Direct numerical or large-eddy simulations of the majority of spatially inhomogeneous turbulent flows require turbulent inflow boundary conditions. A potential implication is that any results computed may be strongly influenced by the prescribed instantaneous inlet velocity profiles. Such profiles are practically never available, and a usual practice is to generate synthetic inflow data satisfying certain statistical properties, which may, for example, be known from experimental data or empirical correlations. The present paper describes a new method for generating turbulent inflow data based on digital filters that is capable of reproducing specified statistical data. Two variants of the approach are presented: a simple method in which the Reynolds stresses and a single length scale are prescribed, and a more detailed approach that is able to reproduce the complete Reynolds-stress tensor as well as any given, locally defined, spatial and temporal correlation functions. The application of the methods to a plane jet flow and to a developing wall boundary layer serve to demonstrate the applicability of the approach.

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The rheology of submicron thick polymer melt is examined under high normal pressure conditions by a recently developed photobleached‐fluorescence imaging velocimetry technique. In particular, the validity and limitation of Reynold equation solution, which suggests a linear through‐thickness velocity profile, is investigated. Polybutene (PB) is sheared between two surfaces in a point contact. The results presented in this work suggest the existence of a critical pressure below which the through‐thickness velocity profile is close to linear. At higher pressures however, the profile assumes a sigmoidal shape resembling partial plug flow. The departure of the sigmoidal profile from the linear profile increases with pressure, which is indicative of a second‐order phase/glass transition. The nature of the transition is confirmed independently by examining the pressure‐dependent dynamics of PB squeeze films. The critical pressure for flow profile transition varies with molecular weight, which is consistent with the pressure‐induced glass transition of polymer melt. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 708–715

8Fouling by asphaltene, which constitutes the densest, most polar fraction of crude oil, poses a serious 9 problem for the oil production industry. In order to obtain a fundamental understanding of asphaltene 10 deposition it is necessary to determine both the thermodynamics and kinetics that govern this process. In 11 recent years, there have been numerous studies of the kinetics of asphaltene adsorption, however, a 12 consensus on the model that best describes asphaltene adsorption remains elusive. In this paper the 13 adsorption of asphaltene from solution in toluene onto a gold surface is investigated using a quartz crystal 14 microbalance inside a flow cell. The kinetics of adsorption depends on the state of asphaltene in solution 15 and the adsorption behaviour alters with long-time aging of asphaltene solutions. A model is developed 16 that links the kinetics of asphaltene adsorption to the bulk solution properties in terms of coexisting 17 monomer and multimer states. A large portion of deposited asphaltene is effectively irreversibly bound 18 and not easily removed by rinsing with toluene. The model suggests that asphaltene-asphaltene 19interactions play an important role in the formation of irreversibly bound deposits, which could lead to 20 fouling problems. 21 22

Two-dimensional (2D) strip-theory modelling of unsteady gust-aerofoil interaction is standard practice in many industrial applications, but the limits of applicability of 2D unsteady flow modelling on 3D wing and rotor geometries are not well understood. This paper investigates the effects of 3D geometry features, such as finite span, taper, sweep and rotation, on the unsteady lift response to gusts, and the flow-physical differences between 2D and 3D geometries in unsteady flow. A frequency-domain inviscid vortex lattice model is validated and used for the 3D analysis. The results are compared to unsteady transfer functions from 2D linear analytic theory (e.g. Theodorsen and Sears functions). The study agrees with previous research findings that 3D effects are most significant at low reduced frequencies and low aspect ratios, as well as near the wing tips. The driving cause of 3D response is shown to be the wake vorticity: both streamwise and spanwise components of unsteady wake vorticity must be modelled. The study concludes by investigating whether unsteady response of more complex 3D wing and rotor geometries can be represented by the response of a rectangular wing. The results indicate that this is possible for tapered wings and rotating blades, but not for swept wings. Nomenclature Influence matrix Semi-chord (m) c Chord (m) Cl Local lift coefficient CL Total lift coefficient Force (N) Reduced frequency Lift (N) Number of chordwise lattice panels Surface normal vector Number of blades Radius