Bulletin of the American Physical Society
Joint Fall 2017 Meeting of the Texas Section of the APS, Texas Section of the AAPT, and Zone 13 of the Society of Physics Students
Volume 62, Number 16
Friday–Saturday, October 20–21, 2017; The University of Texas at Dallas, Richardson, Texas
Session P6: Environmental Physics |
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Chair: Sally Hicks, University of Dallas Room: DGAC 1.135 |
Saturday, October 21, 2017 3:45PM - 3:57PM |
P6.00001: DSMC Simulations of High Mach Number Taylor-Couette Flow Dr. Sahadev Pradhan The main focus of this work is to characterise the Taylor-Couette flow of an ideal gas between two coaxial cylinders at Mach number \textit{Ma }$=$\textit{ (U\textunderscore w / }$\backslash $\textit{sqrt\textbraceleft kb T\textunderscore w / m\textbraceright )}in the range 0.01 \textless Ma \textless , and Knudsen number \textit{Kn }$=$\textit{ (1 / (}$\backslash $\textit{sqrt\textbraceleft 2\textbraceright }$\backslash $\textit{pi d\textasciicircum 2 n\textunderscore d (r\textunderscore 2 - r\textunderscore 1))) }in the range 0.001 \textless Kn \textless , using two-dimensional (2D) direct simulation Monte Carlo (DSMC) simulations. Here, \textit{r\textunderscore 1}and \textit{r\textunderscore 2}are the radius of inner and outer cylinder respectively, \textit{U\textunderscore w}is the circumferential wall velocity of the inner cylinder, \textit{T\textunderscore w}is the isothermal wall temperature, \textit{n\textunderscore d}is the number density of the gas molecules, $m$and $d$ are the molecular mass and diameter, and \textit{kb}is the Boltzmann constant. The cylindrical surfaces are specified as being diffusely reflecting with the thermal accommodation coefficient equal to one. In the present analysis of high Mach number compressible Taylor-Couette flow using DSMC method, wall slip in the temperature and the velocities are found to be significant. Slip occurs because the temperature/velocity of the molecules incident on the wall could be very different from that of the wall, even though the temperature/velocity of the reflected molecules is equal to that of the wall. Due to the high surface speed of the inner cylinder, significant heating of the gas is taking place. The gas temperature increases until the heat transfer to the surface equals the work done in moving the surface. The highest temperature is obtained near the moving surface of the inner cylinder at a radius of about (1.26 r\textunderscore 1). [Preview Abstract] |
Saturday, October 21, 2017 3:57PM - 4:09PM |
P6.00002: Shallow Soil Temperature Tracing Probe Calibration and Comparison to Thermal Models Laura Raines, Eddie Holik, James Ward, Emmett Spooner, David Kennedy Local soils in Tom Green county have no data relating to thermal gradients until now. A Hobo U23, which is to be calibrated, is currently being used to extract temperate data. The U23 sensors are wrapped around a 0.47 cm dowel rod inside a PVC pipe. The PVC pipe is then placed inside a galvanized steel pipe, which is driven 15.24 cm into the ground. Sensors are placed 2.5 cm and 10.16 cm in the ground. Over the course of 50 minutes, the sensors track the temperature as water infiltrates into the ground. These tests are being conducted on clay soils which were destroyed by brine water. Collected temperature data will be turned into thermal models. In all, the hopes of this research project are to be able to correlate temperature flux in various soils types to infiltration rates. [Preview Abstract] |
Saturday, October 21, 2017 4:09PM - 4:21PM |
P6.00003: Raman spectroscopic detection of bread mold Satyendra Kumar Mishra, Indra Ghirmire, Zack Liege, Dimitri Vornoninre, Alexei V. Sokolov, Ho Wai Howard Lee, Marlan O. Scully We present an application of Raman spectroscopy for the rapid characterization and identification of individual mold from several species of microfungi. We show the acquisition of unique Raman spectral signatures of bread mold under different growth conditions. The distinct emission peaks from the Raman spectra provide detailed insight into the overall chemical composition of the mold. We compare our results with those of clean bread and determine the detection limit of the mold measurements. In our study, we use 532 nm CW laser for non-resonant Raman scattering. The Raman spectra of mixture of 1 gram of bread mold in water filled in cuvette is recorded in reflection configuration. The presented results of mold detection will find applications in various fields such as agricultural photonic science, public health, biophotonics, and environmental microbiology. [Preview Abstract] |
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