| To explore the dynamics of coherent structures (CS), we analyze direct numerical simulations (DNS) of two prototypical flows: vortex reconnection--a dynamically significant CS interaction and a polarized ring--an idealized CS.;The second study was prompted by the observation that most vortical structures in transitional and turbulent flows are partially polarized (i.e., vortex lines are helical). Polarization is inferred by application of the helical wave decomposition-values, indicating preferential involvement of this region of the protein surface in binding.;Enthalpies of adsorption derived from ITC are a strong function of surface coverage and differ widely for fresh and recycled Mono Q. They are positive and increase linearly with temperature, suggesting entropically-driven adsorption. Further, both van't Hoff and ITC derived enthalpies are relatively independent of the locus of mutation on the protein surface and therefore do not appear to play a pivotal role in the selectivity of ion-exchange adsorption. Data from DSC suggest lower thermal stability for the bound protein relative to the free species.;We study the effects of compressibility on reconnection using two antiparallel, sinusoidally perturbed vortex tubes. After showing the drawbacks of previously used initial pressure and density fields, we propose a new polytropic initial condition (PIC), which we argue to be the most appropriate choice for compressible DNS. Using PIC, vortex reconnection is then investigated in detail for an initial Reynolds number of 1000, with the pointwise maximum Mach number (M) ranging from 0.5 to 1.45. As M increases, reconnection is initiated earlier due to shocklet formation between the two vortex tubes. Once the shocklet dissipates, the reconnected vortices (bridges) suppress further reconnection, thereby increasing the reconnection timescale. At late times, compressibility effects reduce the twisting of vortex lines and hence core dynamics in the bridges. These results suggest that compressibility significantly alters CS interactions. |
