|Range of values|
|Range of values|
|Units:||Meters per second (m/s)|
|Range of values|
|Units:||Newtons per meter-squared (N/m2)|
This dataset presents observations of along-tank flow velocity at times surrounding incipient motion and to the shear stress associated with the given aSOA, for the same time period, derived from the along-tank flow velocity and individual aSOA characteristics of diameter and density. Along-tank flow velocities were collected by a single Vectrino acoustic Doppler profiler during a 2014 USGS small-oscillatory flow tunnel experiment conducted at the Naval Research Laboratory (NRL), Stennis Space Center, Mississippi. The information contained within the text files is needed to capture flow velocity at time of incipient motion, under ideal conditions, and to test shear stress-based incipient motion parameterizations. This dataset contains tabular digital data, in text files, of flow velocities in a small-oscillatory flow tunnel from the false-floor experiment, and shear stress derived from observed flow velocity. Each text file name ends with a three-character alpha-numeric aSOA identifier (aSOA ID). The first character (a number) refers to the aSOA’s size class, the second character (a letter) refers to the shape, and the third character (a number) refers to the unique aSOA of a given size class and shape (see Dalyander et al. (2015)). Videos of tank observations, which provide additional information about aSOA incipient motion, were also collected during each experiment (see 2017-309_DD_FF_video.zip) and are included in this data release).
First, velocities were passed through a MATLAB built-in one dimensional smoothing filter (filter.m) with a window size of ten. Second, the difference was taken between the raw and smoothed time series and the standard deviation of that difference was calculated. Third, points with a difference greater than three times the standard deviation were identified, and replaced with the smoothed signal value at the same time. The first, second, and third, steps were then repeated three times, with the previously de-spiked signal replacing the input each time, which produced final, quality controlled, de-spiked and smoothed de-spiked time series of velocities.De-spiked and smoothed de-spiked records of 3D velocity data, time, and depth information were re-saved in MATLAB readable ‘.mat’ files. De-spiked and smoothed de-spiked velocity data were treated with an additional quality control step.
A measure of signal quality, called Correlation, was recorded by the Vectrino profiler along with the raw data. Correlation is the measure of the data correlation as returned by each of the three acoustic beams of the profiler. Time points with correlation less than 70% are replaced in the record with non-number (NaN) values.Quality controlled records of de-spiked and smoothed de-spiked velocity were saved in MATLAB readable ‘.mat’ files. Person who carried out this activity:
Are there legal restrictions on access or use of the data?
Use_Constraints:Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. Please recognize the U.S. Geological Survey as the originator of the dataset.
This digital publication was prepared by an agency of the United States Government. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, nor shall the act of distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the data described and (or) contained herein. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
|Data format:||The WinZip (version 14.0) file provides flow velocity and shear stress data collected during small-oscillatory flow tunnel laboratory experiments at the Naval Research Laboratory, Stennis Space Center, Stennis Mississippi and the associated metadata. in format TXT (version 1) text file Size: 0.356|
This zip file contains data available in text file format (txt). The user must have software capable of reading text file format (txt) to use these data.