Vertical flows interacting with solid bodies occur frequently in nature and systems ranging from biochemistry to oceanography. However, they have not been studied in as much depth as the related problem of horizontal flows. This presentation will explain the application of the volume penalty method to model a two-dimensional cylindrical object moving through an unstratified fluid in order to gain understanding of vertical flows. We use the Dedalus numerical solver to solve our dimensionless system of differential equations. We find that the volume penalty method works effectively, giving the familiar wake structures (including steady wakes and von Karman vortex sheets) expected for circular cylinders. We also see that elongated cylinders exhibit the von Karman vortex street pattern for Re > 500 and that the drag for the elongated cylinders is significantly lower than that of cylinders.

Polymer Electrolyte Membranes (PEMs), are used in energy harvesting applications. This phenomenon is possible due to mechanoelectrical transduction, in which the deformation of material can generate electrical energy. Previous research focused on the impact different cation types have on the mechanical response and other characteristics. In previous studies, a higher response was discovered with the manipulation of the ionic valency and size ratio of the dissociated cations. The same investigation also estimated that the cation valency and size ratio directly correlates with the mechanoelectrical energy. This relationship dictates if the cation valency and size ratio increase the mechanoelectrical energy will also increase. Throughout the experiments, ionic liquid crystals elastomers (iLCEs) using various metal salts will be studied. Organic transistors will be created, by preparing mixtures and sandwiched cells with various alignment layers. These elastomers will be made using ultraviolet (UV) irradiation to induce cross-linking. The material of the iLCEs will be (M1+M2+photo.+ metal salts as ionic liquid ) and after preparing the mixture cross link at the right temperature the PEDOT: PSS coating will be applied to both sides.

Per- and poly-fluoroalkyl substances (PFAS) are artificially created chemicals that pose risks to the environment and human health. PFAS are persistent, bioaccumulative, and can be found everywhere in the environment, including water, contaminating our already limited water sources. PFAS are manufactured by replacing the hydrogen atom on a carbon chain with a fluorine atom. The carbon-fluorine bonds of PFAS are strong, making it challenging to degrade or treat, which usually involves costly processes such as thermal distraction. The most common and effective treatment for PFAS is granulated activated carbon (GAC). Even though GAC is economical, it becomes an unsustainable treatment due to its quick breakthrough of PFAS. In this project, we developed a cost-efficient and regenerative novel absorbent to remove PFAS from contaminated water. A critical part of the study is the molecular and surface characterization of the adsorption properties, kinetics, and strength. We use streaming zeta potential, contact angle measurements, and quartz crystal microbalance with dissipation to characterize the material and correlate its properties with adsorption performance.

Refractory high entropy alloys (RHEAs) are a novel class of materials that not only feature the high-temperature capabilities of refractory metals but also exhibit high-temperature strength unparallel to conventional commercial alloys. Although high strengths have been recorded at high temperatures, little has been known about the idiosyncrasies of diffusion in these materials that ultimately lead to their microstructural stability and idiomatic mechanical performance. Here, we simulate high-temperature conditions to analyze the characteristics of vacancy diffusion in the solid solution body-centered cubic (bcc) NbMoTaW RHEA using molecular dynamics simulations. Considering the significant lattice distortion that a multi-component alloy will experience at high temperatures, the vacancy location was determined by sorting through significant deviations of an average coordinate system from previous time steps. The mean-squared displacement of the vacancy migration through the system was then recorded to analyze the characteristic behavior of diffusion migration in this RHEA. Discrepancies from the typical linear displacement of atomic diffusion were then studied for lattice entrapment and lattice barriers. The implications of studying vacancy diffusion in this alloy ultimately allow for a better understanding of the creep mechanism and irradiative resistance that occurs within HEAs. Like most modern alloys, HEAs can be approached with a mechanism-based design that is engineered to exhibit certain strengthening mechanisms that can improve the functionality of the material in harsh environments.