@misc{9231205,
  abstract     = {{Asymmetric flow field flow fractionation (AF4) is a prominent separation technique used to separate larger particles such as lipid nanoparticles or macromolecular polymers. When combined with Small angle neutron scattering (SANS), this provides the possibility to probe the inner structure of the particles, instead of only probing the general size of the particles. However, putting the SANS measurement in-line as a continuous measurement provides some challenges. Since the beam is bigger at a lower flux than for example X-rays, the geometry plays an important role in affecting both residence time, peak broadening and signal height. Using computational fluid dynamics, it is possible to predict the performance of multiple possible geometries digitally before manufacturing a costly physical cell.

Using Ansys Fluent, a pipeline was created which creates geometries, calculates the flow pattern and then uses either a discrete phase modeling (DPM) to track particles through the fluid cell or a transient species transport model to simulate a tracer concentration. Using these particle tracks, a simulated fractogram was then computed from which full width at half maximum (FWHM) as well as peak height was calculated. These metrics were then compared between three different series of geometries: a teardrop shaped cell used previously in physical experiments, a rectangular cell with parametrized transitions, as well as a serpentine flow cell with constant flow width.

The results show that the DPM model and the species model give highly similar results, verifying the use of the DPM model. Furthermore it shows some tradeoffs between the beam area covered and its effect on peak width and height.}},
  author       = {{Tamm, Witko}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Development of a measurement cell for AF4 SANS}},
  year         = {{2026}},
}