Ewoldt Research Group
I am helping develop a new experimental setup inspired by prior yield-stress fluid drop-impact work. The goal is to make drop release more repeatable with servo actuation, compare ways to measure how much fluid passes through a permeable mesh, and develop patterned fiberglass composites using heat-cured gels.
Research Area
Yield-stress fluids
Materials
Mesh composites
Current Focus
Controlled deposition
Research Context
The reference work examined yield-stress fluids impacting periodic meshes and perforated sheets, using drop mass, impact speed, fluid concentration, and mesh geometry to map when material transmitted through the mesh or remained captured by it. The new setup keeps that physical question but shifts attention toward mechanism design and repeatable release control.
Blackwell's dissertation studied how yield-stress fluid drops behave when they impact permeable meshes. Depending on drop energy, material rheology, and mesh geometry, the fluid could either adhere to the mesh, pass through it, or split into smaller transmitted droplets.
The current work keeps the core question: how much fluid is retained by the mesh versus transmitted through it, and how do repeatable drop conditions change that balance?
Instead of manually opening a dropper or release mechanism, the new setup is being designed around servo actuation so drop release can be controlled more repeatably and eventually tuned through timing, angle, or opening profile.
The servo system is still being designed, so the current engineering problem is not only whether the experiment works, but how to make the release motion consistent, cleanable, adjustable, and gentle enough to avoid changing the drop before impact.
Designing a servo-driven dropper mechanism that can open repeatably without disturbing the fluid before release.
Thinking through fixture geometry so the drop path, mesh location, and collection region stay aligned between trials.
Leaving room in the design for calibration, cleaning, and quick changes to the dropper or mesh hardware.
Connecting the mechanical release design to the larger experimental goal: controlled impact conditions and trustworthy transmitted-fluid measurements.
Composite Development
Alongside the drop-impact apparatus, I am developing a fiberglass-based composite material using a gel 3D printer. Different heat-cured gels are deposited in controlled patterns across the fiberglass mesh, creating a way to study how material choice and printed geometry change the behavior of the combined structure.
Deposit
Use the gel printer to place repeatable patterns onto the mesh.
Cure
Heat-cure different gel formulations to form the composite.
Compare
Evaluate how pattern and material choices affect the finished structure.
Measurement Strategy
The dissertation used mass collected below the mesh as a direct measurement of transmittance. In this version, several collection strategies are still under consideration because the measurement method needs to work with the fluid, mesh, fixture geometry, and available imaging or weighing tools.
One concept is to capture transmitted fluid in a sponge-like collector and use micro-CT scanning to estimate how much fluid entered the porous volume. This could give spatial information, but it adds scan setup, segmentation, and material-contrast challenges.
A simpler path is to collect the transmitted fluid and measure mass before and after the event. This is easier to validate and compare across trials, but the collection setup has to avoid losses from splash, residue, evaporation, or fluid left on fixture surfaces.
A likely design direction is to use weighing as the primary quantitative metric while keeping micro-CT or another imaging method as a possible secondary check when the distribution inside a collector matters.
What I Am Learning
This project is forcing the mechanical design and measurement plan to develop together. A clean servo mechanism is only useful if it improves repeatability, and a measurement method is only useful if it captures transmitted fluid without adding a larger source of uncertainty.