Bio-inspired study of thermal effects on NACA0012 airfoil at Reynolds Number of 33,000

The amount of solar and background radiation absorbed by birds vary according to their wing shape, pigmentation, porosity, etc. Birds are equipped with unique features to thrive, including attracting opposite sex, regulating body temperatures, and soaring in the sky. The research focuses on solar/sky radiation by examining how NACA0012 airfoil, representing the wing of a bird, performs when its upper surface temperature is higher or lower than the surrounding air. This is realised by performing 2-dimensional simulations in OpenFOAM at a Reynolds Number of 33,000, where Spalart-Allmaras model is used to simulate the flow turbulence. The upper surface of the airfoil is warmed to 330 K and cooled to 270 K at a pressure of 1 atm, an ambient temperature of 300 K, and a Mach number of 0.0725. The results illustrate the airfoil with the cooler top surface exhibits a lower drag and higher lift than its warmer top surface counterpart. A maximum reduction of drag coefficient from 0.065 to 0.061 and increase in lift coefficient from 0.89 to 0.93 at an angle of attack 11° are achieved. In short, tuning the upper surface of NACA0012 airfoil to temperatures lower than the ambient provides better aerodynamic performance

Rouse mode analysis of chain relaxation in polymer nanocomposites

Large-scale molecular dynamics simulations are used to study the internal relaxations of chains in nanoparticle (NP)/polymer composites

Rouse Mode Analysis of Chain Relaxation in Homopolymer Melts

We use molecular dynamics simulations of the Kremer–Grest (KG) bead–spring model of polymer chains of length between 10 and 500, and a closely related analogue that allows for chain crossing, to clearly delineate the effects of entanglements on the length-scale-dependent chain relaxation in polymer melts. We analyze the resulting trajectories using the Rouse modes of the chains and find that entanglements strongly affect these modes. The relaxation rates of the chains show two limiting effective monomeric frictions, with the local modes experiencing much lower effective friction than the longer modes. The monomeric relaxation rates of longer modes vary approximately inversely with chain length due to kinetic confinement effects. The time-dependent relaxation of Rouse modes has a stretched exponential character with a minimum of stretching exponent in the vicinity of the entanglement chain length. None of these trends are found in models that allow for chain crossing. These facts, in combination, argue for the confined motion of chains for time scales between the entanglement time and their ultimate free diffusion

Jainism and Buddhism in the life of the Tamil Subaltern People

A keen reading on the religious activities in Tamil speaking region down the centuries evidently exposes the two different predominant traditions existed with influence, namely ‘Vaithiga’ and ‘Avaithiga’ (Non-Vaithiga) religious traditions. These two indeed by their institutionalised reorganization largely influenced and initiated considerable changes in the socio-political and cultural life of Tamils. Apart form these institutionalised two, a few forms of the local deity worships were also in practice. However, this paper limits its focus on the institutionalised religions in general and Buddhism and Jainism in particular. It seems that the the Vaithiga religion, right from the beginning, has habitually extended its support and has also been supported by the Kings and Chieftains of power/authority whereas Buddhism and Jainism on the other hand have earned their support largely from the subaltern mass. This paper therefore argues that the success story of Buddhism and Jainism among the subaltern mass has not simply related to any external practices of the religions, but invariably structured within the very ‘humanistic’ ideology of the said religions themselves

A comparative approach to the Morality of Purananuru and Shi Jing

This article compares the data on 'Aram' found in two classics, Purananuru in Tamil and Shi Jing (诗经) in China. In both the collections, it is learnt that the messages of morality are the nucleus. By comparison, we can see how savants are considered to be prominent in society, how their unbiased ideas have been presented to the states of that time and how they have been developed into ethical values. Thus, it is possible to see from comparison that literature originating in two different lands has some similarities and some differences in ethical ideas

Rouse mode analysis of chain relaxation in polymer nanocomposites

Large-scale Molecular Dynamics simulations are used to study the internal relaxations of chains in nanoparticle (NP)/polymer composites. We examine the Rouse modes of the chains, a quantity that is closest in spirit to the self-intermediate scattering function, typically determined in an (incoherent) inelastic neutron scattering experiment. Our simulations show that for weakly interacting mixtures of NPs and polymers, the effective monomeric relaxation rates are faster than in a neat melt when the NPs are smaller than the entanglement mesh size. In this case, the NPs serve to reduce both the monomeric friction and the entanglements in the polymer melt, as in the case of a polymer-solvent system. However, for NPs larger than half the entanglement mesh size, effective monomer relaxation is essentially unaffected for low NP concentrations. Even in this case, we observe a strong reduction in chain entanglements for larger NP loadings. Thus, the role of NPs is to always reduce the number of entanglements, with this effect only becoming pronounced for small NPs or for high concentrations of large NPs. Our studies of the relaxation of single chains resonate with recent neutron spin echo (NSE) experiments, which deduce a similar entanglement dilution effect

Nanoparticle Motion in Entangled Melts of Linear and Nonconcatenated Ring Polymers

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Nanoparticle Motion in Entangled Melts of Linear and Nonconcatenated Ring Polymers

The motion of nanoparticles (NPs) in entangled melts of linear polymers and nonconcatenated ring polymers are compared by large-scale molecular dynamics simulations. The comparison provides a paradigm for the effects of polymer architecture on the dynamical coupling between NPs and polymers in nanocomposites. Strongly suppressed motion of NPs with diameter <i>d</i> larger than the entanglement spacing <i>a</i> is observed in a melt of linear polymers before the onset of Fickian NP diffusion. This strong suppression of NP motion occurs progressively as <i>d</i> exceeds <i>a</i> and is related to the hopping diffusion of NPs in the entanglement network. In contrast to the NP motion in linear polymers, the motion of NPs with <i>d</i> > <i>a</i> in ring polymers is not as strongly suppressed prior to Fickian diffusion. The diffusion coefficient <i>D</i> decreases with increasing <i>d</i> much slower in entangled rings than in entangled linear chains. NP motion in entangled nonconcatenated ring polymers is understood through a scaling analysis of the coupling between NP motion and the self-similar entangled dynamics of ring polymers