mm and 73 mm above the bed, at a frequency of 10 Hz. A Keyence laser topography scanner (LTS) on a moveable carriage measures centerline elevation from 8.03 m to 4.73 m. An acoustic Doppler profiler (ADP) mounted to the front of the carriage collects velocity measurements at 4 or 8 Hz, depending on the experiment, over the entire water column, excluding a blanking distance of 10 cm. The ADP data is collected in 2.5 and 3 cm vertical bins.

The primary variables are the presence or absence of a wave field, the inlet discharge of the current (either 1.25 l/s or 0.6 l/s), and the position of the inlet in the tank. All of these are used to test the relative effects of a wave field on a current.