Lagrangian coherent structures (LCS) are mathematical constructs used to predict the dynamics of fluid flows, from ocean currents to turbulent clouds on other planets. Arezoo Ardekani discovered that LCSs can also be applied to viscoelastic flows. Credit: NASA/JPL-Caltech/SwRI/MSSS
Fluid dynamics researchers use many techniques to study turbulent flows like ocean currents, or the swirling atmosphere of other planets. Arezoo Adrekani’s team has discovered that a mathematical construct used in these fields provides valuable information about stress in complex flow geometries.
Ardekani, a Purdue University professor of mechanical engineering, studies complex flows: from the transport processes related to biopharmaceuticals, to the behavior of microorganisms around an oil spill. “Newtonian fluids like water are simple to understand, because they have no microstructure,” she said. “But complex fluids have macromolecules that stretch and relax, and that changes many properties of the fluid, leading to very exciting fluid dynamics.”
Viscoelastic flows occur frequently in nature, in biomedical settings, and in industrial applications—such as solutions used in groundwater remediation. “When groundwater becomes contaminated, remediators use certain polymer-based solutions to disperse chemicals designed to break down the contaminants,” Ardekani said. “But what type of polymer should they use, how much, and where should they inject it? The only way to answer those questions is by understanding the behavior of these flows, which comes down to measuring stresses.”
Currently, the only way to quantify the stresses of polymeric fluids is a technique called birefringence, which measure specific optical properties of the fluid. But it’s very difficult to perform, often inaccurate, and…
2023-01-27 15:36:14 A new way to identify stresses in complex fluids
Article from phys.org In recent years, researchers have made great strides in developing a new way to evaluate the stresses of complex fluids. By understanding how the stress of a fluid changes in the presence of external forces and over time, scientists are able to gain valuable insight into the properties of those fluids, which can have significant implications for technological advancements and engineering processes.
Using an innovative technique known as “Rheological Stress Estimation Using Differential Equations” (RSEDE), researchers have managed to create a system that can identify stresses in complex fluids without disrupting their natural internal balance. This system is based on the use of a closed-loop feedback control system, which analogously follows the motion of the fluid in a given environment. As the system is repeatedly exposed to different stimuli, the stress of the fluid is mapped and recorded, providing a unique analysis of how it responds.
In addition to improving our understanding of the stress behavior in complex fluids, this groundbreaking method has a wide range of practical applications. For example, engineers and researchers can use RSEDE to identify and analyze different fluid systems and materials, helping to develop more efficient and reliable engineering design models. Additionally, this technique can be applied to measure how different drugs interact with the body by simulating how they are broken down in the body’s physiological environment.
Ultimately, the development of RSEDE is an exciting breakthrough in the field of fluid mechanics, opening up a new wave of research. With further studies and experiments, this innovative system may be used to gain a deeper understanding of stress behaviors in complex fluids and the practical applications for engineering and medicine.