Design optimization of natural laminar flow bodies in compressible flow

An optimization method has been developed to design axisymmetric body shapes such as fuselages, nacelles, and external fuel tanks with increased transition Reynolds numbers in subsonic compressible flow. The new design method involves a constraint minimization procedure coupled with analysis of the inviscid and viscous flow regions and linear stability analysis of the compressible boundary-layer. In order to reduce the computer time, Granville's transition criterion is used to predict boundary-layer transition and to calculate the gradients of the objective function, and linear stability theory coupled with the e(exp n)-method is used to calculate the objective function at the end of each design iteration. Use of a method to design an axisymmetric body with extensive natural laminar flow is illustrated through the design of a tiptank of a business jet. For the original tiptank, boundary layer transition is predicted to occur at a transition Reynolds number of 6.04 x 10(exp 6). For the designed body shape, a transition Reynolds number of 7.22 x 10(exp 6) is predicted using compressible linear stability theory coupled with the e(exp n)-method

Effects of forebody geometry on subsonic boundary-layer stability

As part of an effort to develop computational techniques for design of natural laminar flow fuselages, a computational study was made of the effect of forebody geometry on laminar boundary layer stability on axisymmetric body shapes. The effects of nose radius on the stability of the incompressible laminar boundary layer was computationally investigated using linear stability theory for body length Reynolds numbers representative of small and medium-sized airplanes. The steepness of the pressure gradient and the value of the minimum pressure (both functions of fineness ratio) govern the stability of laminar flow possible on an axisymmetric body at a given Reynolds number. It was found that to keep the laminar boundary layer stable for extended lengths, it is important to have a small nose radius. However, nose shapes with extremely small nose radii produce large pressure peaks at off-design angles of attack and can produce vortices which would adversely affect transition

Biomedical applications of polypeptide multilayer nanofilms and microcapsules

The past few years have witnessed considerable growth in synthetic polymer chemistry and physics, biomaterials science, and nano-scale engineering. Research on polypeptide multilayer films, coatings, and microcapsules is located at the intersection of these areas and are promising materials for applications in medicine, biotechnology, environmental science. Most envisioned applications of polypeptide multilayers have a biomedical bent. This dissertation on polypeptide multilayer film applications covers key points of polypeptides as materials, means of polymer production, film preparation, film characterization methods, and key points of current research in basic science. Both commercial and designed peptides have been used to fabricate films for in-vitro applications such as antimicrobial coatings and cell culture coatings and also microcapsules for drug delivery applications. Other areas of product development include artificial red blood cells, anisotropic coatings, enantioselective membranes, and artificial viruses

Cosmological constraints from applying SHAM to rescaled cosmological simulations

We place constraints on the matter density of the Universe and the amplitude of clustering using measurements of the galaxy two-point correlation function from the Sloan Digital Sky Survey (SDSS). We generate model predictions for different cosmologies by populating rescaled N-body simulations with galaxies using the subhalo abundance matching (SHAM) technique. We find ΩM = 0.29 ± 0.03 and σ8 = 0.86 ± 0.04 at 68 per cent confidence by fitting the observed two-point galaxy correlation function of galaxies brighter than Mr = -18 in a volume-limited sample of galaxies obtained by the SDSS. We discuss and quantify potential sources of systematic error and conclude that while there is scope for improving its robustness, the technique presented in this paper provides a powerful low-redshift constraint on the cosmological parameters that is complementary to other commonly used methods

Active nematics on a substrate: giant number fluctuations and long-time tails

We construct the equations of motion for the coupled dynamics of order parameter and concentration for the nematic phase of driven particles on a solid surface, and show that they imply (i) giant number fluctuations, with a standard deviation proportional to the mean and (ii) long-time tails $\sim t^{-d/2}$ in the autocorrelation of the particle velocities in $d$ dimensions despite the absence of a hydrodynamic velocity field. Our predictions can be tested in experiments on aggregates of amoeboid cells as well as on layers of agitated granular matter.Comment: Submitted to Europhys Lett 26 Aug 200

Cloud Based Framework for Autism Spectrum Disorder Therapy App

In the current era of connected devices like smart phones, the demand for data storage is increasing drastically for some set of applications involving multiuser. We require a centralized storage system where data can be accessed from any part of the world using various devices like mobiles and tabs. The cloud provides services for storing data on remote servers which can be accessed through the Internet. It is maintained, operated and managed by a cloud storage service provider on storage servers that are built on virtualization techniques and has large computational power compared to the mobile devices. The paper presented here proposes a cloud based framework for the application “AshaDeep” which was developed to provide technological support for autistic children. This mobile application generates huge number of images and data in a multiuser environment as a part of learning and evaluation activity. In this app we aim to unite multiple users by developing a common platform to track the progress of the autism children and combat autism

A Lattice-Boltzmann model for suspensions of self-propelling colloidal particles

We present a Lattice-Boltzmann method for simulating self-propelling (active) colloidal particles in two-dimensions. Active particles with symmetric and asymmetric force distribution on its surface are considered. The velocity field generated by a single active particle, changing its orientation randomly, and the different time scales involved are characterized in detail. The steady state speed distribution in the fluid, resulting from the activity, is shown to deviate considerably from the equilibrium distribution.Comment: 8 pages, 13 figure

A Dynamic Renormalization Group Study of Active Nematics

We carry out a systematic construction of the coarse-grained dynamical equation of motion for the orientational order parameter for a two-dimensional active nematic, that is a nonequilibrium steady state with uniaxial, apolar orientational order. Using the dynamical renormalization group, we show that the leading nonlinearities in this equation are marginally \textit{irrelevant}. We discover a special limit of parameters in which the equation of motion for the angle field of bears a close relation to the 2d stochastic Burgers equation. We find nevertheless that, unlike for the Burgers problem, the nonlinearity is marginally irrelevant even in this special limit, as a result of of a hidden fluctuation-dissipation relation. 2d active nematics therefore have quasi-long-range order, just like their equilibrium counterpartsComment: 31 pages 6 figure

Classical XY model with conserved angular momentum is an archetypal non-Newtonian fluid

We find that the classical one-dimensional (1D) XY model, with angular-momentum-conserving Langevin dynamics, mimics the non-Newtonian flow regimes characteristic of soft matter when subjected to counter-rotating boundaries. An elaborate steady-state phase diagram has continuous and first-order transitions between states of uniform flow, shear-banding, solid-fluid coexistence and slip-planes. Results of numerically studies and a concise mean-field constitutive relation, offer a paradigm for diverse non-equilibrium complex fluids

Rheology of Active-Particle Suspensions

We study the interplay of activity, order and flow through a set of coarse-grained equations governing the hydrodynamic velocity, concentration and stress fields in a suspension of active, energy-dissipating particles. We make several predictions for the rheology of such systems, which can be tested on bacterial suspensions, cell extracts with motors and filaments, or artificial machines in a fluid. The phenomena of cytoplasmic streaming, elastotaxis and active mechanosensing find natural explanations within our model.Comment: 3 eps figures, submitted to Phys Rev Let