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Metrology

Flow metrology and rheology

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Displaying 1 - 25 of 184

Photopolymer Additive Manufacturing 2025 Workshop Report: Building a Unified Vision from Research to Regulation

June 10, 2026
Author(s)
Callie Higgins, Jason Killgore, Mike Idacavage, Vince Anewenter, Mickey Fortune, Gary Cohen, Perri Katzman, Jessica Hemond, Spencer Loveless, Michael Gould
The third biannual Photopolymer Additive Manufacturing Alliance Workshop was held on September 15-16, 2025, at the University of Colorado Boulder to continue its mission of advancing photopolymer additive manufacturing (PAM). Building on the 2023 PAMA

A Non-Intrusive Analytic Temperature Model for Rate-of-Rise-Based Gas Flow Standards

May 20, 2026
Author(s)
Aaron Johnson, Jodie Pope, Keith Gillis, John Wright, Christopher Crowley
Accurate measurement of low gas flows is essential in semiconductor manufacturing, where mass flow controllers (MFCs) regulate gas stoichiometry during etching and deposition. The Rate-of-Rise (RoR) method, widely used for MFC calibration, determines mass

Bilateral Airspeed Comparison (2-20 m/s) Using Three Transfer Standards

May 20, 2026
Author(s)
Christopher Crowley, Iosif Shinder, Joey Boyd, Fabio Costa, Samuel Araujo
A bilateral comparison of airspeed standards between NIST and Inmetro was carried out over the range 2 m/s to 20 m/s using three transfer standards: a Pitot tube, a 3D ultrasonic anemometer, and a laser Doppler anemometer (LDA). The instruments were

Ultra-low-speed anemometer calibrations in a bench-top wind tunnel

May 20, 2026
Author(s)
Christopher Crowley, Jeyadave Kumar, Iosif Shinder
Accurate calibration of anemometers at ultra-low airspeeds (i.e. speeds below 1 m/s) is essential for applications such as indoor airflow measurement, cleanroom monitoring, and environmental sensing. To address this need, the National Institute of

Estimating How Big: The Metric Estimation Game

July 30, 2025
Author(s)
Elizabeth Benham, Kristen Dill, Dinelka Jagoda, Maryanne Amanze, Yoon Thwel
The metric system (International System of Units, SI) is easy to use and learn. The Metric System Estimation Game is a fun, hands-on activity that helps participants become familiar with SI measurements by practicing estimation skills. During this activity

Rheology and Microstructural Behavior of Semidilute Suspensions of Semiflexible Rods across Five Decades of Shear Rate

February 18, 2025
Author(s)
Paul Salipante, Ryan Murphy, Steve Kuei, Jeffrey Fagan, Christopher Sims, Kathleen Weigandt, Steven Hudson
Rod-like particles are efficient rheology modifiers and are commonly found in a variety of biological and industrially relevant suspensions, from biofilaments to worm-like surfactant micelles. These suspensions display strong shear-thinning behavior, and

Calibrating laser Doppler anemometers utilizing an optical chopper

January 31, 2025
Author(s)
Christopher Crowley, Iosif Isaakovich Shinder, Michael R. Moldover, Joey Boyd, James Filla, Aaron Johnson
Laser Doppler anemometers (LDAs) use scattered light to determine velocity components of a flowing fluid. The operating principal of LDAs is simple conceptually; however, it is impractical to trace the LDA-determined velocities to the SI by characterizing

Two-fluid model for nonlinear flow of wormlike micelle solutions. II: Experiment

November 1, 2024
Author(s)
Paul Salipante, Michael Cromer, Steven D. Hudson
Applications often expose wormlike micelle solutions to a very wide range of shear and temperature conditions. The two-species model presented in Part I [Salipante et al., J. Rheol. 68 (2024)] describes the nonlinear rheology over a wide range of shear

Entanglement kinetics in polymer melts are chemically specific

July 3, 2024
Author(s)
Benjamin Dolata
We investigate the universality of entanglement kinetics in polymer melts. We compare predictions of a recently developed constitutive equation for disentanglement to molecular dynamics simulations of both united-atom polyethylene and Kremer-Grest models

Evaluating Models That Predict Epoxy Conversion Using Rheological Properties

April 15, 2024
Author(s)
Stian Romberg, Paul Roberts, Chad R. Snyder, Anthony Kotula
Simultaneous rheology and conversion measurements of neat and composite epoxy resins reveal that conventional models neither accurately nor fully describe the relationship between rheology and conversion. We find that models predicting thermoset conversion

Non-nulling Protocols for Fast, Accurate, 3-D Velocity Measurements in Stacks

July 28, 2023
Author(s)
Iosif Isaakovich Shinder, Aaron Johnson, James Filla, Vladimir B. Khromchenko, Michael R. Moldover, Joey Boyd, John D. Wright, John R. Stoup
We present protocols for making fast, accurate, 3-D velocity measurements in the stacks of coal-fired power plants. The measurements are traceable to internationally-recognized standards; therefore, they provide a rigorous basis for measuring and/or

Dynamic Measurement of Gas Flow using Acoustic Resonance Tracking

March 21, 2023
Author(s)
Jodie Gail Pope, Keith A. Gillis, James W. Schmidt
We measured gas flows exiting large, un-thermostated, gas-filled, pressure vessels by tracking the time-dependent pressure P(t) and resonance frequency fN(t) of an acoustic mode N of the gas remaining in each vessel. This is a proof-of-principle

Microfluidic techniques for mechanical measurements of biological samples

January 20, 2023
Author(s)
Paul Salipante
The use of microfluidics to make mechanical property measurements is increasingly common. Fabrication of microfluidic devices has enabled various types of flow control and sensor integration at micrometer length scales to interrogate biological materials

Gas Flow Standards and Their Uncertainty

December 12, 2022
Author(s)
John D. Wright, Aaron Johnson, Michael R. Moldover, Shin-ichi Nakao
We review diverse types of gas flow standards that are used to calibrate other gas flow meters. For each type of standard, we describe the principles of its operation and at least one hardware example. We identify the practical limits of the example's

SerialTrack: ScalE and Rotation Invariant Augmented Lagrangian Particle Tracking

September 19, 2022
Author(s)
Jin Yang, Yue Yin, Alexander Landauer, Selda Buyukozturk, Jing Zhang, Luke Summey, Alexander McGhee, Matthew Fu, John Dabiri, Christian Franck
We present a new particle tracking algorithm to accurately resolve large deformation and rotational motion fields, which takes advantage of both local and global particle tracking algorithms. We call this method the ScalE and Rotation Invariant Augmented

Overcoming Technological Barriers in Microfluidics: Leakage Testing

September 1, 2022
Author(s)
Vania Silverio, Suvajyoti Guha, Armelle Keiser, Rucha Natu, Darwin Reyes-Hernandez, Henne van Heeren, Nicolas Verplanck, Luke Herbertson
The miniaturization of laboratory procedures for Lab-on-Chip (LoC) devices and translation to various platforms such as single cell analysis or Organ-on-Chip (OoC) systems are revolutionizing the life sciences and biomedical fields. As a result
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