Applied Fluids Laboratory

AFL Logo The Applied Fluids Laboratory (AppAFL) at Appalachian State investigates a broad range of topics related to the fluid mechanics of boundary layers and the coupling between fluids and terrestrial surfaces, as well as the development and application of instrumentation and analytical/numerical tools and methodologies.

More info: Dr. Chris Thaxton | website.

The AFL is currently adopting Machine Learning techniques for boundary layer applications - interested? The AFL is accepting new students! We are looking for students with programming experience (any of these: C, Java, XML, Fortran, Python, MATLAB, ArcGIS) and who are familiar with the Linux environment. Please contact Chris Thaxton.

AFL News

February 2024: Graduate student Adian Keaveney presented his work applying the OpenFOAM CFD to better quantifying the effects of seabed object shape on the production of turbulence which leads to enhanced sediment transport and object scour and burial at the 2024 Ocean Sciences conference in New Orleans, LA, USA, February 18-21, 2024.

December 2023: Undergraduate student Tess Mickey has been offered an NREIP fellowship at the Naval Resarch Labs in Washington, DC, for the summer of 2024. Congratulations Tess!

December 2023: The Applied Fluids Laboratory is a proud collaborator in the recently awarded NSF MRI program ($530,000.00). We will provide computational modeling support. Please see our article in Appalachian Today.

July 2023: The Appalachian Applied Fluids Laboratory (AppAFL) has been awarded a $350,000 contract with the U.S. Naval Research Laboratory's Ocean Sciences Division. The AppAFL team will work closely with colleagues at NRL and other universities to improve and develop computational models to better understand and predict seafloor dynamics in support of Naval operations. The five-year contract will provide summer and academic-year research assistantships to undergradute students in the applied physics program and graduate students in the engineering physics program, as well as substantial travel funds for students to conduct research at the U.S. Naval Research Laboratory's Stennis Space Center and attend international conferences. This year, the contract is supplemented by two additional student summer fellowships through the Naval Research Enterprise Internship Program.

May 2023: Undergraduate students Joshua McNeill and Nick Mencis are recipients of the 2023 NREIP (Naval Research Enterprise Internship Program) Internship at the Naval Research Laboratory, Stennis Space Center, Mississippi. The internship is administered by the American Society for Engineering Education (ASEE). It is nationally competitive, based on academic achievement, personal statements, recommendations, and career & research interests. It is a 10-week internship that provides stipends ranging from $7000 to $11.000. Appalachian's former NREIP awardees include Tomas Romero and Josh McNeill (2022), Jon Tate and Brandon Schwartz (2021/2020), Quinlin Riggs (2018), and Kevin Holway (2012). Joshua and Nick will be working with the Seafloor Sciences division.

The AppAFL student team, December, 2023.

From left to right: Adian Keaveney (Graduate student - CFD simulations), Nick Mencis (Graduate student - ML development), Josh McNeill (Graduate student - Team lead), Dr. Chris Thaxton, Tess Mickey (Undergraduate student - HYSPLIT/AppalAIR).

Recent Dissemination Products:

Engineering Physics graduate student Adian Keaveney presented his work "

Modeling the Effects of Object Induced Turbulence Enhancement of Seafloor Object Scour and Burial

" at the Ocean Sciences Conference, New Orleans, LA; Nearshore Processes IX, Poster Hall, First Floor (NOLACC), CP34A-1855, Wednesday, 21 February 2024

Engineering Physics graduate students Joshua McNeill and Nick Mencis (along with Tomas Romero, Travis Taylor, and Brynn Welch ) presented their poster "Development of a Regional Seafloor Object Scour and Burial Model in Support of U.S. Naval Operations" at the App State Office of Student Research Celebration of Student Research and Creative Endeavors on April 19, 2023.

Math graduate student Travis Taylor (Co-Authors: Nick Mencis, Joshua McNeill, Tomas Romero, and Brynn Welch) presented their poster "Modeling the Effects of Object-Induced Turbulence Enhancement on a Seafloor Object Scour and Burial" at the App State Office of Student Research Celebration of Student Researchand Creative Endeavors on April 19, 2023.

Graduate student Matt Phillips (Engineering Physics) and undergraduate students Joshua McNeill and Tomas Romero presented their poster "A Real-time Seafloor Object Scour and Burial Model: Revising the DMBP" at the App State Office of Student Research Celebration of Student Research and Creative Endeavors on April 21, 2022.

Graduate student Jacob Greenfield is 1st author of a peer-reviewed paper "Greenfield, J. and C.S. Thaxton. (2022).' Data Acquisition and Logging System for a Drone-mounted Atmospheric Sensor Suite, SoutheastCon 2022, 2022, pp. 178-183, DOI: 10.1109/SoutheastCon48659.2022.9764113." He presented his work in April 2022.

Our group's paper "Thaxton & Calantoni, 2022. Modeling the Combined Parameter for Incipient Motion from the Force Balance on a Single Proud Grain" has been in the European Journal of Mechanics / B Fluids. https://doi.org/10.1016/j.euromechflu.2022.02.010


GES undergraduate Carly Bauer [LEFT], going over her poster on the correlations between hurricane landfalls and tides at the Student Research and Creative Endeavors event on April 21, 2022.	Undergraduates Tomas Romero [LEFT] and Joshua McNeill [RIGHT], and graduate student Matt Phillips [CENTER] present their work on mine burial modeling at the Student Research and Creative Endeavors event on April 21, 2022. Romero and McNeill are supported by the 2022 NREIP fellowship, NRL.	Graduate student Jacob Greenfield [LEFT] and Dr. Bob Swarthout [RIGHT] attach the data acquisition system to the drone.

AFL Information

WRF run request - Our WRF runs are now automated! If you wish for us to run WRF in research or operational mode, please provide the requested information. We will respond within 48 hours.

Related Courses (Thaxton): PHY3150 Atmospheric Physics (text); PHY 5500 Fluid Mechanics (text).

Related Programs: Atmospheric Science Minor

Physical Resources:

Alienware Aurora R13 w/ RTX 3090: Research 1 (Linux/WIndows). MATLAB, OpenFOAM CFD and supporting software, WRF, Python environment, CUDA
Dell Precision 7960: Research 2 (Linux). OpenFOAM CFD with supporting software, HYSPLIT, WRF, CUDA
Dell Precision 5820 Tower XCTO: Instructional (Linux). MATLAB, COMSOL, ssh/sftp capability, various linux opensource apps. Supports PHY 3020, PHY 4020/5020, PHY 5550.
Dell T1700 : Research 3 (Linux). Code development.
2 x University-build All-in-one (Windows). Administrative, research support.
Electronics workstation, weather balloons and equipment, drone platform electronics.

Current Projects

The burial and transport of seabed objects.

Prediction of the burial and transport of objects resting on the seafloor has been a topic of interest for the Navy for some time. Established and widely accepted parametrized approaches have seen limited success, primarily due not only to the difficulty in parameterizing mean-field effects but also the cumulative effects of near-object scour dynamics, including during extended periods of low forcing energetics. Even under highly controlled laboratory conditions, most datasets show substantial variability in the rate of burial and the equilibrium burial depths for a wide range of object material variables and forcing conditions. We intend to improve existing object burial and transport models by (1.) applying state-of-the-art techniques in data analysis on existing field and experimental data and (2.) revising and refining the physics models based on current and emerging research. We want to tease out the sensitivity of the model for the various variables and refine the models to include these effects.

Optimizing planetary boundary and surface layer schemes in the WRF model and characterizing turbulence sourcing over the Southern Appalachians.

The Intergovernmental Panel on Climate Change (IPCC), in its latest report, states that climate change will likely lead to more intense and variable weather systems on regional and local scales. The Weather and Research Forecasting model (WRF), developed and supported by a collaborative managed by the National Center for Atmospheric Research (NCAR), is a well-established regional model used by thousands of scholars and forecasters serving in domestic and military capacities throughout the world. To improve the performance of WRF to meet emergent challenges, smaller-scale physical processes that have traditionally been parametrized out of necessity, such as planetary boundary layer (PBL) turbulence and mixing, now require marked improvements in parameterization schemes that are more finely tunable to specific local geographical and climatological conditions. The primary short-term goal of our research team is to optimize PBL parameterization schemes in WRF to better understand and most effectively represent the enhanced turbulence production and resulting dissipation that arises due to the complex terrain and relatively moist climate in the Southern Appalachians.

Theory for incipient motion in oscillatory flows.

In collaboration with the Naval Research Laboratory, we seek to develop a combined incipient motion formulation for better prediction of sediment mobilization under a range of oscillatory flows. The formulation is based on the role of the fluid shear stresses (e.g., Shields parameter) and pressure gradients (e.g., Sleath parameter; Foster et al., 2006) at the onset of sediment motion. Observations across a range of sediment size and density suggested that incipient motion was induced by the pressure gradients in flows with large accelerations, by the shear stresses in flows with small accelerations, and by the combined effects for intermediate flows. Direct numerical simulations were performed for one set of experiments involving acetate beads. The resulting hydrodynamics and turbulent characteristics were compared with the laboratory experiments. We attempt to close the problem with a theoretical investigation into the force balance on a single grain resting on the bed under prescribed monochromatic oscillatory forcing. The theoretical investigation combines formulae from a variety of sources including empirical and quasi-empirical relations to examine the incipient motion of particles across a wide range of conditions applicable in the marine environment.

Team Theses

Allen, M. Development and characterization of newest generation handheld sunphotometer for measurements of aerosol optical depth by citizen scientists, App State, 2023 (J. Sherman)

Jonaitis, J. Spatiotemporal Patterns of ENSO-Precipitation Relationships in the Tropical Andes of Southern Peru and Bolivia, App State, 2020 (B. Perry)

Archer, J.R. Computational fluid modeling of a variable angle fuel injector, App State, 2011 (C. Thaxton)

Penders, C. Determining mean grain size in high gradient streams with autocorrelation digital image processing, App State, 2010 (C. Thaxton)

Kelly, J. Experiments in bulk thermal sink capacities of unconsolidated material, App State, 2008 (C. Thaxton)

Jones, A. Integrated nearshore wave amplitude model for use on portable devices, App State, 2005 (C. Thaxton)

Peer-reviewed Publications (students in italics)

Thaxton, C.S., A. Keaveney, N. Mencis, J. McNeill (In preparation). Modeling the Effects of Object-Induced Resonant Turbulence Enhancement of Seafloor Object Scour and Burial

Thaxton, C.S. and J. McNeill . 2023. Technical Report: Overview of the Munitions Response Library- AppAFL Research Suite (MRL-ARS), BAA Number: N00173-19-S-BA01; 74-19-01, Naval Research Laboratory, Stennis Space Center, MS, US; Oct. 3, 2023

Thaxton, C.S. and J. Calantoni. 2022. Modeling the Combined Parameter for Incipient Motion from the Force Balance on a Single Proud Grain, European Journal of Mechanics - B/Fluids, Vol. 94 (July-August 2022), pp. 334-349, https://doi.org/10.1016/j.euromechflu.2022.02.010

Greenfield, J. and C.S. Thaxton. 2022. Data Acquisition and Logging System for a Drone-mounted Atmospheric Sensor Suite, SoutheastCon 2022, 2022, pp. 178-183, DOI: 10.1109/SoutheastCon48659.2022.9764113.

Jonaitis. J., L. Baker Perry, Peter T. Soulé, Christopher Thaxton, Marcos F. Andrade-Flores, Tania Ita Vargas, and Laura Ticona. 2020. Spatiotemporal Patterns of ENSO-Precipitation Relationships in the Tropical Andes of Southern Peru and Bolivia, International Journal of Climatology, 2021;41:4061–4076, https://doi.org/10.1002/joc.7058

Thaxton, C.S., W. P. Anderson, Jr., Chuanhui Gu, Borko Stosic, Tatijana Stosic. 2018 - Detrended fluctuation analysis and entropy-complexity causality analysis of temperatures in an urbanized mountain stream. Stoch Environ Res Risk Assess. https://doi.org/10.1007/s00477-017-1434-8

Holway, K, C.S. Thaxton, J. Calantoni. 2012. Application of a simple power-law for transport ratio with bimodal distributions of spherical grains under oscillatory forcing, Advances in Water Resources, 48: 47-54

Rice J.S., W.P. Anderson Jr., C.S. Thaxton. 2011. Urbanization influences on stream temperature behavior within low-discharge headwater streams, Hydrological Research Letters (5): 27-31.

Anderson, W.P. Jr., J.L. Anderson, C.S. Thaxton, C.M. Babyak. 2010. Changes in stream temperatures in response to restoration of groundwater discharge and solar heating in a culverted, urban stream, Journal of Hydrology, 393 (3-4): 309-320

Jones, A.F. and C.S. Thaxton. 2008. Integrated Nearshore Wave Amplitude Model for Use on Portable Devices, IEEE SouthestCON 2008, Peer-reviewed conference proceedings, IEEE, Huntsville, AL, 31-36, DOI 10.1109/SECON.2008.4494249

Calantoni, J. and C.S. Thaxton. 2007. Simple power-law for transport ratio with bimodal distributions of coarse sediments under waves. Journal of Geophysical Research, 113, C03003, doi:10.1029/2007JC004237\

Mitasova, H. Thaxton, C.S., Hofierka, J, McLaughlin, R., Moore, A., Mitas. L. 2007, Path sampling method for modeling overland water flow, sediment transport, and short term terrain evolution in Open Source GIS, Developments in Water Science, Volume 55, Part 2, 2004, Pages 1479-1490

Thaxton, C.S., C.M. Babyak, W. Anderson. J. L. Anderson, W.P. Benner III, J.A. Davis, and C.A. Penders. 2007. Baseline monitoring case study of a high-gradient, urbanized stream - Boone Creek, Boone, NC, 2007 Low Impact Development Conference Proceedings, ASCE. (peer-reviewed - American Society of Civil Engineers, March 2007)

Thaxton, C.S. and R.A. McLaughlin. 2005. Sediment Capture Effectiveness of Various Baffle Types in a Sediment Retention Pond, Transactions of the ASAE, 48(5): 1795-1802

Thaxton, C.S., Calantoni, J., McLaughlin, R.A. 2004. Hydrodynamic Assessment of Various Types of Baffles in a Sediment Detention Pond, Transactions of the ASAE, 47(3): 741-749.

Thaxton, C.S., Mitasova, H., Mitas, L., McLaughlin, R. 2004. Simulations of distributed watershed erosion, deposition, and terrain evolution using a path sampling Monte Carlo method, ASAE Annual International Meeting 2004; Ottawa, ON; Canada; 1 August 2004, Paper number 042101, 2004 ASAE Annual Meeting. (DOI: 10.13031/2013.16380) @2004.

Presentations

Thaxton, C.S., A. Keaveney, N. Mencis, J. McNeill. 2024. Modeling the Effects of Object-Induced Resonant Turbulence Enhancement of Seafloor Object Scour and Burial, 2024 Ocean Sciences (Accepted) Abstract# 1489616 , New Orleans, LA, Feb. 18-23, 2024

Thaxton, C.S., D. Frank-Gilchrist, and J. Calantoni, 2019. Phase-resolved Parameterization for Incipient Motion of Coarse Sand, Grains.THESIS-2019: The 4th symposium on two-phase modeling for sediment dynamics in geophysical flows, September 17-19, 2019; Newark, Delaware, USA

Thaxton, C.S., N. Sanford, and J. Langston, 2018. Modification of WRF/MPAS PBL Schemes for Northwest Flow Snow (NWFS) Events in the Southern Appalachians, A31K: Boundary Layer Processes and Turbulence, 2018 American Geophysical Union Fall Conference, Wednesday, December 12, 2018, Washington, DC, USA

Thaxton, C.S. and Q. Riggs, 2018. Analysis of seasonally-dependent bias in WRF PBL schemes for the southern Appalachian Mountains. P53 Model Evaluation, WRF/MPAS User's Workshop, NCAR, Boulder Colorado, June 13, 2018

Thaxton, C.S. 2018. Toward Improved Correlations between WRF Model and Remotely-sensed PBL Height Retrievals for the Southern Appalachian Mountains, Ad-Hoc Mixing Layer Height Working Group, April 11, 2018, UMBC (Instrumentation: Ground and Satellite, Modeling)

Thaxton, C. S., J.P. Sherman, I.A. Krintz, Q. Riggs, A. Scher, D. Ross, D. Schlesselman. 2017 AGU Fall Conf., "Optimizing Weather Research and Forecasting model parameterizations for boundary-layer turbulence production and dissipation over the Southern Appalachians," AGU EP43C-1896, New Orleans, LA. (Nov. 14, 2017).

Thaxton, C. S., D. Ross. 2017 WRF Workshop, "Preliminary evaluation of WRF physics options for the Southern Appalachian Mountains," P55 Model Evaluation, Boulder, CO. (June 14, 2017).

Thaxton, C. S., Frank, D., Calantoni, J. 2016 Ocean Sciences, "Lagrangian Measurements, Simulation, and Theory for Incipient Motion in Oscillatory Flows," AGU, New Orleans, LA. (February 25, 2016).

Thaxton, C. S., Frank, D., Calantoni, J., Simeonov, J., 2015 American Geophysical Union (AGU-Annual Meeting), "Lagrangian Measurements, Simulation, and Theory for Incipient Motion in Oscillatory Flows," AGU, San Francisco, CA. (December 2015).

Thaxton, C.S. 2015. Modeling granular flows in coastal applications, 5 Congreso de Fisica y Matematicas' Universidad de las Americas-Puebla, Cholula, Puebla, MX, April 9, 2015

Thaxton, C.S. and J. Calantoni. 2012. Modeling and experiments for sheet flow transport with bimodal size distributions (Control ID 1487689), AGU Fall Meeting, 3-7 December 2012, San Francisco, California.

Holway, K., C. S. Thaxton, J. Calantoni. 2010. Application of a simple power-law for transport ratio with bimodal distributions of spherical grains under oscillatory forcing, Symposium on Two-phase Modelling for Sediment Dynamics in Geophysical Flows, Paris, France, April 26-28, 2011,

Sheremet, A., J. Calantoni, and C.S. Thaxton. 2008. Towards predicting sheet flow sediment transport as a diffusive process. Eos. Trans. AGU 89(53), Fall Meet. Suppl., OS21E-1210.

Calantoni, J. and C. S. Thaxton. 2008. Simple power-law for transport ratio with bimodal distributions of coarse sediments under waves, Fourth Gordon Research Conference on Granular and Granular Fluid Flow on June 23, 2008, at Colby College in Waterville, ME

Thaxton, C.S. 2007. Thermal data acquisition and predictive modeling for urbanizing head-water streams in the Southern Appalachians, Invited Lecture, Naval Research Laboratories, Stennis Space Center, MS

Thaxton, C.S., C. Penders, W. Anderson, J. Anderson, C. Babyak, W. Benner, III. 2007. Impacts of Urbanization on Headwater Streams of the New River: How Do We Bring Back the Trout?. 2007 New River Symposium, New River Biota II, May 31 - June 2, 2007, Radford University, Radford, VA.

Anderson, J.L., W.P. Anderson, Jr., C.S. Thaxton, and C.M. Babyak. 2007. Dynamics of episodic temperature variations in an urbanized, high-gradient stream. Paper No. 9-1 in Geological Society of America Abstracts with Programs, Vol. 39(2), p. 17. GSA Southeast Section Meeting, Savannah, GA.

Thaxton, C.S., C.M. Babyak, W. Anderson. J. L. Anderson, W.P. Benner III, J.A. Davis, and C.A. Penders. 2007. Baseline monitoring case study of a high-gradient, urbanized stream - Boone Creek, Boone, NC, 2007 Low Impact Development Conference Proceedings, ASCE. (peer-reviewed - American Society of Civil Engineers, March 2007)

Thaxton, C.S. 2006. Path sampling Monte Carlo method for watershed-scale terrain evolution in GRASS GIS. Invited lecture, Naval Research Laboratory, Stennis Space Center, MS. May 14, 2006.

Thaxton, C.S. & J. Calantoni. 2006. Vertical sorting and preferential transport in sheet flow with bimodal size distributions of sediment, Coastal Engineering, 2006: Proceedings of the 30th International Conference on Coastal Engineering (ICCE 2006) 3-8 September, Ed. Jane McKee Smith, World Scientific Publishing, Hackensack, NJ. Vol. 3, pp. 3056-3065.

Penders, C., W. Benner, J. Anderson, C. Thaxton, C. Babyak, W. Anderson. 2006. Case Study: Boone Creek Monitoring Project - Boone, NC, State of North Carolina Undergraduate Research and Creativity Symposium, November 18, 2006, Raleigh, NC.

Thaxton, C.S. and J. Calantoni. 2006. Simple Power Law for Transport Ratio with Bimodal Distribution of Coarse Sediment, N8.00006, 2006 American Physical Society March Meeting, Baltimore, MD

Mitasova, H., C. Thaxton, J. Hofierka, R. McLaughlin, A. Moore, L. Mitas. 2005. Path sampling method for modeling overland water flow, sediment transport, and short-term terrain evolution in Open Source GIS. In: C.T. Miller, M.W. Farthing, V.G. Gray, G.F. Pinder eds., Proceedings of the XVth International Conference on Computational Methods in Water Resources (CMWR-XV), June 13-17, 2004, Chapel Hill, NC, USA, Elsevier, pp. 1479-1490.

Thaxton, C.S., Mitasova, H., Mitas, L., McLaughlin, R.A., Landscape-scale Grain Size-Dependent Simulations of Erosion and Deposition Using a Path Sampling Method, 204(SW-21), 2004 ASAE/CSAE Annual International Meeting, Ottawa, Canada August 1-4, 2004

McLaughlin, R.A., Thaxton, C.S., Optimal Hydraulic Permeability of Composite Geotextiles as Baffles in a Sedimentation Basin, 218(SW-224), 2004 ASAE/CSAE Annual International Meeting, Ottawa, Canada August 1-4, 2004

Thaxton, C.S. 2004. Path Sampling Monte Carlo Method for Modeling Sediment Transport Processes Over Complex Terrain. 2004. N.C. Sectional Meeting of the American Association of Physics Teachers, Meredith College, Raleigh, NC, 2004.